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<h1><img src="../images/edu.gif" align="left" width="100" height="83" border="2" vspace="5" hspace="9">Amateur Radio Continuing Education<img src="../images/w4rnlwwr.gif" align="right" width="99" height="83" border="2" vspace="5" hspace="9"></h1>
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<h3>L. B. Cebik, W4RNL</h3>
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<p>Some 35 years of teaching have given me an abiding interest in the continuing education of radio amateurs. As an Educational Advisor to the ARRL, I have prepared since 1992 an article for each of the annual <i>Proceedings of the National Education Workshop</i>. Because these volumes do not see a wide circulation, and because the articles I have contributed might have a useful note or two within them, I am placing them here. Readers should make an attempt to look through the entire contents of the series for other very useful and insightful articles, full of tips and techniques to make ham teaching--both before and after licensing--more effective.</p>
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<p>A number of the articles contain references to web sites, periodicals, vendors, clubs, and other sources having addresses. Such information grows stale and outdated fairly quickly. However, ARRL and <i>QST</i> are 2 enduring sources for updated information. Web search engines are another good source of what is current.</p>
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<p>The published items are linked from the bibliographical list below.</p>
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<p><a href="edu10.html">"A Short Tale About the Family, the Fox, and the Moxon"</a> <i>Proceedings of the 2002 National ARRL Education Workshop</i>, (Newington: ARRL, 2002), pp. 95-99</p>
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<p><a href="edu8.html">"Youth Teachers and Tutors; or Elmer Does Not Have to Be an Adult"</a> <i>Proceedings of the 1999 National ARRL Education Workshop</i>, (Newington: ARRL, 1999), pp. 81-84</p>
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<p><a href="edu9.html">"The Internet as a Teaching Tool: Using It Well"</a> <i>Proceedings of the 1999 National ARRL Education Workshop</i>, (Newington: ARRL, 1999), pp. 76-80</p>
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<p><a href="edu7.html">"QRP: A Newcomer's and Old-Timer's Challenge"</a> <i>Proceedings of the 1998 National ARRL Education Workshop</i>, (Newington: ARRL, 1998), pp. 30-38</p>
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<p><a href="edu6.html">"Introducing the "All-Band" Doublet: What the Student and the Instructor Should Keep in Mind"</a> <i>Proceedings of the 1998 National ARRL Education Workshop</i>, (Newington: ARRL, 1998), pp. 39-46</p>
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<p><a href="edu5.html">"Antenna Modeling Programs as Teaching Tools,"</a> <i>Proceedings of the 1996 National ARRL Education Workshop</i>, (Newington: ARRL, 1996), pp. 28-35</p>
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<p><a href="edu4.html">"Why 0.707? Teaching R.M.S. Values of AC Voltage and Current,"</a> <i>Proceedings of the 1995 National ARRL Education Workshop</i>, (Newington: ARRL, 1995), pp. 33-40</p>
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<p><a href="edu3.html">"Beyond the License: Teaching the Principles of Effective Station Design,"</a> <i>Proceedings of the 1994 National ARRL Education Workshop</i>, (Newington: ARRL, 1994), 15-22</p>
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<p><a href="edu2.html">"The Blackboard Jumble,"</a> <i>Proceedings of the 1993 National ARRL Education Workshop</i>, (Newington: ARRL, 1993), 27-34</p>
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<p><a href="edu1.html">"Continuing Ham Education,"</a> <i>Proceedings of the 1992 National ARRL Education Workshop</i>, (Newington: ARRL, 1992), pp. 34-41</p>
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<p><i>Updated 09-06-2004. © L. B. Cebik, W4RNL. Data may be used for personal purposes, but may not be reproduced for publication in print or any other medium without permission of the author.</i></p>
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<p>The availability of on-line information varies with time, with some sites appearing and others disappearing. One of the more durable and useful sites is the following one from Australia;</p>
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<p><a href="https://web.archive.org/web/20120615151516/http://radioelectronicschool.net/" target="_blank"><b>Radio Electronics School</b></a> (web.archive.org): a many-section course on the fundamentals of electronics for new amateur radio operators.</p>
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<p><a href="../radio.html"><img src="../images/rtnhome.gif" align="bottom" width="40" height="40"> Return to Amateur Radio Page</a></p>
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<p class="topics-footer">Topics: <a href='../topics.html#education'>Education</a></p><br>
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<h1><img src="../images/edu.gif" align="left" width="100" height="83" border="2" vspace="5" hspace="9"> Continuing Ham Education <img src="../images/w4rnlwwr.gif" align="right" width="99" height="83" border="2" vspace="5" hspace="9"></h1>
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Since the advent of the VEC program, there has been a dramatic reduction in the availability of quality technical self-instructional materials for radio amateurs. Part of the decline owes to the concentration of instruction upon the licensing process, which involves only rudimentary technical information presented in fragments. Although this presentation parallels the structure of the license examinations, it fails to give students any sense of the fact that communications electronics consists of a coherent and interrelated set of ideas, formulas, and techniques. Another part of the decline in available self- instructional material derives from concerns about the growing median age of licensed hams. Consequently, great and appropriate effort has gone into recruiting potential hams from among the nation's youth. The program, whose success is becoming apparent in license statistics, has taken energy from the next step in amateur education: post-licensing education in the basics of communications electronics.
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<h3>THE CLIENTELE</h3>The consequences of the lack of suitable instructional materials are many. Recently licensed amateurs have difficulty understanding the technical articles in QST and other amateur radio journals. Many of these amateurs feel that the space is wasted and clamor for more general interest articles. At one time, hams raised an equal clamor for more technical articles and more thorough technical articles. With few resources to ease the way into understanding the technical fundamentals of amateur radio, quality assurance of amateur signals rests more with the manufacturer's ability to make foolproof equipment and less with the individual amateur's ability to correct technical difficulties. Accompanying the reduced ability comes a potentially reduced appreciation of the importance of bringing signals into line with regulatory specifications. None of these situations, however, should be interpreted as meaning that hams, in general, do not want to know.
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<p>Despite the absence of suitable materials for amateur instruction beyond the requirements of licensing, significant numbers of hams do wish to learn the technical aspects of their avocation. Informal questioning of amateurs in my local region has produced some interesting facts about the desire to learn. At least 1 percent and perhaps as many as 5 percent of the hams in the area at any one time wish they could participate in some form of electronics education related to their interests in amateur radio. If one were to extrapolate from these figures that in any one year 1 percent of U.S. hams would participate in self-instruction or local classes, sales of instructional texts would number almost 5,000 per year, enough to ensure a suitable return on the investment in publishing such materials. If consciousness-raising and recruitment of interest are added to these unsolicited expressions, then sales and activity would be considerably higher.</p>
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<p>The potential clientele for amateur instruction shows little demographic differentiation. Hams of all ages, from teens to retirees, equally express interest in further ham education. In real classes that extend for several weeks, the drop-out rate is highest among those in their 30s, who have a combination of jobs and children to divert them from their interest. Otherwise, attendees remain loyal to the class if instruction is good and if interest in the student as an individual is a key ingredient in the teaching. Classes for amateur licensees show little, if any, signs of socio-economic differentiation beyond that encountered among the amateur population as a whole. The understanding of a mystery--a very appealing mystery of how something magical works--has much of the appeal that it had in the early days of radio. It is an appeal without the boundaries that separate many other activities in society. I personally have taught college professors and plumbers in the same class, and they had much the same attitude and interest.</p>
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<p>If these informally gathered data hold true over the amateur population as a whole, then the success in fulfilling the need for post-licensing amateur radio education will depend upon the quality of the materials and assistance we provide.</p>
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<h3>THE NEEDS</h3>Individual and informal group instruction in radio fundamentals requires one or more texts written expressly for this purpose. Modern circumstances both of communications technology and of activities permitted under amateur service licenses strongly suggest that the older practice of combining all radio fundamentals in a single text is no longer practical or effective. In addition, the goals of self-study or small group informal education suggest that a single volume might be self-defeating, overwhelming the ham who wishes to increase his or her know-how. Therefore a series of texts, each covering a significant segment of the fundamentals of communications technology, appears best to describe the need.
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<p>Existing self-instructional materials do not meet the needs of amateur radio licensees. Current licensing manuals consist largely of questions and answers from the examination pool. In almost all such manuals, excluding the A.R.R.L. study guides, the only text is a brief explanation of the correct answer to a given question. Only League guides provide connected text to introduce ideas in a reasonably coherent manner, but the scope of these guides precludes the development of crucial basic ideas in radio communications. For example, the General Class guides have yet to introduce the concept of Q and its importance to many facets of radio work. Resonance, too, is missing. Wave conditions on feedlines is nowhere seen. Little wonder new licensees have many misconceptions of how things actually work if all they have read is a license guide. This is no criticism of such guides. They were never intended as substitutes for appropriate instructional materials.</p>
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<p>Perhaps the two best basic texts for hams were Bob Shrader's <i>Amateur Radio: Theory and Practice</i> and George Grammer's <i>A Course in Radio Fundamentals</i>. Both are unavailable, and neither may be truly apt to the contemporary need. Shrader's book was keyed to older FCC study questions and was only as comprehensive as that question pool. As a one-volume coverage of amateur electronics, it could not address crucial points as leisurely as might be desirable. Yet, its thickness gives it a formidable appearance. Grammer's book is an A.R.R.L. classic and is still a model of lucidity and important detail. However, its World War II origins show, as the world of amateur radio electronics has widened almost beyond belief. The development of amateur radio instructional materials requires rethinking to capture the best of these books while meeting today's new circumstances.</p>
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<p>Self-instructional materials in electronics abound. NRI and CIE have offered home instruction courses for as long as most hams can remember reading electronics magazines. Heath transformed its excellence in writing kit-building manuals into equally excellent self-instructional materials. However, commercial materials aim at a general electronics education sufficient to prepare the student for work as a technician across a broad spectrum of the overall field. Topics of special interest to hams occur only as advanced or specialized instruction, or they do not appear at all. Although these self-instruction courses are excellent at what they do, they do not immediately meet the needs of amateur radio licensees.</p>
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<p>Even if there were suitable self-instructional texts, continuing ham education would have other needs as well. If the texts are to serve small group informal instruction as well as self-study, volunteer instructors would greatly benefit from instructor guides. Volunteer instructors very often have insufficient background or time to develop lesson plans, to create classroom-size visual reinforcement materials, or to design effective classroom demonstration experiments. The cause of good instruction creates a need for guides to assist instructors in their efforts.</p>
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<p>The development of materials requires oversight and coordination. The use of those materials in group situations also calls for assistance and coordination. The fulfillment of these needs creates its own need for an effective organization of volunteers and others to ensure the successful production of materials and the establishment of classes for hams.</p>
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<h3>THE PLACE OF THE LEAGUE IN CONTINUING HAM EDUCATION</h3>Fulfilling the needs of post-licensing amateur radio self-instruction and informal classes will require two coordinated developmental efforts: 1. creation of written instructional materials and supplements, and 2. organization of the people who are committed to and involved in various aspects of the instructional program. No organization inside or outside amateur radio is qualified to take on such a task except A.R.R.L. With access to writing and teaching talents, with access to clubs and other potential sponsoring groups, with experience in recruiting, teaching, and licensing new hams, with publication experience and facilities, with a staff experienced in dealing with amateur radio licensees, and with a membership that includes the single largest collection of U.S. hams, the League is positioned as no other commercial or nonprofit organization to undertake such an effort.
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<p>The activities required to develop a continuing ham education program represent a major addition to the current primary challenge given to the A.R.R.L. Educational Activities Department. It is possible to implement such a program in stages, reevaluating each stage before beginning the next. 1. The first stage, which is key to the entire program, is the development of texts. This stage requires oversight, recruitment of writers, determination of the basis of writer efforts--pay, volunteer, other--and coordination of publishing efforts. 2. The second stage would be the development and publication of instructional guides for use with the texts in classes. This stage might be undertaken solely as a service to affiliated clubs and potential instructors, even if the League determines to limit its activity in this field. 3. The third stage--which includes active recruitment of Educational Advisors to serve this effort, continuing assistance to sponsoring groups, and other activities associated with a continuing education enterprise--requires the greatest commitment of long-term League energy. Division of the project into stages represents one way in which the League may cautiously enter into such a program of post-licensing technical education.</p>
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<h3>BOOKS</h3>Without adequate written materials, no educational program can succeed. The fundamental materials necessary for post-licensing amateur education are a series of texts which segment basic communications electronics into logical teaching units. The specific units chosen should reflect practical as well as theoretical considerations. For example, in the following proposed scheme, the subject of digital information techniques precedes basic VHF and UHF techniques. The reason for this progression stems from the tendency of newer Technician class amateurs to enter into packet and other digital modes early on. They use commercial equipment for RF generation and reception, while developing interfaces or interconnections with their computers and packet modems. Thus, understanding packet and its requirements is a more immediate need than understanding the nonadjustable transceiver that sends and receives packet. Similar considerations apply to the exact placement of every volume in the series.
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<p>There are numerous subdivisions one might use to teach electronics, but the following scheme has several advantages. First, each text presents a coherent topic which permits the student to increase his or her knowledge in a systematic way. Each avoids the temptation to collect a hodge-podge of information that lacks the proper connective threads. Second, the series of texts as a whole shows a similar developmental pattern. Third, the topics parallel in numerous ways the material in the <i>A.R.R.L. Handbook</i>, which allows students to read more deeply into a subject. Should an alternative scheme be chosen for a collection of texts, it should be educationally defensible in similar terms.</p>
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<p>1. <b>Basic DC, AC, and RF Circuit Concepts</b>: This is the basic volume of the series and covers fundamental circuit concepts and the action of most major passive components. It would introduce Ohm's Law and related topics, AC and RF phenomena, reactance and Q, resonance, filters, transformers and coupling, and impedance matching.</p>
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<p>2. <b>Analog Circuit Concepts and Amplifier Devices</b>: The second volume would introduce the concepts of amplification and oscillation, along with the basic amplifying components: the transistor, the FET, and the vacuum tube. It would thoroughly cover low and high power amplifying circuitry and biasing amplifiers for each class of operation, along with adjunct topics such as positive and negative feedback, spurious oscillation, frequency limitations, amplifier types, and the op amp.</p>
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<p>3. <b>Digital Devices and Techniques</b>: Volume three introduces the reader to digital integrated circuit functions and to the dominant lines of digital ICs. Beginning with gate functions, the volume would not only provide insight into the available functions and combination of functions, but would demonstrate practical circuits for ham applications. It would also cover specialized digital ICs found in amateur use and explain basic computer and memory chips.</p>
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<p>4. <b>Basic Antenna and Feedline Concepts</b>: If one considers the A.R.R.L. Antenna Book a reference manual and Maxwell's Reflections a special purpose advanced text, then a truly basic introduction to the fundamental concepts of antennas and feedlines does not exist. Such a volume would introduce antenna energy conversion independently of antenna type, later relating the properties of practical antennas to basic concepts. The text would also introduce transmission line concepts independently of past misconceptions. These fundamentals would expand to include specialized antennas, such as ground-mounted verticals (and arrays), beams (both parasitic and driven), and others; impedance transformation; and transmitter-to-line impedance matching.</p>
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<p>5. <b>Digital Information Techniques</b>: This volume introduces digital information techniques ranging from CW to RTTY, AMTOR, and Packet, along with information on specialized telemetry and other modes of encoding RF signals with decodable data. Included would be information on the principles of encoding and practical techniques for accomplishing the goal, with supplemental details to prepare the amateur to participate intelligently and successfully in each mode of operation.</p>
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<p>6. <b>Voice and Picture Modulation</b>: Analog information encoding upon RF signals is a companion to the preceding volume and would explain the dominant methods of modulating and demodulating RF with decodable voice and picture information. Double side-band AM, SSB, and FM would dominate the volume, although the volume should permit the reader to appreciate the entire spectrum of modulation types included in FCC regulations, along with practical circuits and techniques for implementing them.</p>
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<p>7. <b>Basic Transmitter and Receiver Design</b>: With the conceptual building blocks established so far, the reader is prepared to understand the basic concepts used in the design of modern transmitters and receivers (or transceivers). Historical designs (such as regenerative receivers and frequency-multiplying transmitters) could well illustrate both design objectives and limitations. However, the circuits and overall functional flow of modern units would be stressed to encourage understanding of equipment typically used by amateurs.</p>
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<p>8. <b>Basic VHF, UHF, and Microwave Techniques</b>: This volume would introduce hams to the special considerations common to VHF, UHF, and relevant microwave equipment, circuits, and devices encountered by radio amateurs. The coverage would include receivers and converters, transmitters and transverters, and antennas and feedlines, with appropriate mention of safety precautions applicable to frequencies above HF.</p>
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<p>9. <b>Basic Test Equipment and Techniques</b>: Completing the series would be an introduction to the basic concepts, circuits, and instruments used to measure electronic phenomena. The text would emphasize instruments reasonably available to amateurs and techniques amateurs might use to measure relevant but special parameters, such as reactance and impedance.</p>
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<p>The overall format of the proposed texts might well be the current A.R.R.L. standard: 8.5 by 11 inches in size with two columns of text and variable size graphics to sustain interest in the page. Each volume would run 100 to 150 pages, divided into several chapters. Wherever possible, photographs should complement graphics and circuit diagrams to familiarize the reader with the appearance of components, circuits, and instruments. Each text chapter would include the following: 1. presentation and illustration of basic concepts and relationships, 2. extended explanations of critical ideas, 3. notes on the relationship of the current concepts to others in electronics, 4. sample practical applications with actual and usable circuits, 5. experiments the reader can perform, where applicable, and 6. references to other books for further information on the subject.</p>
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<p>Mathematics is inevitable in any electronics text: in these texts, formulas may run to reasonable complexity so long as explanations of the terms and relationships are given. However, for mathematics beyond high school second-year algebra (for example, polar notation, complex trigonometry, and statistical notations), an appendix or a side bar in the chapter should explain the rudiments of notation and procedure to orient the reader. Calculus should not be necessary.</p>
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<h3>ADJUNCT INSTRUCTIONAL MATERIALS</h3>As an adjunct to the texts, it might well be possible to design or adapt computer programs in BASIC to perform calculations demonstrated in each text. There are many public domain programs covering basic electronic formulas up through calculations of amplifier parameters and transmission line functions. There are two ways of presenting these programs: 1. as a collection of independent programs, and 2. as a coherent program under a single master menu per text. Without much difficulty, a programmer of moderate experience could write a master menu program to link the program collections in each text. The result would be a reasonably comprehensive computer program for basic amateur radio mathematics.
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<p>The use of the proposed texts in informal classes taught by volunteers sponsored by local radio clubs or similar groups requires little more of the student than attentive reading and listening, abetted by hands-on experience. However, much is required of the average volunteer instructor who often has little teaching background. Therefore, instructors need guidance in the use of the texts in classes, which calls for a series of instructor guides. The current A.R.R.L. guides for Novice/Technician classes and for General classes are two variations on the guidance theme. The guides should be keyed to individual texts in the series and contain lesson plans for each unit of material. Each plan should include a teaching time estimate, a set of objectives, requirements for teacher preparation, a list of required materials, and a list of classroom demonstrations and experiments. The last element, the demonstrations, should be outlined in detail, with hints on how to make them effective in a classroom. In addition to these detailed lesson plans, the instructor guides should also have a master plan for the entire volume and other information to assist prospective instructors to estimate and plan for the duration of the class term. Each guide should also contain graphics that the instructor can use in the classroom, either by photocopying pages from the guide or by transferring the graphic to an overhead projector transparency.</p>
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<p>In addition to the specific guidance needed to teach each text, instructors should have access to more general assistance in teaching classes of this type. Such material may be appended to each volume, or a master instructor's manual might be produced. Such a manual would be similar in relevant content to the current <i>League Instructor's Manual</i>, with adjustments made for the differences between conducting licensing classes and teaching continuing education classes. Among the new material might be how to retain student interest and loyalty in a longer term class, how to master mathematical operations, how to use hands-on experiments in class to reinforce the relationship of theory and practice, how to learn the needs of individual students to make teaching more effective, and a number of other topics.</p>
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<h3>OVERSIGHT, ASSISTANCE, AND RECRUITMENT</h3>However modest or extensive, a ham continuing education program requires human effort. Some person-hours will be volunteer; others will be paid staff; still others will be by contract or other temporary paid vehicle. The organization of the program to ensure the most efficient and effective use of all personal exertions also has ramifications for program costs. Even if the initial stages of the program are small, they require the definitive assignment of an A.R.R.L. staff member. The most logical placement of the program is within the Educational Activities Department. The need for a full- or part-time assignment to the program will vary with the workload as the commitment and the program develop.
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<p>For the text phase of the program, the staff member would coordinate writing and publishing efforts to ensure a set of worthy League publications. The staff member would work directly with authors or with a series editor. Similar considerations apply to the writing of instructor guides, although the sources of materials may be more diverse and require extensive contact with instructors and possibly with Educational Advisors in the field. If the program extends (either sooner or later) to extensive field efforts with club or group sponsorship of classes and volunteer instructors, then staff coordination responsibilities will grow almost exponentially. Part of that task will include extensive informational assistance to ensure that groups and instructors have the best and most complete set of materials possible. Another part of the task may well be the recruitment of club sponsors and volunteer instructors to initiate and enlarge educational programs at a local level. Although precise activities may differ from those presently undertaken by the Educational Activities Department to recruit youthful new hams, they will be no less extensive or demanding.</p>
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<p>Any program as extensive as a continuing ham education program requires general oversight. First, the program must meet the terms of League policy as determined by its Board of Directors. Second, the program must be expert, meeting the highest standards of publication and continuing education. Third, the program must be responsive to real needs expressed by individuals and groups of hams throughout the country. Fourth, the actions and products of the program and its personnel must come under periodic review.</p>
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<p>Perhaps the best means of meeting these needs would be a volunteer program planning and oversight committee composed of several different types of members. 1. The committee should include one or more Directors to ensure that all detailed plans meet the terms set by Board policy. Director members would also ensure knowledgeable and regular reporting to the Board on the progress of the program. 2. The staff member(s) assigned to the program should participate fully in the committee's work. Most feedback and problems will likely come first to the attention of a staff member. Too, staff members are most likely to be thoroughly conversant with practical and temporary problems, such as publication delays. 3. Volunteer experts in education and in writing technical materials who are also radio amateurs should be members of the committee. Whether in planning, review, or evaluation, these members can best assure that the elements of the program meet the highest standards of technical continuing education. Indeed, part of their task may be to establish these standards.</p>
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<p>The extensive series of texts suggested for the continuing ham education program presents a major writing challenge. To ensure the highest quality writing, each volume should be prepared by a writer of known quality. Coordination of production would be handled by the League staff member assigned responsibility for the program. However, the staff member should not be expected to be responsible also for the accuracy of the technical content and the consistency and quality of the writing style of each volume in the series. Rather, the program requires a series editor for this duty. Consistency of graphics (both type and quantity), terminology, chapter and paragraph size and style, index considerations, allowable volume-to-volume repetition of material, amount and type of mathematical material, and numerous other tasks that contribute to making the series a cohesive whole strongly suggest the need for a series editor whose work would be no less than that of the individual volume authors.</p>
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<p>The associated instructor guides may be a function assigned either to a staff member or to one or more experts in such matters. The requirements for lesson plans built around the texts and the requirements for usable classroom graphics may suggest a collaborative effort. A master teaching guide that would include recruiting and teaching aids may be otherwise assigned. The final products, however, require oversight and editing by a single hand to ensure consistency of style, level, and format.</p>
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<p>A relatively small number of volunteer Educational Advisors (EAs) currently serve the efforts of the Educational Activities Department. Most of these dedicated teachers and teaching experts are concerned with the recruitment and training of youth for entry into the ranks of radio amateurs. If a program of continuing ham education comes into existence and includes assistance for clubs and other groups which sponsor classes, then further recruitment of specialized EAs seems in order. Continuing education of people of all ages and levels of background presents problems somewhat different from those facing teachers of licensing classes. The term of student commitment is longer. The technical level of the material is higher. The balance of understanding and mastering the mathematics of various principles differs from that associated with basic licensing. The required sophistication of classroom demonstrations is much greater. These and other differences strongly suggest the recruitment of specialized EAs with expertise and interest in post-licensing continuing education to supplement the current array of EAs. These volunteers could go a long way toward easing the burden of the program on the League staff member assigned to shepherd it.</p>
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<p>Recruiting clubs and other groups to sponsor continuing education classes for hams requires a continuing effort. In the area of recruiting and teaching potential hams, the Educational Activities Department is already familiar with the formidable task of acting as a liaison with these groups and providing them with timely and effective services. Similar, but largely distinct, activities would be required to assist groups who may take an interest in teaching classes over the material in any of the texts in the proposed series. Servicing instructors and sponsoring groups and making them part of the League family would require a significant commitment of staff time and energy. Nonetheless, providing such services would be as crucial a step to program success as it is in the present programs of the Educational Activities Department.</p>
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<h3>BENEFITS OF A POST-LICENSING CONTINUING HAM EDUCATION PROGRAM</h3>The primary benefit of a program of continuing ham education would be, overall, an amateur community whose technical knowledge more closely approximates regulatory expectations. Although amateur radio will always hold an important place for the individual whose principal, if not sole, interest is communications, encouraging and making possible further technical expertise is an equally important aspect of the traditions and the potentials of the service. The joy of understanding may be sufficient reward for some hams. For others, the ability to engage in building or servicing equipment may be the result. Some younger hams may proceed from amateur continuing education efforts into careers in electronics. Hams of many ages may begin to participate in the more experimental aspects of amateur radio, whether these involve digital signal processing, new modulation methods, greater computer-radio interface capabilities, VHF-UHF-microwave experimentation, or satellite activity. The baseline measure of success, however, is simply a closer adherence to and appreciation of the technical requirements of amateur transmitted signals.
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<p>The proposed program of continuing ham education does not compete with any existing educational program. Rather, in a manner consistent with the traditions of amateur radio, the program might help to increase the number of people entering technical electronics careers. In the end, however, such a program--while not applicable to every ham--would raise the general level of technical know-how among individuals and groups throughout amateur radio. That accomplishment would suffice to justify the energy and resources required by the program of continuing ham education. With the VEC program and its associated recruitment and educational activities well-established, the time may be ripe to give full deliberation to this next important step in educational services to the amateur community.</p>
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<p><i>From</i> Proceedings of the 1992 National ARRL Education Workshop<i>, (Newington: ARRL, 1992), pp. 34-41 © L. B. Cebik, W4RNL. Data may be used for personal purposes, but may not be reproduced for publication in print or any other medium without permission of the author.</i><br>
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<title>A Short Tale About the Family, the Fox, and the Moxon</title>
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<h1><img src="../images/edu.gif" align="left" width="100" height="83" border="2" vspace="5" hspace="9"><img src="../images/w4rnlwwr.gif" align="right" width="99" height="83" border="2" vspace="5" hspace="9">A Short Tale About the Family, the Fox, and the Moxon</h1>
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<h3>L. B. Cebik, W4RNL</h3>
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<p>The number of amateur radio activities in which one can involve all family members, whether or not licensed, is quite large. Field Day comes to mind, with a strong communal sense pervading the operating positions, the picnic tables, and the play area for children. However, my thoughts are drawn to the idea of some special activities in which there is mutual activity between parent and child, to the near exclusion of all else. The activities should let the child participate and give plenty of time for simple togetherness between the family members. Of course, "simple togetherness" is never simple, but involves all of the details of living that make family relationships so natural in their complexity and so complex in their naturalness.</p>
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<p>One such activity is fox-hunting: seeking out the hidden transmitter on VHF--usually 2 meters--by direction finding techniques that range from the simple to the sophisticated. There are periods of detection, in which one listens for and finds the direction of the hidden transmitter. Then there are periods of driving toward it--or at least thinking that one is driving toward the transmitter. These periods are perfect for that combination of ham and non-ham conversations that weave together a hobby and whatever is most important to the family members at the moment. The alternating detection and driving periods build toward a climax: the approach and actual discovery of the transmitter location. Finally, there is family triumph, as all shore the successful climax of the effort. Even if the work does not fall into the prize-winning category, the success is sufficient for all to share.</p>
|
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<blockquote>
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If this little account sounds a bit glorified, let me share a bit of correspondence: Just a quick note to say thanks for your contribution to the Amateur Radio Community. I built a variation of your 2-meter Moxon antenna design and used it at the local Amateur Radio Club fox hunt - on Saturday, May 5, 2001.
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My son (who has Downs Syndrome) and I came in second place in only 35 minutes! This was our first Fox Hunt. We were beat only by a team of engineering students who do this sort of thing as a regular pass time. The third place team came in at three times the time.
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Much of our success was due to the Moxon antenna, which I scaled to the exact fox frequency using EZNEC. I was actually startled at the depth of the null. Your antenna design and my son's compass brought us to within 20 feet of the "fox" with only 4 readings!
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Thanks again. My son is very proud of the second place award he was given for our effort!
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<p>I have removed the names of the individuals, but left in all of the other details. Similar parent-child mutual activities are certainly possible, and the benefits--for fully able and for challenged children--are likely impossible to catalog. Even sharing the frustration of not winning a prize and demonstrating the will to try again next time can benefit a youngster of any age.</p>
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<center>
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<h4>Building a Fox-Hunt Moxon Rectangle</h4>
|
||||
</center>For those who might like to try fox hunting as a family adventure, here is a run down on one way to build a good Moxon rectangle. <b>Fig. 1</b> shows the basic outline of a Moxon rectangle for 146 MHz using 3/16" aluminum rod elements. The most critical dimension is the gap between the driver and the reflector. It is desirable to set the element pieces to the correct length as the first act in building.
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<p>The antenna and support details appear in <b>Fig. 2</b>. Looking at details B-B and C-C, we can see the plan of assembly and feeding. The antenna will consist of 4 rods, each threaded to 10-24 on one end. The driver will have pairs of 10-24 stainless or aluminum nuts to hold terminal rings from the feedline. The reflector half-elements will join in a stainless steel coupling nut (a short piece threaded all the way through). You can purchase these or make one from a small piece of 1/2" by 1/2" aluminum stock. Simply drill though the piece from end to end and tap the required 10-24 threading.</p>
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<p>My favorite antenna support material is Schedule 40 PVC. As frequency increases, I like to minimize contact with the material. It would appear that Schedule 40 PVC varies in exact composition from one part of the US to another. In some places, UV retardants are effective, while in others, they are either ineffective or non-existent. Likewise, RF characteristics may vary from one manufacturer to another. By minimizing contact with the elements, any RF deficiencies in the PVC have little or no effect on the antenna.</p>
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<p>In</p>
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<p>, you can see the scheme I used. 1/2" nominal PVC is glued into a T, with elbows pointing upward in the sketch. The elements pass through end caps. These caps and the pipe stubs necessary to cement them to the elbows permit the use of set screws that pass through threaded holes in the double thickness of PVC. With threading that deep, set screws work well, although other methods can be used to ensure that the element do not move. One system that also works is to use short pieces of plastic tubing over the rods between the PVC supports and the nuts.</p>
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<p><b>Fig. 2</b> also shows a center Tee fitting for connection to a mast. This fitting is optional and would be suited more to the horizontal use of the antenna. Lets look at the alternative that I actually used in <b>Fig. 3</b>. When vertically orienting the Moxon, a rear support system is very useful. We can make one up out of more PVC fittings and pipe. For my test antenna, I used a single PVC pipe section between elements, with the reflector center point holding a 4-way cross fitting. Another pipe stub proceeds rearward and friction fits into the Tee in the support. I drilled two sets of holes through the stub so that I could change the antenna's orientation from vertical to horizontal and back by removing only a single bolt.</p>
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||||
<p>The support consists of a straight section and an angular section, forming a strong triangle. The terminating sections are 1.25" to 1/2" adapters sections. The antenna support pipes fit into the 1/2" side ports, while the 1.25" through sections receive piping of the same size to fit over a standard TV mast. Clamps mounts are shown, although one might also use set screws. The space between the upper and lower adapters can consist of the short clamps pipe sections shown, or the space can be filled with a single section of 1.25" nominal PVC. The resulting structure has a bit of flexibility, but stands up to abuse very well.</p>
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||||
<p>One of the keys to building a good PVC structure is to be prepared in advance for aligning portions of the structure that must be at right angles or parallel to each other. PVC cement may give you as little as 15 seconds before glued parts become immovable. I have cataloged a number of right-angle junctions in my shop that are suitable for aligning PVC pieces. Among them are legs and other supports for the work bench. If a Tee or an elbow requires fitting, I usually put a scrap of pipe dry into the open end. The longer section makes alignment much easier than a junction stub. I simply glue the junction in question and then press it against my sturdy pre-formed angle.</p>
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||||
<p>For the element mountings in their caps, I first cemented the junction pipe stubs in the caps. (These stubs will be glued into the elbows later.) Then I drilled the caps and stubs together. A drill press makes easy work of centering the holes on both sides of each cap. Next, I pushed each pair of caps over a scrap of 3/16" diameter rod to keep them aligned while cementing each one into its corresponding elbow joint. These and similar techniques simplify making almost any conceivable structure from PVC parts.</p>
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||||
<p>Bending rod elements is most simply done with a copper tubing bender, a small device that can be found at most hardware depots. The bender will make a 1" radius bend. 3/16" rod and smaller will easily handle bends of this radius with no noticeable weakening or visible cracks. I first cut each element section to length and mark the point (away from the threaded end) that corresponds to one half the side-to-side width. I placed this point in the middle of the 90-degree bend. This technique has yielded results identical to those predicted by sharp-cornered computer models of the antenna.</p>
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||||
<p>There are many ways to construct the Moxon for VHF use. The sample shown here is only one of them. For an alternative construction method, with many useful additional notes on the design, see "A Compact Two-Element, 2-Meter Beam" by Lee Lumpkin, KB8WEV, and Bob Cerrito, WA1FXT. The article appeared in the January, 2000, <i>QST</i>, pp. 60-63. Their version used #10 AWG wire, which is just over 0.1" in diameter.</p>
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||||
<p>The Moxon can be scaled for 220 or 440 MHz use--so long as one remembers also to rescale the element diameter or to make appropriate adjustments in dimensions if a scaled element cannot be used. The thinner the wire relative to the original, the smaller the gap; the fatter the element, the wide the gap. And other dimensions will also alter slightly to obtain the maximum null at the new design frequency, with the resonant point slightly lower to obtain full operational coverage of a band or the subsection of interest.</p>
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<h4>Why a Moxon?</h4>
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||||
</center>The basic azimuth pattern of a Moxon shows, at its design frequency, a deep null, with some forward gain. For most VHF uses, it is the pattern shape, with its very high front-to-rear ratio, that holds more interest than the antenna's gain. <b>Fig. 4</b> reveals the azimuth pattern of a 2-meter Moxon when the antenna is vertically oriented and, hence, vertically polarized. The model is designed for 146 MHz and the deepest null occurs only in the vicinity of the design frequency. Hence, you may wish to scale the antenna for the precise frequency on which fox hunts are conducted in your area.
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<p>For general use--horizontally or vertically, the front-to-rear ratio--accounting for the full rear quadrant--is very good anywhere in the band. Moreover, as <b>Fig. 5</b> shows, the antenna has a very broad operating bandwidth. The SWR curve never reaches 1.4:1 anywhere in the band.</p>
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<p>The first task after placing all of the Moxon element pieces in their PVC holders and attaching the feedline is to adjust and temporarily lock the gaps between element ends. The first rod Moxon showed a 50-Ohm resonance at about 145.75 MHz, just about where the design placed it.</p>
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||||
<p>It is usually dangerous to assume that, because an antenna is tuned to provide a good match for the feedline, it will also show the modeled gain and front-to-back ratio. However, in this case, the antenna geometry that determines the source impedance also determines the pattern shape. Since the elements were uniform in diameter, there was no reason to expect any performance surprises. Therefore, I locked the assembly tight and moved on to performance tests.</p>
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||||
<p>The Knoxville, TN, area has repeaters from close to 145 MHz up to nearly 148 MHz. All of them are easily accessed and heard at full quieting from my location with only a low elevation ground-plane vertical. In fact, a telescoping whip on my hand-helds will access all of our main repeaters. On a 15' mast, the Moxon made "telephone" copy of all of the repeaters when the antenna pointed anywhere near the forward direction to them. A distant repeater that I hear poorly on a vertical was now full quieting. The Moxon's gain can make a difference for signals at the FM threshold.</p>
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<p>When the antenna faced away from the repeaters, only 1 of 6 repeaters that I checked could still be heard, and then at far less than full quieting. I could not access any of the repeaters with 5 watts of power--the limit of my gear at the time. I ran additional tests using two hand-helds on simplex across the FM portion of the band. Differences in the patterns at the band edges and at the design frequency were not especially detectable at distances of a quarter mile. Face forward, communications was easy and full quieting. With the antenna pointed in the other direction, communications was virtually impossible.</p>
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<p>The proto-type vertical rod Moxon has proven a very effective antenna at blocking unwanted signals from the rear. In fox-hunting, it is precisely the deep null to the rear that let's us take a bearing on the hidden fox transmitter. Whether distant from the fox or close in, the deep null--combined with a compass--will serve well in locating the fox's direction without any ambiguity.</p>
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<p>I shall leave the details of setting up the Moxon for mobile fox-hunting to your ingenuity. Some folks use a system involving a auto-window mount support, and it may also contain a large compass rose. Set the compass rose with a compass at each stop or reading period and then take the null of the fox. Using an antenna backwards takes a little getting used to, but quickly results in accurate bearings on the fox. Now if only the roads went to the fox as the crow flies, we could win every fox hunt in a flash (well, a slow flash within the speed limits).</p>
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<center>
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<h4>Back to the Family</h4>
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</center>I have dwelt on building a Moxon for fox-hunting to show that with a little effort, one can set up a family activity without much cost. It takes equal effort to set up the activity so that it accomplishes your family goals. You may wish to try an initial fox-hunt alone to get used to the the antenna and the other aspects of how the hunt is conducted. Then you can concentrate on the total activity, including the involvement of any children, when the family takes to the fox's trail.
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<p>As in the communications that I received, you can let the child operate the antenna and compass, building their confidence in their abilities to contribute to family success. I remain convinced that the self-confidence of children as they grow older stems not solely from succeeding in games and activities with their peers. It also grows with every successful contribution they make to the success of any activity that the family deems to be important. As well, successful contributions to the fox hunt may also intensify their interest in amateur radio as a life-long means of making contributions to the larger family that we call community and society.</p>
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<p>Fox-hunting is not the only way to achieve such goals, but it is a good case in point. Amateur radio is filled with opportunities for service and for full family participation that includes both the licensed and non-licensed members. I am indebted to a father and son for reminding me of this important aspect of our avocation.</p>
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<p><i>From</i> Proceedings of the 2002 National ARRL Education Workshop<i>, (Newington: ARRL, 2002), pp. 95-99. © L. B. Cebik, W4RNL. Data may be used for personal purposes, but may not be reproduced for publication in print or any other medium without permission of the author.</i></p>
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<p><a href="edu.html"><img src="../images/return.gif" align="bottom" width="40" height="40"> Go to Educational Notes Index</a></p>
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<p class="topics-footer">Topics: <a href='../topics.html#education'>Education</a>, <a href='../topics.html#moxon'>Moxon</a>, <a href='../topics.html#pvc'>PVC</a></p><br>
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<h1><img src="../images/edu.gif" align="left" width="100" height="83" border="2" vspace="5" hspace="9"> <img src="../images/w4rnlwwr.gif" align="right" width="99" height="83" border="2" vspace="5" hspace="9"> The Blackboard Jumble</h1>
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<h3>L. B. Cebik, W4RNL</h3>
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Teaching aids for amateur radio classes are within easy reach of almost every instructor. Less easily reached is an understanding of how to make the very best use of each kind of device to help students absorb, retain, and interconnect the bewildering array of wonderful information handed out in class. From the point of view of the ham instructor, who may not have long experience in the classroom, choices among teaching aids may seem arbitrary. Use the chalk, if it is handy. Make up a batch of overhead transparencies or large charts to save class time. Photocopy or create reams of handouts so students can carry home reinforcements of the class lessons. Box up a collection of components, power sources, and meters to demonstrate various principles. Such is the stuff of teaching.
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<p>After a few classes, an idea begins to develop: each kind of teaching aid has its own best use. If only I had realized this before my first class, I might have been more effective in getting my students to truly understand the things I take for granted in amateur radio. Even the ubiquitous blackboard that is available in most classrooms (although it is often green today) has its own special strengths in teaching. The jumble of writing crammed into every corner of the surface, with circuit and block diagrams plopped here and there, just has to stop and get organized. But how?</p>
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<p>My own experience in 30 years of teaching both ham radio and other subjects suggests that the answer to this question comes in two parts. First, we need a general idea of the best way to use each of the generic types of teaching aids. Just as our wood shops have many different tools, each with its own set of purposes, so too, not every teaching tool is good for every teaching job. Once we understand these basics, then we can begin the main task: to make the blackboard something more than a catch-all for everything that does not seem to have a better home. We shall discover that, despite its reputation for being old-fashioned, the blackboard is an excellent teaching tool for special tasks that none of the more modern teaching aids can do quite as well.</p>
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<h3>COMMON TYPES OF TEACHING AIDS</h3>There is such a large assortment of teaching aids that we cannot possibly deal with all of them here. Let us specify that the kinds of teaching aids of most concern here are those that help us along in the course of teaching a certain lesson plan, perhaps something about basic electrical principles. Films and videotapes that might teach the whole lesson for us are thus set aside for now. So too are numerous other learning activities that might also have a place in the teaching schedule, for example, guest experts on certain modes of operating, hands-on lessons in soldering circuit boards or making wire antennas, and many others.
|
||||
<p>Still, there are at least four general categories of teaching aids we might use in everyday fashion: handouts, overhead transparencies and other pre-prepared charts, demonstrations, and our old friend, the chalkboard. Each of these has a place in reinforcing lessons and in supplementing the class textbook. Let's take a brief look at each category.</p>
|
||||
<p>1. <b>Handouts</b>. With easy access to photocopy machines and services and with a computer to invent new collections of ideas, instructors are often tempted to inundate their students with handouts. Too many sheets, however, can be as bad as none at all. The student drowns in a sea of words, overwhelmed rather than enlightened. Reprints, extracts, outlines, and charts--usually handed out at either the beginning or the end of class- -fill the student's notebook. But does the information fill his or her head in a useful way? The object of a handout should be to organize special information, either in class or later.</p>
|
||||
<p>My own preference (and certainly there is much room for other ways of doing things) is to use handouts for two main purposes: to outline the lesson so that students can follow along and keep their place and to provide special collections of information that organize data in useful ways that our classroom text does not. The idea of a class-organizing outline is fairly straightforward and may include references to the text pages covered, exam questions covered (if relevant), and possibly suggestions for further reading, study, or experimentation. Special collections of data require a word or two more.</p>
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<table border="3" cellpadding="3" cellspacing="5">
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<caption align="bottom">
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Fig. 1. Sample partial handout on electrical phenomena and units of measure. The actual handout would include more entries and additional information.
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<tr>
|
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<th align="left" valign="top" nowrap>Electrical Phenomenon</th>
|
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<th align="center" valign="top" nowrap>Abbrev.</th>
|
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<th align="left" valign="top" nowrap>Basic Unit of Measure</th>
|
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<th align="center" valign="top" nowrap>Abbrev.</th>
|
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<th align="left" valign="top" nowrap>Common Fractional Units</th>
|
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|
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<td align="left" valign="top">Voltage; or electromotive force (e.m.f.); also called Tension or Pressue</td>
|
||||
<td align="center" valign="top">E</td>
|
||||
<td align="left" valign="top">Volt</td>
|
||||
<td align="center" valign="top">V</td>
|
||||
<td align="left" valign="top">mV (milliVolts), µV (microVolts) [both common in receiver work]; kV (kiloVolts) [common in power amplifier work and in electrical power transmission line work]</td>
|
||||
</tr>
|
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<tr>
|
||||
<td align="left" valign="top">Current</td>
|
||||
<td align="center" valign="top">I</td>
|
||||
<td align="left" valign="top">Ampere (Amp for short)</td>
|
||||
<td align="center" valign="top">A</td>
|
||||
<td align="left" valign="top">mA (milliAmps), µA (microAmps) [again, both common in receiver and other low power work]</td>
|
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</tr>
|
||||
<tr>
|
||||
<td align="left" valign="top">Resistance</td>
|
||||
<td align="center" valign="top">R</td>
|
||||
<td align="left" valign="top">Ohm</td>
|
||||
<td align="center" valign="top">Ohm</td>
|
||||
<td align="left" valign="top">kOhm (kilOhms), MOhm (MegOhms) [common resistance values in all work]</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td align="left" valign="top">Capacitance</td>
|
||||
<td align="center" valign="top">C</td>
|
||||
<td align="left" valign="top">Farad</td>
|
||||
<td align="center" valign="top">F</td>
|
||||
<td align="left" valign="top">µF (microFarads) [power supply, audio, and timing capacitors when in whole numbers; by-pass capacitors when expressed as 0.XX values]; pF (picoFarads) [most common in HF tuned circuits and filters]</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td align="left" valign="top">Inductance</td>
|
||||
<td align="center" valign="top">L</td>
|
||||
<td align="left" valign="top">Henry</td>
|
||||
<td align="center" valign="top">H</td>
|
||||
<td align="left" valign="top">mH (milliHenries) [common in audio frequency circuits and some RF chokes]; µH (microHenries) [HF and VHF RF circuits]</td>
|
||||
</tr>
|
||||
</table>
|
||||
<p>Consider Fig. 1, a partial table of basic electrical phenomena, units of measure, and abbreviations. Anyone can extend and complete this table to the exact degree needed by the students of any particular class, which is one important dimension of handouts: gear them to the exact needs of the students, not to some general parameters of electronics. Different classes, say, for novices and technicians as opposed to extras, may need different information or levels of information.</p>
|
||||
<p>Handouts are also useful for including important bits of information passed out verbally in the classroom, and they can key a remembrance of explanations. For example, listing the alternative words for voltage might help a student remember that the British like the word "pressure" and thus prevent a confusion if that person reads an R.S.G.B. publication. The student might also remember what is "tense" about a high tension line. In this way, the student begins to draw into a more comprehensive circle the bits and pieces of electrical terminology he or she has met along life's way.</p>
|
||||
<p>2. <b>Preprepared Charts</b>. Charts that the instructor brings to class, whether on paper or as overhead transparencies, should have a different look than handouts. They have a different purpose, namely, hitting and organizing the critical high points in any body of information. Comparing Fig. 1 and Fig. 2 shows something of the difference in appearance. The transparency has less information on it, but the information it does have stands out in higher relief.</p>
|
||||
<center>
|
||||
<table border="3" cellpadding="3" cellspacing="5">
|
||||
<caption align="bottom">
|
||||
Fig. 2. Sample of a partially finished table used as an overhead transparency or as developed on a blackboard. See text for techniques of development.
|
||||
</caption>
|
||||
<tr>
|
||||
<th align="left" valign="top" nowrap>Electrical Phenomenon</th>
|
||||
<th align="center" valign="top" nowrap>Abbrev.</th>
|
||||
<th align="left" valign="top" nowrap>Basic Unit<br>
|
||||
of Measure</th>
|
||||
<th align="center" valign="top" nowrap>Abbrev.</th>
|
||||
<th align="left" valign="top" nowrap>Common<br>
|
||||
Fractional Units</th>
|
||||
</tr>
|
||||
<tr>
|
||||
<td align="left" valign="top">Voltage or electromotive<br>
|
||||
force (e.m.f.)</td>
|
||||
<td align="center" valign="top">E</td>
|
||||
<td align="left" valign="top">Volt</td>
|
||||
<td align="center" valign="top">V</td>
|
||||
<td align="left" valign="top">mV, µV, kV</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td align="left" valign="top">Current</td>
|
||||
<td align="center" valign="top">I</td>
|
||||
<td align="left" valign="top">Ampere</td>
|
||||
<td align="center" valign="top">A</td>
|
||||
<td align="left" valign="top">mA, µA</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td align="left" valign="top">Resistance</td>
|
||||
<td align="center" valign="top">R</td>
|
||||
<td align="left" valign="top">Ohm</td>
|
||||
<td align="center" valign="top">Ohm</td>
|
||||
<td align="left" valign="top">kOhm, MOhm</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td align="left" valign="top">Capacitance</td>
|
||||
<td align="center" valign="top">C</td>
|
||||
<td align="left" valign="top">Farad</td>
|
||||
<td align="center" valign="top">F</td>
|
||||
<td align="left" valign="top">µF, pF</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td align="left" valign="top">Inductance</td>
|
||||
<td align="center" valign="top">L</td>
|
||||
<td align="left" valign="top">Henry</td>
|
||||
<td align="center" valign="top">H</td>
|
||||
<td align="left" valign="top">mH, µH</td>
|
||||
</tr>
|
||||
</table>
|
||||
</center>
|
||||
<p>Of course, a good chart or transparency should have lettering large enough for all to see. That is why photocopying book pages onto transparencies often fails to help students in class: they just cannot read the text comfortably. However, computers with bold, large, vivid print fonts let you create truly striking transparency masters.</p>
|
||||
<p>Moreover, the chart or transparency is never a substitute for the presence and activity of the teacher. Only the teacher can look the students in the eye and see confusions and questions the person is too shy to ask. Also, it takes a teacher to show the students how to navigate a chart or table full of information. As a matter of personal preference, I would use a finished table like Fig. 2 only as a review sheet, not as my primary aid to teaching the information. For that task, I prefer a blackboard (for reasons that will appear in just a few more paragraphs).</p>
|
||||
<p>For more excellent information on using transparencies, see an earlier volume of this series, The <i>ARRL National Educational Workshop</i>, specifically, 1992. Chester S. Bowles, KD1AP, does an excellent job of providing tips on making and using these charts in his article, "Creating and Using Overhead Transparencies," on pages 21-25.</p>
|
||||
<p>3. <b>Demonstrations</b>. Demonstrations come in many forms, from showing amateur communications techniques with real equipment to giving students the chance to practice soldering circuits. The keys to effective demonstrations are simplicity and size. First, do not try to cover too many things in one demonstration. Teaching the entire instruction language of Packet on the first demonstration repels rather than attracts future users. Likewise, introducing students to vector calculations of resultant currents in AC-powered circuits with resistance and reactance as their first encounter with Ohm's Law will create more fog than light.</p>
|
||||
<p>Demonstrations must also be sized to the class. A teacher's desktop demonstration of Ohm's law should not use an AAA battery, 1/8-watt resistor, and a pocket VOM, unless the students can each spend some time peering at the setup, hopefully through a magnifying glass. Demonstrations for the class must be large, so that everyone can see well. Or, they must be rigged for passing around the room or being viewed by each student in turn. Rush no one and be ready to answer every question.</p>
|
||||
<p>Review past editions of the <i>Workshop</i> proceedings and other instructional aides produced by the League for some excellent ideas on demonstrations. Many, if not most, of the ideas have come from teachers in the field.</p>
|
||||
<p>4. <b>Blackboards</b>. Is there any work left for the board? The answer is yes. In fact, even if an instructor spends months in preparing his or her ideas, handouts, transparencies, and demonstrations, he or she will spend more time working with the black-, green-, or chalkboard (or the whiteboard with its marker pens) than with all the other teaching aids combined.</p>
|
||||
<p>The most striking feature about a blackboard is that it begins blank (and hopefully cleanly erased by the preceding user). It is ready for anything, whether or not anticipated. No matter how many calculations you prepare for the class on Ohm's Law or resistors in parallel, someone may ask a question that requires one more example. No matter how complete a chart of schematic diagram symbols you give the class, someone will ask about the one not on the list. There are words you thought everyone knew, until you discover a few students spelling "mho" as "mo." Names and addresses of parts and equipment dealers will inevitably be needed one week prior to their planned introduction into the class. Even if you think that there are better methods for presenting certain information, very often the blackboard is the only handy way.</p>
|
||||
<p>The other most striking feature about blackboard work is that you create it as you go. The blackboard is an ideal tool for developing ideas and information in a well-calculated progression, one element at a time. With a marker pen and a blank transparency, we can capture some of this special talent on an overhead projector. I have known wheelchair-bound instructors who have successfully taught everything from math to political science this way. But they have all wished they could have a blackboard instead.</p>
|
||||
<p>The reasons for their blackboard fantasy are two: the position and the eraser. Blackboard writers stand in front of the class and can keep an eye on students to see their responses. Moreover, the chalk eraser corrects errors and permits modifications with the greatest of ease. Combined with some forethought about where on the board to put things and with a sense of neatness to keep material in good order, the blackboard, its chalk, and its eraser provide a tool that permits students to see ideas develop, whether in terms of words, in terms of calculations, or in terms of pictures.</p>
|
||||
<h3>THE BOARD AS A DEVELOPMENTAL TOOL</h3>A table saw is an excellent device for ruining perfectly good pieces of wood until we learn how most effectively to use it. Likewise, a blackboard can ruin perfectly good information if we let the data pour forth in a jumble with little rhyme or reason. One of the best ways to avoid blackboard jumble is to think about the board as a method of showing how ideas develop, how they emerge, how they combine to make more complete packages.
|
||||
<p>The blackboard, however, cannot substitute for the teacher. Rather, the teacher develops ideas, with the blackboard as his or her developmental partner. Words, together with pictures or writing, provide a reinforced presentation of ideas in the order needed by students for understanding. One of the beauties of the blackboard is that the picture or the writing can precede, follow, or be simultaneous with the talk, according to which order produces the strongest response. There is no general rule here, but experience will gradually give one a sense of the correct order.</p>
|
||||
<p>To see more clearly what good board use requires and to gain a better appreciation of what blackboards can do for teachers, let's take three examples, one each from the worlds of words, calculations, and diagrams. From these examples will spring all the extrapolations you need to use your board more effectively.</p>
|
||||
<p>1. <b>Tables of Terms</b>. Fig. 1 and Fig. 2, shown earlier, represent partial views of complete charts of basic electrical terms for Novices and Technicians. Both the handout and the transparency versions had good uses, but neither seems best for the act of teaching the terms themselves in the context of a classroom. One purpose of the exercise is to teach students to avoid confusing the name of the phenomenon and its abbreviation with the name of the unit of measure and its abbreviation. That requires a student to hear and see each type of term used in its own context. That way, each type of term forms the right language linkages for later confident use and recognition.</p>
|
||||
<p>For this reason, I prefer to develop the table of terms in the figures on the blackboard. The order of development goes something like this:</p>
|
||||
<p><b>Step 1</b>. Put the column headings on the board, along with explanations of why the chart requires 5 columns. This task involves distinguishing phenomena from units of measure, with analogies to common measures. For example, length has more than one basic unit of measure (feet or meters), and we might see a blueprint with the notation "L (meaning length) = 3'6" or something similar. When terms are brand new, as they often are for potential hams, this sorting process may be critical for preventing confusions before they occur.</p>
|
||||
<p><b>Step 2</b>. Introduce the first term, in this case, voltage or electromotive force. As I explain e.m.f., with some sense of what the phenomena is, I introduce the abbreviation, E, so students will see its connection. Then I add some remarks on tension and pressure so that students can coalesce similar ideas with multiple names under a single heading.</p>
|
||||
<p><b>Step 3</b>. Introduce the unit of measure, here the volt. Mentioning Volta and the naming of electronic units (but not many phenomena) after pioneers in the field gives students a handle for distinguishing unit terms from phenomenon terms. Most abbreviations come naturally.</p>
|
||||
<p><b>Step 4</b>. Introduce common fractional units, saying something about the contexts in which each might most commonly appear. In this case, each subunit can be explained with or without reference to a complete table of prefixes. Generally, I prefer not to get two tables going at once, since the development of each can interfere with the development of the other.</p>
|
||||
<p>Repeating the process for each term allows the table to grow on the board. If lessons on the basics of capacitance and inductances occur at a future class, I often prewrite the old elements of the table on the board just before class, leaving room to develop the new ones.</p>
|
||||
<p>Working with the developing table is just as important as developing it in the first place. Leave it on the board while you proceed to a related topic, perhaps Ohm's Law. Be sure to ask of your voltage source, "What is the voltage?" Someone is bound to answer, "6." That gives you the perfect opportunity to explain that numbers in electronics (excepting Q) require units of measure. In short, thinking developmentally about using the blackboard as an aid to teaching also allows you to unfold other important and related ideas.</p>
|
||||
<p>2. <b>Calculations</b>. Calculations are a natural for blackboard work. We can put up and erase example after example until students catch on to the idea. Nevertheless, we often do not use the board to full advantage from the teaching point of view. The student needs to understand every little--as well as big--step of a problem. What experience can take for granted and do automatically, teaching cannot. Developing a calculation is not just applying a formula, but as well it is a systematic process of thinking through a problem and reflecting that thinking in an orderly way on the board. Let's assume that we wish to show how to use Ohm's Law with all calculations made in basic units. The development might look like this:</p>
|
||||
<p><b>Step 1</b>. Lay out the sample measurements and the quantity we wish to find. Be consistent with units, either spelling them out or using the proper abbreviations. For example:<br></p>
|
||||
<pre> Measured voltage: 6 V
|
||||
Measured current: 3 mA
|
||||
Needed: Resistance in kOhms</pre>
|
||||
<p><b>Step 2</b>. Since we wish to make the calculation in basic units, that is, using Volts and Amps, we have a conversion step here. Whether we place the conversion next to the current entry or as another line of entry is optional so long as the work is neat and the student can see exactly what needs to be done.</p>
|
||||
<pre> Measured Current: 3 mA = 0.003 A</pre>
|
||||
<p><b>Step 3</b>. Calculate the resistance in basic units. Until students have mastered the algebraic transforms of Ohm's Law, place the correct form ahead of the fairly simple calculation. Then, let the students call out the answer.<br></p>
|
||||
<pre> R = E / I
|
||||
R = 6 V / 0.003 A
|
||||
R = 2000 Ohms</pre>
|
||||
<p><b>Step 4</b>. Finally, add the conversion step to put the answer in the correct units. Again, it is optional whether you use a new line or add the step to the numerical answer line, so long as students are clear about what you did and why.</p>
|
||||
<pre> R = 2000 Ohms or 2 kOhms</pre>
|
||||
<p>No law requires you to use a vertical scheme for developing classroom calculation, although it does permit alignment of critical elements in the calculation process. Call attention to these alignments to ensure that the student notices them. In other words, take nothing for granted about the naturalness of seeing things in the "common" way. That way is not yet common to most potential hams, but it will become common as a result of your teaching. Thus, it may prove most helpful to students to style your developing calculations to coincide with those the student is likely to see in his or her text and in amateur magazines and books.</p>
|
||||
<p>Once you have constructed enough calculations on the board, you may wish to provide students with some handouts with others: use worked, partially worked, and unworked samples. You can guide them through the process of finishing or making some of the calculations by labeling lines. To make the handout more effective, instruct the student to use a strip of paper to cover all the lines below the one he or she is reading. He or she should move to the next line only when the current one is fully understood. If understanding eludes the student, there is a question for the next class. Tell the student to mark the item and ask about it at the beginning of the next class.</p>
|
||||
<p>Many students are inclined to ask these questions in private, because they are embarrassed about not understanding. Unless the student is especially shy, encourage him or her to ask within the class. That way, everyone benefits from the explanation. My experience has taught me two important lessons. First, for everyone who asks a question, there are five others who refrain, even though they need to ask the very same question. Second, the only foolish question is the one unasked. Try to give your classes the sense of community in which everyone helps everyone else. That more than any other technique seems to break the barrier of silence.</p>
|
||||
<p>Of course, good answers contribute to a student's willingness to ask questions. When you can point to the developing progression of a calculation or a table of ideas to show precisely where something went wrong and how to make it right, you have a key ingredient of some very good answers.</p>
|
||||
<p>3. <b>Diagrams</b>. Most instructors (including me) tend to draw too fast on the blackboard. The simpler the diagram, the faster we draw. In turn, the faster we draw, the less students learn. Speed makes messy drawings. Even more importantly, speed turns our diagrams into mysteries: instead of clarifying principles, speedy drawings obscure them.</p>
|
||||
<p>Developmental thinking can change all that. By treating the drawing or schematic diagram as an orderly, emerging set of ideas, we can use it to familiarize students with the crucial elements that go into circuits and systems, all the while relating each step to basic principles, such as Ohm's Law. To see how this works, let's assume that we wish to illustrate Ohm's Law for a Novice class. We shall use a combination of ingredients, each developing the ideas in parallel. First, there is an experiment on the table using batteries or power supplies, some "unknown" resistors (say, 5-watters, with tape over the value markings), a voltmeter, an ammeter (or milliammeter), and an ohmmeter on the side to check our results.</p>
|
||||
<p>Second, there will be a set of calculations. For this example, we may use the ones just completed. Finally, we shall develop one or more circuit diagrams to help students relate schematic drawings to both real-world components and to the fundamental formulas of electronics. The one thing we shall leave out of this exercise is any sense of hurry.</p>
|
||||
<p>Even without the calculations and the experiment, the principles of developing diagrams still apply. Adding in the other elements reinforces the importance of letting diagrams emerge rather than just appear as a whole. The sample exercise might look like this:</p>
|
||||
<p><b>Step 1</b>. Start by setting up the power source, perhaps a battery. Then, begin the diagram by showing only the battery or power source. We shall follow this procedure at each step so that students can associate components with their schematic representations. Even if we have previously presented a list of schematic symbols and samples of their live counterparts, showing the correspondence in action can augment that past lesson and add to it a new dimension. Here, students will see the connections that make components into circuits.</p>
|
||||
<p>The first stage of our diagram on the board will thus look like this:</p>
|
||||
<center>
|
||||
<img src="edu2-1.gif" width="470" height="404" border="2" vspace="5" hspace="9">
|
||||
</center>
|
||||
<p><b>Step 2</b>. Add a switch to both the experiment and the diagram and explain its use. Not only will it make and break current flow for our tests, but it will also contribute to our safety in handling the components. So our diagram grows a bit:</p>
|
||||
<center>
|
||||
<img src="edu2-2.gif" width="473" height="405" border="2" vspace="5" hspace="9">
|
||||
</center>
|
||||
<p><b>Step 3</b>. Add a resistor to complete the circuit. This addition shows the basic units involved in our prospective calculation, even though we have yet to add the measuring devices.</p>
|
||||
<center>
|
||||
<img src="edu2-3.gif" width="473" height="405" border="2" vspace="5" hspace="9">
|
||||
</center>
|
||||
<p><b>Step 4</b>. If the students understand the basic idea of a complete circuit, we can then show and explain how the meters fit into the overall scheme. Place a meter across the resistor while explaining why voltmeters are used that way. Then interrupt the line near the resistor with a small erasure to insert the (milli)ammeter. It pays to ensure that students understand that current travels through the meter without significant resistance and hence does not materially affect the accuracy of our work.</p>
|
||||
<center>
|
||||
<img src="edu2-4.gif" width="474" height="406" border="2" vspace="5" hspace="9">
|
||||
</center>
|
||||
<p><b>Step 5</b>. You are now ready to switch on power and make some measurements. With the touch of an eraser and chalk, close the diagramed switch as you turn on the experiment. With the measurements, start the calculation procedure previously outlined. Add the values to the diagram, with the resistor value left open.</p>
|
||||
<center>
|
||||
<img src="edu2-5.gif" width="476" height="406" border="2" vspace="5" hspace="9">
|
||||
</center>
|
||||
<p><b>Step 6</b>. Moving through the steps of the calculation, we can arrive at the value of the resistor. To complete the task, we can erase the question mark and replace it with the value of the resistor. Now to check our work.</p>
|
||||
<p><b>Step 7</b>. Switch off the power, remove the resistor, and check its value with the ohmmeter. If the resistor was well marked, you can strip the tape to reveal its value. An explanation of tolerances may also be in order. You may even wish to diagram the ohmmeter hook-up.</p>
|
||||
<center>
|
||||
<img src="edu2-6.gif" width="471" height="405" border="2" vspace="5" hspace="9">
|
||||
</center>
|
||||
<p>You can now run through a collection of unknown resistors with the ease of placing them into the experimental circuit (with the power off) and going back to a question mark for the resistor value on the diagram. Make a mental note that you owe the students a later explanation of ohmmeters as devices that usually measure current with a preset voltage and only have a scale calibrated in Ohms.</p>
|
||||
<p>One advantage of developing our very simple diagram so carefully is that we can make changes without creating confusion. Suppose, for instance, we wish to illustrate the fact that Ohm's Law works equally well for DC and AC. In our experiment, we would replace the DC source with an AC source. Ideally, the source would be capable of an R.M.S. voltage that is equal to the voltage of the DC source. Then, students could expect the same current to flow as in the first experiment. We need, of course, meters for AC voltage and current.</p>
|
||||
<p>Changing our well-developed diagram is as easy as erasing the DC source and plugging in the AC source:</p>
|
||||
<center>
|
||||
<img src="edu2-7.gif" width="474" height="406" border="2" vspace="5" hspace="9">
|
||||
</center>
|
||||
<p>The technique also applies to replacing resistors with capacitors and with inductors to illustrate their ability to limit the flow of alternating current. Note, however, that although we can show the action of DC with a capacitor, if we use a sufficiently large electrolytic to demonstrate turn- on current, we cannot demonstrate the action of an inductor with DC without a current-limiting resistor in the circuit. Blown fuses generally do not make good demonstrations, although with the right preparation (being certain that only fuses will blow in our DC source), they can make a vivid demonstration of DC current through an inductor.</p>
|
||||
<p>Our look at the steps in the development of even the simplest circuit diagram has been patiently slow for two reasons. First, students need to see diagrams emerge in order to understand every aspect of the circuit they are seeing--often for the first time. Remember, the diagram is for the student, not for the instructor.</p>
|
||||
<p>Second, every step in the development of a diagram is a teaching opportunity, even if it may seem that the instructor is repeating something already said. The repetition, surrounded by something new to the student, reinforces the earlier lesson by connecting it to additional information and ideas. In this way, the student's understanding grows and develops in ways quite parallel to the development of our charts, our calculations, and our diagrams.</p>
|
||||
<p>Just as with any set of techniques, there are effective and ineffective ways of applying them. The ineffective way to use a chalkboard developmentally is simply to parrot the procedures mechanically. Or, one can get so wrapped up in replicating the procedure that one's attention is diverted from the students. Good principles become bad ideas if we do not use them wisely.</p>
|
||||
<p>Making the most of the developmental potential of a blackboard requires creativity and a bit of a flourish annexed to an understanding of the principles behind the procedures outlined here. For all the teaching aids available to us, instruction remains a person-to-person enterprise. Good procedures plus the best of the teacher's personality tend to make the best instruction and the best learning. Of course, a little neatness on the blackboard has never been known to hurt a thing. It is the first step to avoiding the dreaded blackboard jumble.</p>
|
||||
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|
||||
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|
||||
<br>
|
||||
<p><i>From</i> Proceedings of the 1993 National ARRL Education Workshop<i>, (Newington: ARRL, 1993), pp. 27-34 © L. B. Cebik, W4RNL. Data may be used for personal purposes, but may not be reproduced for publication in print or any other medium without permission of the author.</i></p>
|
||||
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<h1><img src="../images/edu.gif" align="left" width="100" height="83" border="2" vspace="5" hspace="9"> <img src="../images/w4rnlwwr.gif" align="right" width="99" height="83" border="2" vspace="5" hspace="9"> Beyond the License:<br>
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Teaching the Principles of Effective Station Design</h1>
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<h3>L. B. Cebik, W4RNL</h3>
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The most numerous questions ham students ask before and after class or during breaks concern equipment and antennas. The third most popular group of questions relate to station design, everything from finding a source of AC to running cables through the walls, from operating desks to special lighting. Every new ham wants an effective station, however modest the investment in equipment.
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<p>As an adjunct to preparing students for the license exams, we can teach station design more systematically than we currently do. Better teaching is often a matter of collecting and organizing material under a coherent set of principles. Ergonomics, the study of the human dimensions of the workplace, is not as organized as electronics. Hence, the principles are not absolute. However, we can organize the subject so that the student has a mental checklist of things to consider.</p>
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<p>The following notes are a step in the direction of organizing station design ideas in a way the student can use, master, and adapt to his or her particular circumstances. Their importance lies in the contribution they can make to the new ham's operating satisfaction and success. In some ways, then, they can be as important as a ham's selection of equipment and antenna and his or her knowledge of electronics and the regulations.</p>
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<p>We can group the basic principles of ham ergonomics into four major groups:</p>
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<ul>
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<li>Safety,</li>
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<li>The Operating Position,</li>
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<li>Personal Ergonomics, and</li>
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<li>The "Shack."</li>
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<p>Each category collects a number of subsidiary principles. Moreover, each idea requires adaptation to different types of operation and personal circumstance. For example, the operating position of an exclusive VHF packet operator will look quite different from that of a CW DXer. In these notes, we can cover only the high points of each category and hope they are clear enough to be applied to the new ham's real world and to the ham teacher's encounter with his or her student's questions.</p>
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<h3>SAFETY</h3>Safety should override every other thought about the ham shack, especially since amateur equipment is nowadays an integral part of the household. The matrix of safety has two dimensions. In one of them, we can divide the subject between safety to the operator and safety to others who may be nearby. In the other dimension, we can divide ham shack safety into electrical and mechanical components. For brevity, we shall focus on this latter dimension here.
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<p>1. <b>Electrical Safety</b>. Electrical safety has three major components: AC and DC power, RF currents, and RF radiation.</p>
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<p>a. <b>AC and DC Power Lines</b>: Since most equipment is well housed today, AC and DC power lines and junctions are generally well protected from casual and fatal contact. However, component failure does occur, and dangerous situations can arise at the operating position. Shorted bypass capacitors can make the equipment cases hot, and protective circuits may operate only if the house ground is effective.</p>
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<p>Every station, therefore, should have an effective ground, a short wide conductor connected to a deep ground rod or copper water pipe. The house ground should be periodically checked for effectiveness by measuring the voltage between the station ground and the third wire and the neutral wire of the station's AC outlet.</p>
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<p>All power cords--AC and also DC lines from independent power supplies to transceivers or amplifiers--should be completely insulated with no exposed contacts. Cords should be out of reach and not kinked in ways that promote insulation wear and eventual wire exposure.</p>
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<p>The wall sockets that supply AC power to the equipment should never be overloaded. Ideally, the station should have a separate 110-volt line with its own circuit breaker. In practice, this is usually not feasible. However, be certain that the circuit used by amateur equipment is not shared by heavy current users among the household appliances. If you add or plan to add a high-power amplifier requiring 220 volts, be sure it has its own circuit and breaker.</p>
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<p>There should be a master AC switch for the station, one that cuts power to all equipment. This may require building a master AC panel for the shack and instructing family members in its use. The panel must meet wiring codes, but the components are usually inexpensive. Such a panel with a master plug as well as switch once saved my life.</p>
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<p>b. <b>RF Currents</b>: RF currents can be exposed at terminals, cable junctions, open equipment, and antennas. The principles of solution are straightforward. Just as antennas should be high and out of reach of any person, so too, terminals should be inaccessible. Cable junctions should be inaccessible or shielded, or both. Open equipment should be closed.</p>
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<p>The dangers here are similar to those of contact with power lines: electrical shock and burns. In this respect, we can think of the antenna balun as a safety device in addition to its other functions. Antenna currents flowing on the outside of coax cables that make the equipment cases "hot" are not merely annoyances; they are dangers, especially to the uninitiated.</p>
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<p>c. <b>RF Radiation</b>: Related to, but not identical to, RF current dangers are potential dangers from exposure to RF radiation. The exact dangers are still under study, but safety dictates that all radiating structures (antennas) be as far away from human bodies as possible. The more power they radiate, the farther away from humans they should be. The higher the frequency, the more probable the danger for a given power and a given distance from the body.</p>
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<p>Expressed in these blank terms, the basic ideas can cause unnecessary fear of amateur operation. The proper way to present these ideas is as a search for better solutions to antenna placement challenges and for good decisions as to equipment power. Sensitizing new hams to radiation safety includes stirring their interest in reading the latest developments and findings in <i>QST</i> and other reputable journals.</p>
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<p>2. <b>Mechanical Safety</b>. As important to safe operation are the mechanical factors in a station. We can divide our thinking into two departments: physical dangers and security.</p>
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<p>a. <b>Physical Dangers</b>: A complete catalog of potential physical safety problems would require a book. The basic principle is simultaneously to protect people and equipment from damage by accidental contact with each other.</p>
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<p>One of the most common dangers is cable maze: the looping and twisting of cables under and near the equipment. Not only do people trip over cables, cables often attack the operator's feet, wrapping themselves around like vines. The equipment has crashed to the floor or the cables have broken before they turn loose. The solution to this problem is a cable trough at the rear of the operating table or under its rear lip. Hardware stores are full of hook-like devices that will hold cables in a free but neat bundle out of the way of unwary feet.</p>
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<p>Often overlooked by experienced as well as new hams is the physical danger that sharp corners and precariously balanced heavy equipment may present. It pays to recess all equipment so that bumps cannot knock the gear loose, damaging either the person who bumps it or the gear itself. Likewise, recessing equipment into consoles or shelves protects unwary body parts from cuts and gashes as they pass over sheet metal corners or sharp projections.</p>
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<p>b. <b>Security</b>: If you are lucky enough to be able to devote an entire room to the ham station, consider adding a lock to the door. If there are small children in the family, a sliding bolt well above their reach may be enough to keep small hands from getting into danger when no one is looking. Security also dictates a fire extinguisher in the station. It should be mounted in a handy location and be rated for electrical fires.</p>
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<p>More commonly, the modern ham station is located in a room that is shared with other family functions. As equipment shrinks, a very versatile set-up may require little more room than a personal computer. In this case, security moves from the door to the operating position. Consider putting the equipment in a unit with doors that you can lock when the station is not in use. You may even wish to build special ducts for the cables. The primary object is to secure the station from any entry that might remotely harm the innocent invader. The secondary--but also very important--goal is to protect the equipment from uneducated and unauthorized handling.</p>
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<p>Of course, the most safe and secure station is the one surrounded by educated adults and children. Not every family member may become a ham, but everyone in the family can learn to respect the station equipment, to know what to do in the event of an emergency, and to share both the successes and frustrations of amateur operations.</p>
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<h3>THE OPERATING POSITION</h3>The operating position consists of the arrangements of equipment and the supporting surfaces that permit the arrangement. There are innumerable individual variables that play a part in good station decisions: available space; funds; woodworking or finishing skills; and the modes, bands, and types of operation. However, a few general principles apply to almost all situations. They require that we look at the operating position from different angles.
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<p>1. <b>Furniture</b>. Since equipment is not self-supporting (the days of 6' rack panels are mostly gone), it requires a desk or console for support. Furniture fulfills at least two functions: support and storage. Desks have one support surface and usually many storage drawers. Computer consoles with upper shelving provide more support surfaces, but usually fewer storage drawers and shelves. Some consoles have doors that can safely secure the equipment and keep the electronics out of sight in a multi-purpose room.</p>
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<p>For larger layouts, unfinished doors supported by pedestals with shelves, cabinets, or drawer units provide up to 7' of operating room. I personally prefer wider doors (up to 36") to leave plenty of writing, keyboard, and elbow room in front with space for a cable trough behind. However, 30" doors work well for many installations.</p>
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<p>Of course, hams with extensive woodworking skills can develop custom furniture to support and protect their equipment functionally and beautifully. The U-shaped console is perhaps the most accessible arrangement for an extensive array of equipment. Plywood or laminated panels with cutouts and support shelves can shield equipment and cables from curious fingers while allowing good panel access in front and good air flow behind. A wheeled swivel chair is a must. More linear L-shaped arrangements are also serviceable.</p>
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<p>Effective operating requires not only that the furniture support the equipment, but that it supports it correctly relative to the operator. Correct support has two dimensions: the vertical and the horizontal (or elevation and azimuth, if you prefer).</p>
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<p>2. <b>Equipment and Accessories</b>. Equipping the station is a function of the primary operating interests of the new licensee. Although these notes are devoted to everything except the primary equipment, the best possible advice for the new ham is to leave room at the operating position for growth. New interests, hamfest bargains, and a host of other incentives will cause a station to grow.</p>
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<p>The other basic principle concerns our usual neglect of the space taken by station accessories. Telephones, microphones, keys and keyboards, logs, note paper, and many other operating needs often end up competing with elbow room at the operating position. Planning for these items in advance can make the difference between a discouraging mess and a clean, effective set-up that even has a safe corner for a coffee cup.</p>
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<p>In addition, every station needs close at hand a number of operating aids. Most of them are paper. Spare scratchpads, repeater directories, antenna bearing charts, ham magazines to read during quiet band times: these are typical of the paper aids that need both storage and access at the operating position. Spare fuses, an extra microphone, patch cable, and headsets are among the bulkier items that often need storage at the operating position. Desk drawers or shelves are a necessity.</p>
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<p>3. <b>The Vertical Perspective</b>. Seated at the operating position, we scan our equipment vertically. Fig 1 shows a general outline of the situation. There are three major areas of concern.</p>
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<img src="edu3-1.gif" width="451" height="424" border="2" vspace="5" hspace="9">
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<p>First, the heaviest equipment with the most used controls should be in the prime sight line and hand line. Auxiliary equipment with less used controls should be in the next tier, with visual monitors above. This arrangement is most relaxing for both the eyes and the arms. Note the room for a cable trough behind the equipment.</p>
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||||
<p>Second, visual angles should be as natural as possible. Note that the main piece of gear presents a flat face to the operator in his or her natural seated position. This facilitates reading out frequency, meter, and control settings. The equipment on the elevated shelves should not be higher than a lifted head can easily see.</p>
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<p>Third, the controls of the main gear are elevated for ease of adjustment with elbows on the table top. Achieving this goal often requires a sloped console base, since equipment bales are usually not long enough to do the job. The space under the base console is useful for storing papers, CW keys, and other items, for housing a master AC safety panel, and for meters and accessories.</p>
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<p>3. <b>The Horizontal Perspective</b>. Horizontally, equipment should ideally be laid out according to principles of focus, quadrant, and halo. Fig. 2 illustrates the three concepts with a typical modest HF station. VHF, SSTV, RTTY, packet and other specialized operations will have their own layouts, but three focus-quadrant-halo principles will still apply. Of course, most of us can only approximate the ideal.</p>
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<img src="edu3-2.gif" width="643" height="429" border="2" vspace="5" hspace="9">
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<p>a. <b>The Focal Area</b>: Central to the position is the main equipment of the operation, the gear that requires the closest attention to readouts and controls. Its centerline position and vertical placement where both eyes and hands can reach it are crucial to effective operation. In the HF illustration, the focal gear is the transceiver. In a VHF packet station, it might be the rig and the computer keyboard right in front of it.</p>
|
||||
<p>b. <b>The Quadrants</b>: Surrounding the focal area should be quadrants of related pieces of equipment. Around the center of Fig. 2 are 4 quadrants for transmitting, computer, antenna control, and speaker functions. Note that each functional quadrant groups together related equipment.</p>
|
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<p>Every quadrant assignment will be a compromise between operating needs and ideal equipment spacing. The weight of the amplifier with its power transformer demands support, while the lighter transmatch can be placed higher. If we assume that the computer is central to station operation, it needs a central position for monitor viewing, even though that may separate the transmatch from antenna control functions. If the computer is a peripheral device for occasional use, then it might go on the right, with the antenna functions moved to the center. In this example, the vertical computer case goes to the far left, with the monitor positioned centrally for easy reading. All of this, of course, presumes that the cables exit the station to the right of the position.</p>
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<p>The objectives of the quadrant principle are many. Related gear belongs together for minimal cable runs. The most handled equipment requires easiest, most direct access. Crucial monitors and readouts require the most direct eye contact. Power and RF cable directions can modify quadrant placement. Even being left- or right-handed can make a difference in deciding the best placement for each quadrant.</p>
|
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<p>c. <b>The Halo</b>: Around the quadrants, and beneath them, is a halo for all the miscellaneous items that go into operating a particular station. These include the telephone, the log, the mike, the key, the keyboard, operating aids, and often- used pieces of test equipment. Whatever the support system you use for your equipment, leave a little extra surface, shelf, and drawer space to keep needed extras close at hand. At my own station, a world globe sits atop the gear, and file drawers hold all sorts of paper work, including some magazines to read while waiting for a band to open. Finally, find a safe place in the halo area for your coffee cup or soft drink glass, well away from the rig and the keyboard.</p>
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<p>Combining furniture ideas along with vertical and horizontal perspectives of equipment placement is best done on paper first. Paper is light and cheap compared to the other items and permits a dozen changes without a single strained muscle. A little planning goes a long way toward comfortable and effective operation.</p>
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<h3>PERSONAL ERGONOMICS</h3>Many personal factors can affect the effectiveness of operation either positively or adversely. Only three will appear here, but they may suggest others to you.
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<p>1. <b>Seating</b>. A good chair is a must for any operating position. A good chair must support the base of the shoulders and the lower back. The length of the seat pad should support the legs, but not cut off circulation to the calves. The seat should be just high enough to support the thighs while leaving the feet on the floor, again, so as not to cut off blood in the back of the thighs. Fig. 3 illustrates these points.</p>
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<img src="edu3-3.gif" width="491" height="456" border="2" vspace="5" hspace="9">
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<p>Well-designed office chairs with seat and back adjustments often work well as ham operating chairs. The wheels are handy for turning as well as moving, but the base should be broad enough to prevent the chair from tipping over. If the chair has arms, they should not interfere with the operator's arms.</p>
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<p>These design features, of course, are idealizations. Some operators are only happy if they can hunker down in an old overstuffed chair, while others require a hard-bottom straight chair to help them stay alert. Whatever the choice, be sure to check yourself periodically to see if your chair is unnecessarily fatiguing you or interfering with what you want to do.</p>
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<p>If the shack area is large enough, leave room for an additional chair for observers and visiting operators. In part, that is a matter of ham hospitality. Additionally, the chair may be a good place for a potential ham in the family--spouse, sibling, child--to get close to the operation and feel a part of it. With attention to just a few details, every ham station can be a recruitment center for new hams.</p>
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<p>2. <b>Light</b>. Room lighting often leaves the operating position in the dark, or--what may be worse, in sharp dark shadows. If the operating position is near a wall, a central ceiling fixture often will not suffice to prevent eye strain. Yet, an equipment-filled operating desk or table often cannot find room for a lamp.</p>
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<p>Supplemental lighting may consist of either lamps at the operating position or a new ceiling fixture overhead. Either system will work if you attend to some basic principles. Lighting should be adequate, but diffused to prevent harsh shadows and blinding reflections on readout panels. Lamp shades should protect you from having to look directly at the light source. Since diffusers on light fixtures and lamps cut down on the light going in any given direction, start with a larger bulb, perhaps as much as 200 watts.</p>
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<p>The perfect lamp or fixture may not exist. Most lamps with diffusers stand straight up, but you may need a swing arm to place the light over the space between you and the equipment. In such cases, you may have to be inventive, combining elements from more than one source to create the perfect lamp or lamps.</p>
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<p>Use care both with fluorescent fixtures and with high-intensity lamps. Be sure you can withstand the type of light they produce for long periods before making either kind of fixture a permanent part of the shack. Remember: the goal is both good illumination and long-term eye comfort.</p>
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<p>3. <b>Ventilation</b>. Good air flow and temperature control are essential to operating comfort and good health. You should not sit in either a hot or a cold draft. Hence, do not place the operating desk or table over a heating or air conditioning vent. If the walls have air registers, be sure the air flow does not pass directly over you on its way either in or out.</p>
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<p>On the other hand, be sure that air can move around the operating position. Ventilation is necessary to carry heat from the equipment, and it must have somewhere to go. Likewise, operating comfort and efficiency are best if the temperature and humidity are reasonably constant without the air going stale. Hot or cold cul-de-sacs within a house or its basement are not the best places for an amateur station.</p>
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<p>Other amenities of personal comfort are largely a matter of taste. Places for a sink, coffee pot, cold drink storage, snacks, pillows, etc. have no general planning principles. Indeed, only two principles apply to these refinements: 1. if something is important to you, have it at hand or accessible; 2. if it can cause harm to the equipment by way of spillage, sharp points, and the like, do not make it too accessible.</p>
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<h3>THE "SHACK"</h3>The "shack" is an honorable and traditional word for wherever the operating position is. Long ago, the shack was a rough out-building, or an equally rough part of an attic or basement, known for its messy, smelly, and dangerous appearance. In modern times, the shack is most often a room or portion of a room where we set up our equipment, run our power and antenna cables, and do our operating. Every possible shack site needs a full evaluation to ensure it will work in the context of both our operating desires and our family's needs. Although these principles stress amateur operation, the family circumstances within which we enjoy our hobby require and deserve as much, if not more, attention. While making new friends around the area, the country, or the world, we should not alienate those who are closest to our hearts and responsibility.
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<p>1. <b>Site Inventory</b>. The first step in evaluating a room as a prospective shack is to diagram everything relevant to our operation. Fig. 4 illustrates a hypothetical room.</p>
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<p>The sketch in Fig. 4 provides information on everything in the room: heat registers, AC sockets and switches, existing lighting, window placement, and even door swing. It includes all the important dimensions. Additionally, the drawing says something about what adjoins the room, in this case a front room along one wall and a bathroom along the other. (The adjacent bathroom might well be an advantage to a contest operator.)</p>
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<p>The drawing does not limit itself to one floor of the house. In this case, the sketch shows relevant parts of the basement. These (or attic) details may be important when considering where to place the operating desk or table.</p>
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<p>For example, suppose your operating desk is 5'10" long by 2'8" wide. Antennas will be in the back yard. The outer wall with windows is not a good site, since the desk would cover the heat register. The 6' by 3' alcove is tempting, because it would snugly place the equipment in its own space. However, sounds from the equipment would reach the front room, and the cable runs would be a problem. Hence, the best position might be along the rear windowless outer wall with a basement window just below.</p>
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<p>The sketch does not tell us everything we need to know about the room. Be sure the walls have a pleasant appearance, since you will be seeing a lot of them while operating. Test the walls and ceiling for acoustics, and add sound dampening materials if appropriate. Measure window sill heights before placing furniture. Determine the clearance needed for passage though the room to and from the door. Check the walls for their ability to support any shelving or other construction you intend. Check the floor: Can you drill through unobtrusively for your cables? Do you need mats to dampen foot noise? It is easier to modify and perfect the station room before installing furniture and equipment than afterwards.</p>
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<p>2. <b>Cables</b>. To the room in Fig. 4, you may wish to add a 220 v. AC line to power the amplifier. Power cables must meet all applicable codes. Indeed, it will be wise to test the existing 110 v. AC socket. It should be a #12 2- wire plus ground circuit with a 20-Amp fuse or circuit breaker. Additionally, it should be as isolated as possible, with a minimum of other household equipment using the same breaker or fuse.</p>
|
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<p>Antenna cables may be the greatest challenge in the shack. One goal is to use the shortest feasible run of cable to the antennas. Assume for the sake of example that the antennas are in the back yard. Placing the operating table along the rear wall of Fig. 4 permits the cables to leave the shack through the floor and out the rear basement wall either through the basement window frame or through the perimeter joists. Alternatively, they may leave through the rear wall using PVC or other tubes packed with thermal insulation around the coax.</p>
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<p>The second goal is to make as few modifications as possible to the house. Save plugs from the hole cuts for reinstallation if you sell the house. In any event, be sure the cables have easy passage with no binding. Use enough cable to allow looping turns rather than sharp bends. Support the cable every few feet to prevent deformation from sagging.</p>
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<p>3. <b>The Rest of the Room</b>. Our 9' by 12' room would make an ideal shack if we could put all our radio activity and nothing else in the room. A quiet test bench with tools and an array of meters might go into the 3' by 6' alcove next to the door. Book and magazine shelves could go along the wall between the door and the operating position. Some comfortable chairs and reading lamps could go next to the windows. Or, a separate desk and computer station might go on either side wall for correspondence, QSLing, and other ham paperwork. The possibilities are nearly endless.</p>
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<p>As noted earlier in the discussion of the principles of security, only some of us are lucky enough to be able to devote an entire room to ham activities. In many instances, amateur radio will have to share space with other family enterprises. In that event, strive to keep the shack separated by a real or imaginary barrier. The barrier should keep objects and instruments --things like toys, tools, and small appliances--from entering the operating area. The barrier should also be a sound cushion to keep the bustling clatter of family life outside and the odd chatter of ham radio inside. If everyone in the family is educated to respect the barrier, it may work better than any wall. However, amateur radio is just one facet of family life. Sometimes it must give way to more pressing needs.</p>
|
||||
<p>4. <b>Maintenance</b>. Although shack maintenance deserves extensive discussion all by itself, perhaps a very few words here can alert the new ham to the need for continuing preservation of his or her ham investment. Maintenance has three major dimensions: clean-up, performance checks, and service. Cleaning up the operating position on a daily basis is somewhat of a drudge, but essential to the long life and neat appearance of the equipment and furniture. Gummy dust is an enemy to equipment, but easily avoided by routine wiping.</p>
|
||||
<p>Equipment ages and often loses performance so slowly that we do not notice. Periodically checking performance and keeping a record of those checks can often spot a problem before it becomes catastrophic. Received signal strength of local stations and power output measurements are the beginning of a good performance checklist. Although modern solid state digitalized equipment often requires less periodic servicing and alignment than older tube-type completely analog gear, plan some service money into the ham budget. These smaller amounts can save the cost of premature equipment replacement later on.</p>
|
||||
<h3>THE HUMAN DIMENSION</h3>Every list of principles for station design must be customized to the individual situation of the station designer. This brief introduction to the human and personal dimensions of station design is only a beginning. However, it should be sufficient to get any new ham started down the right road to effective operating--apart from the selection and mastery of the right equipment for the shack.
|
||||
<p>The shack is a composite of technical requirements and personal factors. The latter includes ourselves in terms of what we want out of a shack, our physical environment, our human environment, and--of course--our finances. For the lifelong ham, there never comes a time when something better cannot be done with or to the station.</p>
|
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<p>Shacks change with time, just as do operating interests and family circumstances. A dozen years down the road, the sophisticated customized station layout will surely be better than the first assemblage of equipment. But the first shack will linger in memory as the most exciting. It will be that place for the first contacts, the first successes, and the first frustrations. Therefore, the more instructors can do to pass along fundamental principles for good shack design, the more likely will be the prospect for that complex and refined station of the future.</p>
|
||||
<p>At the same time, putting together a ham shack draws upon skills and talents that go far beyond the technical electronics, the rules and regulations, and the good operating procedures we teach in licensing classes. And every classroom full of potential hams and upgrading licensees brings together an abundance of ability and knowledge, some of which may contribute to improving our own shacks. In the end, then, teaching the precepts of shack design involves as much listening as it does talking. Some of the best features in my own shack have come from the students I supposedly taught.</p>
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<p><i>From</i> Proceedings of the 1994 National ARRL Education Workshop<i>, (Newington: ARRL, 1994), pp. 15-22 © L. B. Cebik, W4RNL. Data may be used for personal purposes, but may not be reproduced for publication in print or any other medium without permission of the author.</i></p>
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<title>Teaching R.M.S. Values of AC Voltage and Current</title>
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<h1><img src="../images/edu.gif" align="left" width="100" height="83" border="2" vspace="5" hspace="9"> <img src="../images/w4rnlwwr.gif" align="right" width="99" height="83" border="2" vspace="5" hspace="9"> Why 0.707?<br>
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Teaching R.M.S. Values of AC Voltage and Current</h1>
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<h3>L. B. Cebik, W4RNL</h3>
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Introducing students to AC voltages and currents inevitably leads to a discussion of r.m.s. values. 1 volt r.m.s. or 1 amp r.m.s. equals 0.707 of 1 volt or amp peak voltage or current. When students ask, "Why 0.707?" we usually do as most of our texts did: we treat the student to a discussion of the root mean square of all the infinitesimal segments under a sine curve. The student memorizes the 1 unit r.m.s. = 0.707 unit peak relationship, but does not clearly tie together basic concepts in alternating current.
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<p>Granted, some students are content to memorize the relationship and let matters go. However, some want to get a handle on the relationships between peak and r.m.s. values of voltage and current. When I sense this, here is how I proceed. I turn around the explanation, starting with power and never mention r.m.s. until it is necessary to name the unit of measure. The task is not as easy as it appears. Many ham students have never mastered basic ideas in math and geometry. Therefore, the process of putting together the needed ideas often requires a few time-outs for reviewing or teaching some essential skills.</p>
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<p>However, the results are often startling: the exercise of tying together ideas on this topic often triggers repeat performances by the students with more advanced ideas in electronics. Seeing the student consolidate ideas on his or her own produces a feeling of teacher satisfaction that justifies the time and energy of taking the student on a detailed trip through basic ideas in alternating current.</p>
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<p>The following notes reflect how I generally proceed, including how I try to lead students around the pitfalls and hazards along the way. Although there is no magic in this step-by-step procedure, it does seem to work. The methods may be usefully adapted to other teaching efforts, both in basic subjects and in more advanced topics for license upgrades.</p>
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<h3>START WITH DC</h3>The first step in achieving a good understanding of AC is to be certain the student understands completely both Ohm's Law and the power law for DC. For our purposes, the most important form of Ohm's Law is<br>
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R = E / I (1)
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If we let R be some constant value, such as 1, then the ratio of E to I must be 1:1 or any other paired values, such as 2:2, 3:3, or 4:4.
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<p>To be sure the student understands this, use a schematic diagram or a test set-up configured as in Fig. 1. Since it is difficult to work out a test jig that allows both E and I to be equal without serious straining batteries, the schematic is often the best teaching aid, especially if supplemented by numerous sample calculations.</p>
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<img src="edu4-1.gif" width="623" height="324" border="2" vspace="5" hspace="9">
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Fig. 1 Basic DC circuits
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<p>For the DC lesson on Ohm's Law, digital voltmeters and ammeters can help plant the understanding that negative values of voltage and current are also proper for the E to I ratio. Value combinations of -2:-2, -4:-4, and -6:-6 all yield an R of 1 ohm, just as did the positive numbers. The only difference is the direction of electron travel through the meter and resistor.</p>
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<p>It is also important to stress that the values read from the meters are the levels of voltage and current at the instant of the reading. Neglecting real-instrument delays, every instantaneous reading represents an equally instantaneous level of voltage and current.</p>
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<p>Power, of course, is the rate of energy use. In transferring DC understanding to AC, we need also to be certain the student grasps the relationship of power to work or total energy use. Work is the rate of energy use multiplied by the time of usage. Whether we measure work in watt-seconds, watt-hours, or kilowatt-hours, the total electrical energy used by our circuit in Fig. 1 is reflected by the total heat generated and dissipated by the resistor. The longer we do work at a constant rate, the more energy we use. Ignoring the actual means used to measure house power use, the longer we run the electric heater, the more we pay the power company, which charges us for the total energy we use. If we ran that same heater off of batteries, we would see the same increase in cost by having to buy replacement batteries periodically.</p>
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<p>If the time factor is the same for every calculation, then power will be directly proportional to work. For a steady direct current through a constant value resistor with a constant voltage, power will be proportional to work. However, the student needs to get a grasp of the importance of time before approaching AC.</p>
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<p>For one thing, the DC-equivalents of AC phenomena depend on averaging certain values over at least one cycle. For another, energy use and its rate are also averages over time. The power formula,<br></p>
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P = E x I (2)
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</center><br>
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will be crucial to converting an understanding of DC into an equivalent understanding of AC. In fact, now is the time to begin labeling the elements of formulas so that the student can easily sort out ideas. So lets convert the form of our DC formulas to these:<br>
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R = Edc / Idc (3)
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and<br>
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Pdc = Edc x Idc (4)
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</center><br>
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R, of course, is simply anything that converts electrical energy into heat (or another form of energy) and therefore is not properly either AC or DC.
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<p>Note that in these formulas, I use the symbols for multiplication and division most familiar to ham students. With calculators and computers, students understand "/" to mean division, but if necessary, use the other division symbol.</p>
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<h3>GENERATING AC</h3>If the student is thoroughly at ease with the important concepts of DC given in the first step, then he or she is ready for the second step: the generation of standard forms of AC voltage and currents. Of course, an alternating current is any current that changes direction periodically. As teachers, we know of sine waves, square waves, triangle waves, and composite waveforms impossible to capture in a word. However, fundamental to AC concepts is circular motion, and the student will not be comfortable with AC without mastering its basic elements.
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<img src="edu4-2.gif" width="615" height="240" border="2" vspace="5" hspace="9">
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Fig. 2 AC generation
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<p>To introduce circular motion, I generally use a hypothetical generator which goes through one electrical cycle for every mechanical cycle. Fig. 2 illustrates how I use the generator. As the generator passes through the time-instant T0, its position vertically is also 0. The voltage and the current available to the load resistor is also 0. As the generator passes through T30, indicating the 30-degree point of travel around the circle, its elevation above 0 is a certain value. Here is where we must introduce just the amount of trigonometry needed to find out how high the arm is.</p>
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<p>Whether or not a student has had trigonometry, it is not difficult to convey the idea that the relationship of the side opposite to an angle of interest divided by the hypotenuse is a constant for any given angle. Then we can name the relationship the sine of the angle. Next, we can calculate the values of voltage for each of the indicated angles by punching out the sine of the angle on an inexpensive "scientific" calculator. If we let the hypotenuse of the triangle be 1 for all cases, then<br></p>
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E(angle) or I(angle) = sin(angle) (5)
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If the hypotenuse has a value other than 1, then the voltage or current become the sin of the angle multiplied by the actual value of the hypotenuse.
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<p>For these introductory examples, it is convenient to let both the hypotenuse of the triangles be 1 and the load resistor be 1 ohm. Numbers other than 1 will obscure the relationship of the sines of angles to the values of voltage and current, as well as to the value of power. When the lesson is over, you can inform the student that he or she has just had his or her first experience with the supposedly advanced concept of "normalized values."</p>
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<p>When introducing the idea of the instantaneous voltage or current, I try to use angles of 30 and 60 degrees, avoiding 45 degrees as much as possible. The aim here is to be sure the student is comfortable with circular motion and sines without prematurely including a half-developed notion of r.m.s. in the explanation.</p>
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<p>Although Fig. 2 shows only the first quadrant of motion, I generally take examples from all four quadrants. This shows that the values of voltage and current (with a purely resistive load) take both positive and negative values, and that they take them together. Here, we can relate these calculations of instantaneous voltage and current values to the DC measurements we made when reversing the direction of current flow.</p>
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<p>In fact, we can now show that Ohm's Law applies to instantaneously measured or calculated values of AC. At any given point in the path of motion,<br></p>
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R = Einst / Iinst (6)
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Additionally,<br>
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Pinst = Einst x Iinst (7)
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</center><br>
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<p>One of the most interesting sets of instantaneous values is the one produced by doing Ohm's Law at 90 degrees and again at 270 degrees. Since we let the hypotenuse be 1,<br></p>
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E90 = I90 = sin 90 = 1 (volt or amp),
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and<br>
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P90 = E90 x I90 = 1 x 1 = 1 watt.
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</center><br>
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Likewise,<br>
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E270 = I270 = sin 270 = -1 (volt or amp),
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</center><br>
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and<br>
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<center>
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P270 = E270 x I270 = -1 x -1 = 1 watt.
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</center><br>
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Since the voltage, current, and power never reach any higher values, we can rename these special values as the peak values. Thus, we have defined Epk, Ipk, and Ppk. At this moment, it is important to bring the student back to the diagram in Fig. 2 to relate the values the special points in the circular travel of the generator.
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<p>Just here, we can open some questions yet to be answered. Since the peak voltage, current, and power occur at only two points along the entire travel within the generator, they do not alone define the total energy produced by the generator and used by the resistor during an entire cycle. That value must be something less than the peak value. But how much less? Is there a systematic relationship between the peak voltage, current, and power and the total energy generation and use over time? These questions take us to step 3.</p>
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<p>Each step in the lesson purposefully ends with some questions to teach by example to students a way of teaching themselves. By noticing details that lead to questions and then by posing good question, the student can guide himself or herself to good answers. Proceed slowly to let the method sink in.</p>
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<center>
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<img src="edu4-3.gif" width="645" height="497" border="2" vspace="5" hspace="9">
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</center>
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Fig. 3. AC Power Curve
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</center>
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<h3>AC POWER AND WORK</h3>One of the difficulties I have encountered with most explanations of AC power is that the curve for that power over a complete generator cycle is rarely, if ever, shown. Fig. 3 at the top of this page rectifies the situation. Some experienced hams I have met never realized that the curve was symmetrical relative to its peaks and valleys. This curve can simplify the explanation of average AC power and its relevance to r.m.s. voltage and current.
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<p>The curve, of course, is simply a sine-squared curve with a maximum value of 1. If you have access to a spreadsheet program, you can produce full-page curves to assist students in working with the next set of ideas. My procedure began with setting up spreadsheet columns for every 5 degrees from 0 to 360 degrees. The next row converts them to radians. (Use @RAD(X) formula on column A and copy it for the remaining columns as a block.) The third row takes the sine of the angle (@sin(X)) (using the same do-it-once-and-block-copy procedure). Row four uses the formula "A3 * A3" (with block copy for the remainder) to produce the values for a sine- squared curve. Graphing the results produces an accurate curve, labeled to taste. The curves shown here are flattened to take less vertical space, but spreadsheet programs with excellent graphing ability (such as Quattro Pro 7.0 used here) will proved full 8.5" by 11" graphs with fine resolution.</p>
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<p>The curve is very useful. First, it shows the variations in instantaneous power over time. The student can now see that the actual energy generated and used will be a function of time as he or she imagines the curve repeated over and over through many cycles. The resistor is going to warm up and reach a pretty constant temperature with AC, just as it did with DC.</p>
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<p>Discovering how much energy is used per unit of time will require more than an instantaneous readout. It will require that we average the power of the cycle, meaning a time period of 360 degrees. Thinking of degrees as time units is important in the understanding of AC, and many students never catch on to this fundamental notion. If it helps, you can convert each degree (or five degrees) into a period of milliseconds. However, to keep the student from thinking these ideas apply only to American house current, use several AC frequencies in the power range. At 60 Hz, a cycle takes about 16.7 milliseconds or about 46 microseconds per degree. In Europe, where 50 Hz is fairly standard, a cycle takes 20 milliseconds at about 55 microseconds per degree. That is fast, but finite.</p>
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<p>Returning to Fig. 3, we can by visual inspection alone see that the 0.5 line represents the average of all the values on the curve. The student should draw a line across the page on this 0.5 dotted line to emphasize it. The area inside the peaks above the 0.5 line equals the area outside the peaks and below the 0.5 line: the missing power and the present power are the same. Cutting up a graph to show this can take any distrust out of the student's inspection. Of course, rudimentary integration techniques would confirm the visual findings, but we shall not presume of the student any math we cannot easily teach along the way.</p>
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<p>The result of this exercise is the convincing confirmation of the fact that the average power is half the peak power. Otherwise expressed.<br></p>
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<center>
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Pave = Ppk / 2 (8)
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</center><br>
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Therefore, if every cycle beyond this first one is the same, the total energy generated and used is a function of the average power multiplied by the time of generation and use.
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<h3>PDC AND PAVE</h3>The fourth step in our process takes us back to DC. Suppose we want to heat the resistor in both the DC and AC circuits to the same temperature, indicating an equivalent conversion of electrical energy into heat energy. In this case, the average energy use--and hence the average power--must be the same in both cases. For DC, this rate of use is a constant, the same at every instant. For AC, it is the average rate of use across at least a half cycle of many identical cycles. Otherwise expressed,<br>
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<center>
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Pave = Pdc (9)
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</center><br>
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Since, the average AC power is equal to the constant DC power, the peak AC power must be twice the DC power, or<br>
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<center>
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Ppk = 2 x Pdc (10)
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</center><br>
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<p>Before we leave Fig. 3 behind, let's take one more look at it. There are four points on the graph where the instantaneous AC power equals the average AC power. Those are the points where the graph of instantaneous power crosses the 0.5 horizontal line. Along the time or 0-to-360-degree axis, those points are 45, 135, 225, and 315 degrees. Looking back at Fig. 2, we can see that these points are the half-way points along the arc from 0 to 90 degrees, from 90 to 180 degrees, etc. Whether we look at the circular diagram or the power curve, we can conclude that the power is below the 45-degree point for half the time and above it for half the time.</p>
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<p>We now have a fairly clear picture of electrical energy doing work, whether that electrical energy is AC or DC. Doing the same work indicates an equivalence between the two forms of electrical energy.</p>
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<p>However, we still have a question or two left over. If the DC power equivalent of AC power is the average AC power or half the peak AC power, what will be the values of AC voltage and current relative to peak voltage and current that will be equivalent to their DC counterparts?</p>
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<h3>EDC-EQUIV AND IDC-EQUIV</h3>Our fifth step will be to find the voltage and current that produce the average AC power that is one-half the peak power. We have several routes by which to do this. The best effect on students occurs when we use all of them, for then we can show the interrelationship of numerous basic AC ideas. Here, we shall show only two.
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<p>1. Remembering that the peak power is 1 watt produced by a peak voltage of 1 volt and a peak current of 1 amp, we can ask what voltage and current are needed to produce a current equal to half the peak power. We are specifically looking for a voltage and current with the same numeric value. Other voltage and current values that produce the same power can be derived with a single constant, k, such that<br></p>
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<center>
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(k x E) x (1/k x I) = P (11)
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</center><br>
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<p>Therefore, Edc-equiv = Idc-equiv for the problem at hand. We are seeking a numeric value which, when multiplied by itself, produces the desired power value. This, of course, is simply the square root of the power value. However, some students may well have lost track of the concept of square roots and require an explanation of this order.</p>
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<p>The DC-equivalent voltage and current are both the square root of the average or dc-equivalent power. We might formalize this as<br></p>
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<center>
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Edc-equiv x Idc-equiv = 0.5 Ppk (12)
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</center><br>
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or<br>
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<center>
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Edc-equiv x Idc-equiv = 0.5 x (Epk x Ipk) (13)
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</center><br>
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To find a multiplier to apply equally to the peak voltage and to the peak current, we simply take the square root of 0.5, that is, we find a number which when multiplied by itself equals 0.5. The result can be pressed out of any calculator:<br>
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<center>
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Edc-equiv x Idc-equiv = 0.707 Epk x 0.707 Ipk (14)
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</center><br>
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or<br>
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<center>
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Edc-equiv = 0.707 Epk (15)
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</center><br>
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and<br>
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<center>
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Idc-equiv = 0.707 Ipk (16)
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</center>
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<p>Of course, from our discussion of the basic generator and resistor circuit, both the voltage and current may be negative, but only at the same time.</p>
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<center>
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<img src="edu4-4.gif" width="639" height="497" border="2" vspace="5" hspace="9">
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</center>
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<center>
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Fig. 4 Sine curve of circularly generated AC voltage or current.
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</center>
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<p>2. The graph of the instantaneous values of voltage and current form sine waves, as shown in Fig. 4. It is possible to compare this graph with Fig. 3 to derive some valuable data, but combining graphs can make the comparison easier. Fig. 5 combines the voltage-current sine wave with the graph of instantaneous values of power using separate axes, one on the left, the other on the right. Fig. 6 takes a different approach. If the student understands that a negative voltage times a negative current yields a positive power, then we can graph the absolute values of the voltage or current to produce the graph in Fig. 6. To graph absolute values on a spread sheet, simply add a new line in column A, using the @ABS(X) function. Then, block copy the new line in A for all columns from 0 to 360 degrees.</p>
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<center>
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<img src="edu4-5.gif" width="640" height="513" border="2" vspace="5" hspace="9">
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</center>
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<center>
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Fig. 5. Combined AC voltage/current and AC power graph with separate Y axes.
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</center>
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<center>
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<img src="edu4-6.gif" width="638" height="510" border="2" vspace="5" hspace="9">
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</center>
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<center>
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Fig. 6. Combined AC voltage/current and AC power graph using absolute E and I values.
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</center>
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<p>Whichever graphing system you use, call attention to the number of degrees at which the power crosses the 0.5 horizontal line. Then ask what the voltage and current are at these degree points. You can read approximate values from the graph at the 45, 135, 225, and 315 degree points: a little over 0.7.</p>
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<p>Taking the sine of any of these points produces a value of 0.707 for 45 and 135 degrees and -0.707 for 225 and 315 degrees. For a power of 0.5 Ppk, the resultant voltage and current are 0.707 Epk and 0.707 Ipk, respectively.</p>
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<p>Fig. 6 also demonstrates that except for the 0 and 1 points on the graph, both the voltage and the current must have values greater than the numerical value of the power (when voltage and current are equal, before multiplying one by k and the other by 1/k).</p>
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<p>Finally, the graph demonstrates that the value of voltage or current that is 0.707 times the peak value of each represents the same time division line as the 0.5 peak power point. That is, for half the time of each cycle, the value of voltage, current, or power is less than the indicated value and for half the time of each cycle, the value of voltage, current, or power is more than the indicated value.</p>
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<p>The graphic ideas dovetail with the straight arithmetic ideas perfectly. That is the goal of teaching the same lesson from more than one point of view. Some students learn best by seeing the calculations; others learn best from examining the graphs. Some will even combine ideas from the two perspectives before catching on. Do not rely on mere repetition.</p>
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<h3>REVERSING THE PROCEDURE</h3>Whichever route we use, the result is the same. We have established that the DC equivalents of AC voltage and current are 0.707 of the peak values of AC voltage and current. Now we let 1 AC voltdc-equiv = 1 volt DC and 1 AC ampdc-equiv = 1 amp DC. This procedure is proper since these values in both AC and DC circuits produce equal energy generation and use.
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||||
<p>What then is the value of the peak voltage and current relative to the DC equivalent values. Since 1 DC equivalent volt or amp = 0.707 the peak voltage or current, the peak voltage or current must equal the DC equivalent voltage or current divided by 0.707, or<br></p>
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<center>
|
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Epk = Edc-equiv / 0.707 (17)
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||||
</center><br>
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and<br>
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<center>
|
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Ipk = Idc-equiv / 0.707 (18)
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||||
</center>
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||||
<p>At this point, you can introduce the student to the magic of the square root of 2. 1 divided by 0.707 = 1.414 and vice versa. 0.707 equals half the square root of 2 or 1.414 / 2. If your students are interested, you may wish to return to the basic ideas of trigonometry and geometry to trace the use of the square root of 2 in connection with the sides and the hypotenuse of right triangles. Familiarity with these relationships will pay dividends to the student in his or her later study of electronics.</p>
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||||
<p>Or you may just give as a memory exercise the conventional formulas:<br></p>
|
||||
<center>
|
||||
Epk = Edc-equiv x 1.414 (19)
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||||
</center><br>
|
||||
and<br>
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||||
<center>
|
||||
Ipk = Idc-equiv x 1.414 (20)
|
||||
</center>
|
||||
<h3>RENAMING DC-EQUIVALENCE</h3>Let's return to Fig. 4, which so far has done very little work alone. Using the middle or "0.0" line as our referent, we can ask what the value is of all of the instantaneous values of voltage or current for either the top or bottom part of the curve. Since the voltage and current are constantly changing, each instant is infinitesimally small. We can sample the process by taking the values at each 5-degree interval, using a calculator with trig functions and an accumulating memory. (Using the first 90 degrees of the curve cuts the calculation to 19 data points. However, the trade-off is a slightly greater departure from the correctly derived value.) The result is about 0.629 of the peak value. The student is not stretched very far to learn that the average of all the instantaneous values is 0.637 of the peak value. This "average" AC voltage or current value, of course, is useful for understanding circuits where the alternating current has been rectified to provide pulses in only one direction.
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||||
<p>Let us try another method of "averaging." First, take the square of each instantaneous value. Next, add up all the squares. Third, take the average (or the mean) of all the squares by dividing the total of the squares by the number of instantaneous values. Finally, take the square root of the result.</p>
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<p>This "root mean square" (r.m.s.) method of taking the square root of the mean of the squares of all the values of the voltage or current under the curve, ranging from 0 to 1, yields a value identical to the DC equivalent value of voltage and current. We can approximate the process by checking all values at 5-degree intervals. The result, using 19 data points (like the result of using all possible instantaneous values), is 0.707 of the peak value. The full r.m.s. calculation simply expands our earlier arithmetic derivation of DC equivalent values.</p>
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||||
<p>From this fact, Edc-equiv and Idc-equiv get their common names: Erms and Irms, where "rms" means "root mean square." Hence, we may take the final step of relabeling earlier formulas:<br></p>
|
||||
<center>
|
||||
Erms = 0.707 x Epk (21)
|
||||
</center><br>
|
||||
<center>
|
||||
Irms = 0.707 x Ipk (22)
|
||||
</center><br>
|
||||
Conversely,<br>
|
||||
<center>
|
||||
Epk = 1.414 x Erms (23)
|
||||
</center><br>
|
||||
<center>
|
||||
Ipk = 1.414 x Irms (24)
|
||||
</center><br>
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Now the student has in his or her possession precisely the relationships required by the exams. In addition, he or she also has a grasp of the interrelationships of many of the fundamental ideas relating to AC and DC voltage, current, and power. In the long haul, the latter understanding is more important.
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<p>The process of thoroughly teaching r.m.s. values of AC requires patience. It may not be for every new amateur student. It requires helpful analogies and lots of teacher personality. But, when a student really catches on, the effect is rewarding to teacher and student alike.</p>
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<p><i>From</i> Proceedings of the 1995 National ARRL Education Workshop<i>, (Newington: ARRL, 1995), pp. 33-40 © L. B. Cebik, W4RNL. Data may be used for personal purposes, but may not be reproduced for publication in print or any other medium without permission of the author.</i></p>
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<title>Antenna Modeling Programs as Teaching Tools</title>
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<h1><img src="../images/edu.gif" align="left" width="100" height="83" border="2" vspace="5" hspace="9"> <img src="../images/w4rnlwwr.gif" align="right" width="99" height="83" border="2" vspace="5" hspace="9"> Antenna Modeling Programs as Teaching Tools</h1>
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<h3>L. B. Cebik, W4RNL</h3>
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Among all the new phenomena to which we introduce new ham students, antennas may leave them least comfortable. Even experienced hams have trouble understanding this deceptively simple transducer that converts electrical energy at radio frequencies into electromagnetic radiation. The sample whips, dipoles, and VHF Yagis we bring to class may not help. I can hear the facial expressions: they say, "That bunch of wire does WHAT?"
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<p>At the Novice and Tech level, antenna questions are few, but cover a surprisingly sophisticated array of concepts. Most students have little choice other than to commit correct answers to memory. Those who want to know more, however, can fix in mind a number of important ideas abetted with a well-guided tour of one of the numerous antenna modeling programs now available.</p>
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<h3>Some Advantages</h3>For those uninitiated to antenna modeling programs, here is a very cursory description. Both MININEC and NEC-2 use different implementations of a mathematical technique called the method of moments to model the performance of antennas. The user constructs an antenna model by specifying its element dimensions and height. The program provides a sketch of the modeled antenna and pictures of the resulting radiation pattern (the far field), along with data about electrical conditions at the antenna feedpoint and along the elements. This is not all the programs do, but it is enough for basic instruction. Likewise, each program has limitations, but none will be pressed in the course of basic antenna instruction.
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<p>Here are some advantages of using an antenna modeling program:</p>
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<p>1. <b>Economic availability</b>: Antenna modeling programs are available at a very reasonable cost, given their long term benefits. Of course, the program owner can also use it to good purpose outside the classroom. At this level, it does not matter whether the teacher chooses a version of MININEC or of NEC-2: both are more than adequate to the task of vividly guiding students through some basic ideas.</p>
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<p>Programs useful for teaching are available from many sources. EZNEC (NEC-2), available from Roy Lewallen, W7EL and NEC-Win Basic (NEC-2) from Nittany-Scientific, Inc. are but 2 of numerous NEC programs. Terisoft produces Antenna Model, a MININEC program. Program prices range from about $50 to $150, a bargain for what you get.</p>
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<p>2. <b>Dynamic instruction</b>: Antenna modeling programs are dynamic. Basic concepts can be taught statically, using chalkboard, models, and various graphics. However, antenna modeling programs permit the instructor to guide the student through some basic comparisons, overlaying one pattern on another. They also permit real variation of antenna variables, such as dipole length, to connect real wire dimensions to real consequences. Students can ask questions about variations on an instructional model and watch their variations yield results.</p>
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<p>3. <b>Small group instruction</b>: The programs, being PC-based, encourage small group instruction. Four or five students gathered around the instructor create a good learning environment. When numbers are small, students tend to ask more questions than they do in large classes. They feel freer to offer comments that reveal how well they do or do not understand the ideas involved. Responses can be tailored to individual needs. Of course, the instructor may need to repeat the procedure in order to serve everyone in class, but he or she will discover that no two sessions are alike, a pleasing challenge for most teachers.</p>
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<p>4. <b>Scripting</b>: Antenna modeling programs permit careful scripting of the guided tour. All programs permit the user to save each antenna model as a separate small file. The instructor can organize a progression of files by names or numbers. In class he or she can then keep track of what comes next with a simple list of topics and filenames.</p>
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<p>Of course, it also pays to have on hand a number of supplementary models designed to anticipate probable student questions. Constructing a good model of even such a basic antenna as a 2-meter quarter-wave vertical with a sloping set of ground plane radials can take a good bit of time. Preplanning keeps the class running smoothly. However, every class will likely add new models to the list of supplements.</p>
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<p>Even experienced lesson plan writers who organize teaching material by expert second nature should not expect to purchase a program and instantly use it in the classroom. Antenna modeling programs need to be mastered carefully. They contain numerous variables that surround the situation of an antenna, and the user must learn how to set them and the best values to use. Modeling the antenna itself requires mastery of the program's key words, such as "wire," "segment," "source," and "load," and what each means to a good antenna model. If using a three axis coordinate system (X, Y, Z) for antenna dimensions is unfamiliar, it will require practice to handle smoothly. If elevation and azimuth patterns are not second nature, they will require some study so that the instructor can select the relevant patterns and speak about them usefully.</p>
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<p>All of these (and other) preparation steps take a bit of time. Fortunately, the manuals that accompany antenna modeling programs are quite detailed and thorough. Additionally, all of the listed programs provide the user with pre-modeled antennas to familiarize him or her with modeling conventions and practices. For a bit of initial guidance, you might look at the following item: "A Beginner's Guide to Using Computer Antenna Modelling Programs," <i>The Antenna Compendium</i>, Vol. 3 (Newington: ARRL, 1992), pp. 148-155; reprinted in <i>Vertical Antenna Classics</i>, ed. R. Schetgen (Newington: ARRL, 1995), pp. 10-17.</p>
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<h3>Some Basic Modeling Exercises</h3>Before introducing students to anything a modeling program might do, be certain they are familiar with some basic concepts. Among them are "element," "vertical antenna," "horizontal antenna," "Yagi," and "SWR." They do not have to have a highly technical knowledge of the last two ideas, so long as they understand that a Yagi antenna has multiple elements, feeds only one of them, and is directional. They should also understand that SWR (VSWR) is an indication of the degree to which the antenna and the feedline are well matched, with a 1:1 reading indicating as good a match as can ever be obtained.
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<p>Bring some model antennas to the session, including a ground plane vertical, a dipole, a 2-element Yagi, and a 3-element Yagi. You can make miniature models from wire, wood dowels, and the like. Their purpose is both visual identification and orientation to what the antenna modeling patterns show.</p>
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<p>Using the miniature models, orient the students to the ideas of elevation pattern and azimuth pattern by having them look down the ends of the horizontal antennas and then from above. You will also need the miniatures later to demonstrate what it means to look at an azimuth pattern at an angle above horizontal and to look at patterns of antennas that are vertically and horizontally polarized.</p>
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<p>For these exercises, it is likely best to keep all models over real ground rather than trying to explain the difference between free space and real ground. Students will be more intuitively familiar with antennas a certain height above ground.</p>
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<p>1. <b>80-Meter Dipole</b>: A #14 wire dipole for 3.7 MHz about 50' above real ground makes a good starting exercise. You can begin by showing them the model file with the wires (about 62.3' each side of center). Since the angle of highest radiation for this low dipole (relative to a wavelength at 80 meters) is straight up, preset the azimuth pattern angle at about 45 degrees Make this model as resonant as you can, hopefully with a feedpoint reactance under 1 Ohm.</p>
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Fig. 1. The elevation pattern of a typical 80-meter wire dipole 50' above ground. Note that maximum radiation is nearly straight upward.
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<p>There are three major items this model can illustrate. a. By showing students the elevation pattern, you can explain what a pattern shows, namely, that at some distant points (but not skip distance), the signal strength would be the same at each point along the perimeter of the pattern. This is a measure of the strength of the radiated field in the transmit mode and the sensitivity of the antenna to received signals. You can also explain that because the antenna is so low in height compared to the length of a wave (80 meters long), much of its energy is radiated straight upward, but with plenty going off at angles for good ham communications.</p>
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fig. 2. The azimuth pattern, at 45 degrees above horizontal, for the same dipole antenna. The antenna wire runs left to right at the pattern center.
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<p>b. Next you can show them the azimuth pattern at 45 degrees upward. Not only will this verify that there is good energy for communications, but as well, it will show that the classic figure-8 pattern of a dipole applies only to antennas with greater height relative to a wavelength.</p>
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<p>c. Show the students the feedpoint conditions report, including the feedpoint impedance and the SWR. Even though the books place the resonance impedance of a straight dipole at 70-72 Ohms, our low antenna shows an impedance of 57-58 Ohms resistive. Now note the good match to standard 50-Ohm coax with an SWR of about 1.15:1.</p>
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<p>This is a good opportunity to introduce the student to how to refine his or her own antenna. Construct a second version of this model lengthened so that it shows about a 2:1 SWR at 3.7 MHz. 64.9' each side of center should do the trick. Construct a third model of the antenna shortened to achieve the same 2:1 SWR; 62.3' will be quite close. Again, sow the student each model and the feedpoint report, noting the inductive (+) reactance for the long model and the capacitive (-) reactance for the short one.</p>
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<p>If the student has only an SWR meter to make measurements, he or she cannot initially tell from a 2:1 SWR that the antenna is too long or to short. Typical advice to new antenna builders includes finding the lowest SWR point for the antenna. You can use the long and short models to make this point more real to students. The short antenna will show resonance (less than 1ê reactance) at about 3.775 MHz, while the long antenna will resonate at about 3.625 MHz. Obviously, we lengthen the short one and prune the long one, but not to the model dimensions. Instead, we strive with simple antennas for lowest SWR at or near the frequency we want to call the design center.</p>
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<p>One final note: you can also compare the gain numbers. It is not important whether you use dBi or dBd. Here, it is important for the student to note that the SWR figures do not significantly change the gain of the antenna at all. Make sure they do not get caught up in any numbers past the first two digits, even though programs often give more decimal places. And be sure they understand that a difference of one decimal place is operationally meaningless.</p>
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<p>2. <b>Dipoles and Yagis</b>: Because the programs permit you to save and then overlay various patterns developed by the numerical analysis, it becomes convenient to demonstrate to students the basic principles of gain. Perhaps 10 meters is the best place to perform this comparison, since this is a band for both dipoles and Yagis.</p>
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<p>Start by bring on screen the pattern of a typical dipole, a little over 16' long. Use the azimuth pattern at the proper take-off angle. If you place the dipole about 30-35' up in the air over real ground, students can see that, compared to the 80-meter dipole, the classic figure-8 pattern is reappearing because the antenna is now closer to a full wavelength up in the air.</p>
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Fig. 3. comparative azimuth patterns for a 10-meter dipole, a 2-element Yagi, and a 3-element Yagi, each 35' above ground. All patterns were taken at an angle of 14 degrees above the horizontal. Most programs will have on-screen indicators of which pattern belongs to which antenna.
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<p>Now call up the pattern of a 2-element Yagi that you have previously saved and let it overlay the dipole pattern. Having a miniature physical model on hand and orienting it in the same plane as the miniature dipole will let you bypass any steps needed to show the antenna on screen and thus let you go straight to the azimuth pattern. Again, use the same antenna height above ground and the proper take-off angle.</p>
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<p>You are now in a position to show students the modest, but real gain of the Yagi over a dipole, as well as demonstrating the basic idea of front-to-back ratio as an aid in reducing QRM. Teach them also to scan the entire rear lobe of the antenna to note its shape and the relative QRM reduction from all rear quadrants (what some call the front-to-rear ratio). When counting the grid layout rings, labeled in dB, remember that a full S- unit on the student's receiver will be about 6 dB.</p>
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<p>If your program permits, add a third pattern from your saved files, this time for a 3-element Yagi. Again, use a physical miniature to orient the students to the antenna. Students should instantly note the further, but small increase in gain. However, they should also note the more significant increase in Front-to-back ratio and the improvement in the overall front-to-rear ratio. Well designed Yagis, and their models, should show another S-unit of improvement in rear rejection.</p>
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<p>You should also stress that the humble dipole begins with good gain over real ground. For all the advertising claims and impression left by the claims, the dipole remains a good antenna for making excellent contacts across the country and world. Directional antennas like the Yagi are helpful in many ways, but they are not absolutely necessary for enjoying amateur radio.</p>
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Fig. 4. Elevation patterns of the same antennas as in Fig. 3.
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<p>Unless students have specific questions about the feedpoint conditions, you should avoid burdening them with the numbers associated with the Yagis. The lower numbers require that one use a matching system, an advanced topic. If the student buys a beam, the manufacturer will explain the tune-up procedure for that system. Is a student wants to build a beam, you can give that individual a little one-on-one instruction on the side.</p>
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<p>3. <b>A 40-15 Dipole</b>: A misconception many students pick up is that if they use a dipole, it must have something like the figure-8 pattern. A little exercise with a 40-meter dipole can correct that impression very quickly. The first step is to construct a model of a 40-meter dipole, perhaps 50' high. Make it a little long, perhaps 68.8' long with #14 copper wire. At 7.1 MHz, show the azimuth pattern at about 39 degrees take-off angle. The very oval shaped 80-meter dipole pattern for an antenna at the same height in feet is now just beginning to pinch in its sides, since the antenna is twice as high relative to a full wavelength at its frequency.</p>
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Fig. 5. Azimuth patterns of a 40-meter dipole used at 7.1 MHz and at 21.2 MHz.
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<p>Next, simply change the frequency to about 21.2 MHz, on the pretext of showing them that a 40-meter dipole can be used at 15 MHz also. Let the 6- petal pattern emerge. You can then explain that an antenna's pattern depends in part on how long the antenna is relative to the length of a radio wave. If they prefer the figure-8 pattern, they will have to construct a half-wave dipole specifically for 15 meters. If they are interested, you might use the miniature antennas to add some practical notes on orienting the antenna so that maximum radiation goes in the most desirable directions. In my part of the country (TN), running the wire North-South gives good 40-meter coverage East and West, while placing the strongest 15-meter lobes on some of the best DX paths.</p>
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<p>These simple active exercises have introduced students to concepts they need to understand to pass the license test. In addition, they have enabled some very practical instruction on the side. That aspect of the instruction makes the test questions far more meaningful to the student. Once you start the process of developing models for class, you will discover many more useful workouts with models.</p>
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<h3>Some VHF Exercises</h3>VHF is a good place to introduce vertical antennas to the student, since repeater operations are virtually all vertically polarized. In your collection of miniature antennas should be a quarter-wave vertical with ground plane, a 5/8ths wavelength vertical with ground plane, and perhaps a 3-element Yagi that you can orient both horizontally and vertically. Of course, at 2 meters, you can bring in full-size antennas to assist the learning process.
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<p>4. <b>Quarter-wave and 5/8ths-wave Verticals</b>: Although handheld 2-meter rigs use rubber duck antennas, the student may wish to use an outdoor antenna at home. Some version of a ground-plane vertical will likely be the first choice, perhaps atop a 25' roof peak. It is fairly easy to model a 146 MHz version of such an antenna with 4 radials. Make the radials about 20.2" long each on a flat plane and the radiator about 20.05" straight up, all using #12 copper wire. This is a ground plane the student can actually build.</p>
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<p>First show the students an azimuth pattern (take-off angle about 3ø) to confirm that they understand that vertical antennas provide a uniform pattern of radiation in all directions (unless interrupted by nearby objects). Then switch to an elevation pattern. The elevated vertical antenna provides a certain signal strength in its lowest lobe. Just for reference, have the students record the gain figure for the antenna (about 5.4 dBi or 3.3 dBd).</p>
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<p>Also call attention to the complex pattern of upper lobes. Caused by interactions between the basic (incident) radiation of the vertical and reflections from the ground plane, these lobes are hardly ever useful at VHF for repeater work. Finally, call attention to the feedpoint report, noting the low feedpoint impedance and SWR (a little greater than 2:1). Have students record this with the gain number.</p>
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<p>Next, start a new model, this time a 5/8ths wavelength vertical. Using the same ground plane, simply extend the length of the vertical element to about 45 inches. Go through the same steps, first verifying the uniform azimuth pattern and then showing an elevation pattern. Students have heard that 5/8th wavelength antennas are supposed to have a theoretical gain over a quarter-wave vertical of about 3 dB. Hence, they may be surprised to learn that with such a simple ground plane, they are unlikely to achieve more than something over a half dB of gain.</p>
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<p>Finally, show them the feedpoint condition report. If they have wondered why 5/8th wavelength antennas have a little tapped coil at the base, they can at least partially understand why. The base coil is a matching circuit to permit the use of 50-Ohm coax with the complex impedance of the longer antenna.</p>
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<p>As a final exercise in the series, return to a quarter-wave vertical with its 4 ground plane radials, all of #12 copper wire 25' high. In the model, bend the radials down 45 degrees. You can use the Pythagorean theorem to calculate the outer end coordinates (about 14.3" out and the same down). The shift in ground plane position will require that you shorten the vertical whip to about 18.67" long. This should resonate close to 146 MHz.</p>
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<p>You may wish to start the run of this model with the feedpoint conditions report. Compare the results with the flat ground plane model. The sloping ground plane yields a very good match for 50-ohm coax--so close that any difference does not make a difference. If a home-made antenna is not a perfect match, the student can always add more or take away from the bend of the radials to perfect the match.</p>
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Fig. 6. The elevation pattern of a 2-meter ground-plane vertical antenna at 25' above ground. The shape of the pattern applies to all three antennas discussed in the text, with only small differences in the gain of the lowest lobe.
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<p>If students trust by now that the vertical radiates uniformly in all horizontal directions, go straight to an elevation pattern. While all three elevation patterns have similar features, including the complex array of high lobes, this pattern shows a bit more gain than the flat plane quarter-wave vertical and perhaps an insignificant amount more than the model of the 5/8ths wavelength vertical.</p>
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<p>If you wish the students to think about this situation, you might ask them how we could get more gain when we actually shortened the vertical whip by a tiny bit. The answer, of course, lies in the sloping ground plane elements. Now they operate not only as a ground plane, but as an approximation of a vertically oriented dipole. That is, the ground plane elements add to the radiation of the antenna. Hence, more power is radiated than with the flat plane quarter-wave vertical, whose ground plane added virtually nothing to the power radiated.</p>
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<p>If any of these antennas is well matched to the feedline, it will perform quite well for the student. The gain differences are too small to make a practical difference. More significant differences emerge from changing the height of these antennas. At 6' off the ground, they all perform comparably to each other, but all at reduced gains, reductions that may make a difference in practical operations.</p>
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Fig. 7. Elevation pattern of the same ground-plane vertical antenna at a height of 6' above ground.
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<p>If you run this supplemental exercise, you will note that the 5/8ths wavelength vertical provides somewhat more gain than either of the other two models (but still under 1 dB). That little extra may account for the popularity of the 5/8ths wavelength antenna as a mobile antenna.</p>
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<p>2. <b>Horizontal and Vertical Yagis</b>: Many students will be tempted early after receiving their licenses to put up a small beam for extended repeater coverage. From advertisements, they are perhaps used to seeing the azimuth patterns of horizontally polarized Yagis. However, they may be surprised by the azimuth pattern of a vertically polarized Yagi.</p>
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<p>First, model a small, 3-element 2-meter Yagi. These dimensions, set for 146 MHz, may be useful to you:</p>
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||||
<pre> Reflector length: 39.8"
|
||||
Space: 18"
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||||
Driven Element length: 37.25"
|
||||
Space: 14.5"
|
||||
Director length: 33.4"</pre>
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<p>This compact beam has a front-to-back ratio around 20 dB, and its 40-Ohm feedpoint impedance matches well to short runs of coax. With half-inch diameter aluminum elements, it is a distinct candidate for homebrewing.</p>
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<p>Construct the model for this beam in the horizontal plane. Bring up the azimuth pattern (4 degree take-off angle at a 25' height). From the HF exercises, students will recognize the typical Yagi pattern.</p>
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||||
<p>Next construct in advance the same beam oriented vertically. In class, simply overlay the pattern of the same beam at the same height (measured at the boom) in its new orientation. Now explain the "eyeball" pattern.</p>
|
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<p>Miniatures are useful in helping students grasp why the pattern spreads, with slightly less gain. Horizontally, ground reflections strengthen the lowest lobe and create some high lobes (visible on an elevation pattern). The beamwidth is a function of the antenna's geometry of tapering element lengths. Vertically, the radiation that bounced off the ground in the horizontal mode now can spread to its fullest extent, for a beamwidth almost double the horizontal orientation. Only the weaker side (element end) radiation now reflects off the ground; hence, slightly less gain.</p>
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Fig. 8. Azimuth patterns of the same 3-element 2-meter Yagi oriented horizontally and vertically at a height of 25' above ground.
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<p>Operationally, these facts mean that a Yagi set up vertically for repeater and other FM work need not be moved as often to catch stations slightly off the beam's axis. Although the wider beamwidth of the vertical orientation may occasionally permit some QRM, the ease of finding a heading that permits full quieting operation on FM will usually outweigh the uncommon irritation.</p>
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<p>Students are likely to notice that the beam offers very significant gain over a vertical. You should therefore remind them of the other costs involved in putting up a beam, including the need for a rotator. Get them from the start to think about how an antenna relates to the kind of operating they envision doing, and how the entire communications system fits into a budget. The models of beams may not only explain some basic concepts to students, but may also attract them. Part of the lesson should be to help the student put everything in perspective.</p>
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<p>These sample exercises only scratch the surface of uses to which you may put an antenna modeling program in the classroom. I have purposely kept the samples close to the basic concepts students should master for the Novice and Tech licenses, along with some practical material so that they can have realistic expectations from their new stations.</p>
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<p>However, there are many features of these programs which you may use to good advantage according to your plans and style of teaching. Most programs provide rotatable views of the antenna model for comparison with miniatures or full-size VHF antennas. Some programs provide 3-dimensional views of the far field radiation patterns as a webbing: use these with caution, since they can both clarify and confuse. In the program reporting systems, there lies a wealth of data, most of which is best saved for more advanced students.</p>
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<p>Finally, there is the program itself. Some students will not be satisfied merely watching the demonstrations. They will want to learn how to use the program to understand other types of antennas and possibly one day to design their own. You may find yourself staying after class to teach a new generation of antenna modelers.</p>
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<p>Also see the <a href="../model/nec.html">Antenna Modeling Programs</a> page for more information.</p>
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<p><i>From</i> Proceedings of the 1996 National ARRL Education Workshop<i>, (Newington: ARRL, 1996), pp. 28-35 © L. B. Cebik, W4RNL. Data may be used for personal purposes, but may not be reproduced for publication in print or any other medium without permission of the author.</i></p>
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<a href="edu.html"><img src="../images/return.gif" align="bottom" width="40" height="40"> Go to Educational Notes Index</a><br>
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<a href="../radio.html"><img src="../images/rtnhome.gif" align="bottom" width="40" height="40"> Return to Amateur Radio Page</a><br>
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<p class="topics-footer">Topics: <a href='../topics.html#education'>Education</a>, <a href='../topics.html#modeling'>Modeling</a></p><br>
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<title>Introducing the "All-Band" Doublet</title>
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<h1><img src="../images/edu.gif" align="left" width="100" height="83" border="2" vspace="5" hspace="9"> <img src="../images/w4rnlwwr.gif" align="right" width="99" height="83" border="2" vspace="5" hspace="9"> Introducing the "All-Band" Doublet:<br>
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What the Student and the Instructor Should Keep in Mind</h1>
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<h3>L. B. Cebik, W4RNL</h3>
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<p>Perhaps too many new hams embarking on their first HF adventures think only of resonant dipoles fed with coaxial cable and plugged directly into the transceiver's output connector. Many end up with a mass of wires in the back yard as they try to make separate antennas for 80, 40, 15, and 10 meters. Others think that they are restricted to only one band because they have room for only one antenna. Too few modern Elmers have the personal experience to guide new HFers into one of the oldest ham antennas of all: the all-band doublet.</p>
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<p>It may be useful to review what it takes to get the doublet on the air effectively. The data comes in two parts: 1. information that every doublet user should have initially, whether a student or an experienced ham, and 2. opportunities for the instructor to assist students and new hams in gaining some practical knowledge about problem solving, parts acquisition, and a number of other areas that stop some newcomer projects in their tracks. An all-band doublet is a rather refined antenna system when looked at in detail, but it is also relatively easy to get on the air with it. If the student runs into difficulties or has questions, the instructor can help him or her work out the answers. There are many opportunities for advanced Elmering with the all-band doublet</p>
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<h3>The Basic Doublet Antenna System</h3>
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<p>As shown in Figure 1, the basic all-band doublet antenna system consists of 3 parts: the antenna proper, the feedline, and the antenna tuning unit (or transmatch).</p>
|
||||
<p>1. <b>The Antenna</b>: The antenna proper consists of a length of copper or copperweld wire, with a center feedpoint. Three popular lengths for the antenna are these:</p>
|
||||
<p>a. 130-140' (best, if you have the room and want the strongest results on 80 meters.</p>
|
||||
<p>b. 90-110' (works second best on 80 meters, with good results on all other bands).</p>
|
||||
<p>c. 65-75' (good for 40 meters through 10 meters, but not for 80).</p>
|
||||
<p>Notice that the precise length is not critical. Much more critical is getting the doublet as high as you possibly can. Although the antenna will work at low heights in the 20-25' range, it does much better (especially on 80 and 40) when it is higher than 35' up. You can use available trees for support, or you can even build your own support poles or trusses from designs in the ARRL Antenna Book.</p>
|
||||
<p>Many inexperienced hams will need guidance in the selection of materials. Obviously, #14 stranded wire, readily available at stores like Radio Shack, will fill the bill. However, if there is a local hamfest, you may want to guide the new ham in the purchase of copperweld wire. You may also have to guide him or her in its peculiarities, especially how to keep it straight while trying to assemble the antenna. Insulated copper wire will also work well if it is sufficiently strong. The inner ends will require insulation stripping to make connections, but the far ends may be left insulated. The twisting of wires at these ends to make a loop for the support line will introduce no significant changes to the antenna's operation.</p>
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<p>A second area where guidance can be critical is in the selection and use of antenna supports. Home-made trusses and their guying are not simple matters. Neither is trying to get a line over a branch 40' or more up a tree. The many techniques for launching a line often depend on local talent, whether that talent is tree climbing, bow-and- arrow, fishing rod, or slingshot. Guide the new ham to the local talent and be sure that safety lessons accompany the talent.</p>
|
||||
<p>Of course, the ends of the wire need to be insulated from the support, so you will need end insulators and rope for the job. A good 1/4" sun (UV)-resistant synthetic fiber rope will hold up most antennas unless they are stressed too tightly.</p>
|
||||
<p>Suppose that the antenna will not quite fit the space available. One standard technique of reducing the real estate needed is to set up the doublet in the inverted-Vee configuration. This version of the doublet tends to circularize the pattern, but reduce overall gain of the antenna at almost every frequency of use.</p>
|
||||
<p>Consider bending the elements instead (if supports are available). Drooping ends are the most common version of this arrangement. However, setting up the antenna as a "Z," with all parts of the antenna wire as high as possible, often provides better performance. Drooping ends, and even ends bent in the same direction, provides some radiation cancellation, especially on the lowest bands of use, while the zig-zag version--if not too radically Z-ed--tends only to bend the pattern's directions.</p>
|
||||
<p>Once more, a newcomer may need some guidance--or even just a second pair of eyes--to see clearly all the possibilities and potential problems of laying out an antenna within the confines of his or her yard. What makes a good support, what directions the wires should go for maximum communications, and what hazards to avoid are all questions calling for experienced advice. However, try not to take over the entire job from the newcomer.</p>
|
||||
<p>2. <b>The Feedline</b>: The second element is the feedline. For this antenna, we use a parallel transmission line because it has very low losses, no matter what the SWR (within reasonable limits). 300-Ohm TV ribbon line will work, but it is not the strongest. Most ham dealers can get 400-Ohm or 450-Ohm vinyl-coated transmission line with larger wires. Completely open ladder line, with only insulated spaces, also works well but is less common.</p>
|
||||
<p>Guidance in the selection of feedline may also be needed, especially in knowing which cheap and weak lines to avoid. If there is a local hamfest that is likely to draw a reputable antenna wire and feedline dealer, helping the new ham make his or her purchases is an act likely to be appreciated for years to come.</p>
|
||||
<p>Unlike coaxial cable, which you may run close to any object, parallel transmission line should be as free and clear of objects as possible. If the line must be brought down parallel to an object, such as the wall of a house, use insulated spacers to keep the line several inches away from the object. Avoid bringing the line near metal gutters and down spouts, power lines, conduits, or other metallic objects. Close proximity to metal can disrupt the balance between the wires of the feedline, adversely affecting its performance. Wherever the line must change directions, keep the angles shallow and, if at all possible, keep the line at right angles to the antenna wire.</p>
|
||||
<p>Use special care when attaching the feedline to each side of the antenna wire center feedpoint insulator. Be sure that connections are mechanically secure, and then solder the feedline wires to the antenna wires. Test the connections for movable wire bends that may cause a break while swaying in the wind. Recently, some ladder-line "grabber" center fixtures have appeared on the market to secure the ladder line to the antenna wire and reduce the danger of breakage: they are well worth the investment.</p>
|
||||
<p>One special problem deserves special attention: getting parallel feedline into the shack and over to the antenna tuner. There are almost as many ways to solve this problem as there are all-band doublet installations. The type of solution used depends largely on where the feedline enters the house.</p>
|
||||
<p>If the feedline enters at a window, one can bring it through the window frame or through a board installed at the base of the window. Both have advantages and disadvantages. Bringing the line though the wooden window frame defaces the frame. Using a board on which the bottom section of the window closes requires special means to ensure insulation and security around the window. In each case, one can use a pair of bolts spaced about the same distance apart as the wires and make separate indoor and outdoor attachments. This feature is important, since it permits detachment of the feedline when electrical storms are imminent or when going on vacation.</p>
|
||||
<p>Feeding a parallel transmission line through a wall calls for even greater care. One simple system (among many) uses a short length of PVC run through the wall and weather sealed around the edges. Some hams center the transmission line in the tube and hold it in place with fiberglass insulation. Others use plastic spacers with a center cutout to hold the line in place and seal the tube. There are many variations on this theme, but the old idea of simply slamming a window frame down on the transmission line at the window should be discouraged, especially with metal window frames. In all cases, there should be a way of disconnecting the transmission line out of doors and grounding it.</p>
|
||||
<p>Routing the feedline within the house or shack calls for equal care. Ideally, the tuner should be as close to the line exit point as possible. Feedline should not be simply drooped on the floor or haphazardly tacked to the walls and ceiling. Spacing from invisible metal in the wall cavities is as essential indoors as is spacing from outdoor metallic objects.</p>
|
||||
<p>Helping new hams analyze where duct work, house wiring, telephone wires, and metal plumbing pipes may be located in house walls is another arena of assistance too often overlooked. Many new hams are as initially uneducated about house structures and utilities as they are about amateur electronics. Showing the student how to look at house fixtures, outlets, switches, telephone and cable connections, and plumbing routes and to use these signs to make good estimates of their routings through the house may be a really enlightening experience for the student.</p>
|
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<p>3. <b>The Antenna Tuning Unit or Transmatch</b>: The "antenna tuner" is a network for transforming the impedance that is present at the shack end of the transmission line to another value, normally 50 ohms. An all- band doublet shows a different feedpoint impedance at each frequency of operation. The exact length of the antenna relative to the frequency will largely determine that impedance. The feedline will transform that impedance continuously along its length, repeating values every half wavelength of line. Since most transmission lines have a velocity factor, a half wavelength of line will be shorter than a true half- wavelength for the frequency of interest.</p>
|
||||
<p>All of this together means that the exact impedance presented to the antenna tuner will vary from band to band and from one antenna installation to another.</p>
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<img src="edu6-2.gif" width="650" height="511" border="2" vspace="5" hspace="9">
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</center>
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<p>Most antenna tuners use unbalanced networks. The most popular network used in commercial tuners is the series C, parallel L Tee network, schematically shown in Figure 2. The popularity of this network stems largely from the fact that it is the most economical to produce and from the relative ease of tuning it to an adequate low-SWR match.</p>
|
||||
<p>Unbalanced networks employ a 4:1 transformer or balun to allow for the use of balanced feedlines. This feature often means that the antenna tuner settings that produce a low SWR between the tuner and the transceiver may not give the highest efficiency of power transfer. However, for most general purpose communications, efficiency will be adequate.</p>
|
||||
<p>Building one's own antenna tuner or transmatch is a good introduction into the satisfactions of home construction. Students may need guidance in the selection of parts, many of which are available these days only from surplus outlets or at hamfests. Helping the student select parts that are suitable in their range of values and their power-handling ratings without paying too much is an invaluable service. Another avenue of help is asking local club members to search their junk boxes for components they may be willing to sell or donate to the cause of aiding a new ham.</p>
|
||||
<p>A second avenue of guidance is helping the new ham select a suitable commercial tuner, if that is his or her favored route. Interpreting specifications, evaluating features, and teaching the student to look at the tuner as a long-term investment that can be useful many years down the road are all important activities that teach by example the practiced art of reading ads and brochures and making the best possible choice of equipment for one's present and future needs.</p>
|
||||
<p>Since antenna tuners do not wear out unless severely abused, used transmatches should be as good as new ones, and perhaps less expensive. Once more, helping a new ham scour a hamfest for the best used equipment available--showing him or her what to look for and what to look out for--may be a real service that has long-term benefits. New hams also need a little help in learning how to bargain down a price.</p>
|
||||
<p>If the all-band doublet is to be a long-term antenna for the new ham, and if home-brewing is an interest, then the best antenna tuner may not be the C-L-C network with a balun to handle balanced lines. Instead, there are circuits in the ARRL Antenna Book and elsewhere for link-coupled antenna tuners that have balanced outputs ready for the parallel feedline. Finding the right coil stock and capacitors, however, may be a fair-sized challenge these days.</p>
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<h3>Adjusting the All-Band Doublet</h3>Using the all-band doublet requires just a little more work than using a resonant dipole. The first job is to find the correct antenna tuner settings for each band you plan to use. However, once you have established these settings, you can make a chart and return to the settings, with only a moment's tweaking to set up the antenna perfectly.
|
||||
<p>Since the most common tuner is the C-L-C Tee with a balun for balanced transmission lines, let's see what the set-up for it consists of. First, use a low power setting for initial tune-up. Second, for each band, find an empty place to do your tuning in order to minimize QRM. Third, read the tuner manual to see if there are any recommended initial settings for the controls.</p>
|
||||
<p>The next step is to apply low power and find the settings of the controls that allow you to achieve a 1:1 SWR. Record the setting. Now increase power to the level at which you intend to operate. You may have to tweak the settings just a bit.</p>
|
||||
<p>Repeat the process for each of the bands. If you have never used this kind of set-up before, you might practice moving from band to band so that you do not forget to check the settings and make final adjustments before going to full power.</p>
|
||||
<p>For each band, also check how far up and down the band you can move the transmitter frequency without exceeding a 2:1 SWR. Make notes on whether the settings are broad or sharp for each band. Sharp tuning often indicates either of a high SWR or a high level of reactance at the tuner antenna terminals--or both.</p>
|
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<p>On some bands, you may find more than one set of control settings that will give a 1:1 SWR. For C-L-C tuners, the rule of thumb is to use the setting with the higher output capacitance, which usually coincides with a lower value of inductance. These settings are normally higher in efficiency. However, you should listen to signals on the band with each set of control positions and use the ones that yield the stronger signals--if any difference can be detected.</p>
|
||||
<p>At the other extreme, you may discover that on some bands, there are no settings that will produce a 1:1 SWR. This condition normally means that the impedance at the antenna terminals of the tuner has too much reactance, either capacitive or inductive, and the tuner cannot both compensate for it and also end up with a correct value to make the match perfect.</p>
|
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<p>The easiest method of overcoming this problem is to change the feedline length by patching in a 6' to 10' section of line between the tuner terminals and the "regular" line. Since a transmission line is an impedance transformer along which the values of resistance and reactance are constantly changing (if the SWR is initially greater than 1:1), changing the length of the line changes the values of resistance and reactance presented to the tuner.</p>
|
||||
<p>Sometimes, the new line length will work with all bands. In other cases, keeping the "patch-in" section handy is necessary for a few bands.</p>
|
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<p>For new hams, these procedures are often mysterious, and a "doom-and-gloom" factor can set in as soon as they discover that everything is not perfect on the first try. Reassuring them and showing them a few tricks of the trade can go a long toward increasing their confidence that they can tackle new challenges and overcome them. As always, however, let the newcomer handle the controls as much as possible.</p>
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<h3>What to Expect from the Doublet</h3>Initially, newcomers are simply overjoyed to hear signals on the bands and to be able to make contact with some of them. Eventually, however, they will come up with a variety of questions. Why can I hear the 1s and 2s, but not the 4s and 5s? Why do I hear near-by stations on 80 and 40, but lots of DX on 15 and 10?
|
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<p>Part of the answer lies in the nature of the ham bands, but part of the answer also lies in the antenna itself. An all-band doublet produces a different radiation and reception pattern for each of the ham bands. In addition, the angle at which the radiation goes out and comes in most effectively varies from band to band, with the higher bands generally having lower angle radiation than the lower bands. (This accounts in part for better DX results on the upper bands.)</p>
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<p>Although providing a complete set of patterns for all versions of the doublet would require lots of space, I can at least provide a small rogue's gallery of some patterns.</p>
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<p>Let's assume that we have a 135' doublet (plus or minus 10') at about 50' in the air. What sort of patterns would this antenna make for each of the Novice CW bands? Making allowances for the highly variable effects of terrain in the general region and the ground clutter that surrounds most homes, we can expect something like the following patterns for each band. Remember that the upper azimuth pattern in each set assumes the doublet is aligned from left to right. It is taken at the elevation of maximum radiation (except for 80 meters). The lower elevation patterns are taken along the strongest lobe of the antenna's pattern on that band, whichever way that lobe might be pointed. Azimuth patterns generally tell us in which direction over how broad a span our signals go, while elevation patterns tell us at what angle most of our signal hits the ionosphere, to be reflected back toward earth and a receiving station.</p>
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<p>The 80-meter azimuth pattern is taken at an elevation angle of 45 degrees. As the elevation pattern shows, most of the radiation is above this angle. Some hams call the relatively low dipole a cloud- burner. Although this is not a DX antenna, there is plenty of useful radiation for all kinds of excellent 80-meter QSOs.</p>
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<p>On 40 meters, the all-band doublet has a narrower pair of lobes, but the radiated signals in the primary directions will be stronger (and reception more sensitive). The elevation angle of maximum radiation is 39 degrees. However, note that there is a lot of energy being sent out (and received) at lower angles. Hence, the possibilities for DX improve. However, the antenna proves most useful for cross-country QSOs ranging from 800 to 2400 miles, depending on the time of day. These will mostly be broadside to the antenna wire.</p>
|
||||
<p>If we had installed the antenna as an inverted-Vee, with the wires sloping downward from a central support, there would be a few modifications to the pattern. Instead of a peanut, the azimuth pattern would be more oval, giving more reception and less rejection off the ends of the antenna. The angle of maximum radiation would also be just a bit lower, although maximum signal strength at the peaks of the major lobes would be down just a bit. For general operating, the differences are not likely to be noticed without a side-by-side test.</p>
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<img src="edu6-6.gif" width="636" height="756" border="2" vspace="5" hspace="9">
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<p>On 15 meters, the antenna is 3 wavelengths long. Note that there are 3 major lobes on each side of the wire. The stronger outer lobes are about 45 degrees off broadside. The elevation angle of maximum radiation is about 13 degrees, well down into DX territory. Since 15 is a good DX band, it would be nice to align the antenna so that one of the major lobes points at a desired DX territory.</p>
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<img src="edu6-7.gif" width="634" height="762" border="2" vspace="5" hspace="9">
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<p>On 10 meters, the doublet is 4 wavelengths long, and there are 4 major lobes on each side of the wire in the azimuth pattern. The elevation angle of maximum radiation has dropped to 10 degrees, and the antenna is capable of allowing us to work a lot of DX--if one of the main lobes is pointed in the right direction. The main lobes are about 35 degrees from the ends of the antenna wire.</p>
|
||||
<p>Newcomers are becoming more and more sophisticated about antenna patterns, since a few appear in almost every issue of the amateur radio magazines. However, what the patterns really mean may not be clear. Instructing newcomers in how to use azimuth and elevation patterns will help them make better use of the large amounts of antenna information available these days.</p>
|
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<p>One especially important lesson to teach is that all of these patterns have limitations, since they are generated by computer rather than by actual measurements made of the performance of actual antennas. First, the computer modeling programs use a level ground, which is not the terrain for many hams in the U.S. Hilly or mountainous terrain may vary antenna patterns by a significant margin. Second, the patterns assume a level antenna wire, with none of the droops, zigzags, and other shape imperfections we mentioned earlier. However, none of those imperfections will have a significant negative effect on antenna performance. They will just shift a lobe or two by a little bit.</p>
|
||||
<p>The best use of patterns like these is to establish some very general expectations about antenna performance. For example, we might expect an azimuth pattern of the 100' version of the doublet to have only 3 lobes on each side of the wire; and the 67' long version would show only two lobes on each side. However, if the antennas are all at the same height, we would expect the elevation patterns to be similar for each band.</p>
|
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<h3>Antenna Maintenance</h3>Every piece of amateur radio equipment deserves regular preventive maintenance. The antenna system is no exception. In fact, the antenna system--including the antenna proper, the feedline, and the antenna tuner--require special attention just because they seem so immune to harm.
|
||||
<p>However, here is a list of things that can happen to your antenna system that can adversely affect performance:</p>
|
||||
<pre>1. Antenna:
|
||||
wire corrosion
|
||||
wire breaks inside strong insulation
|
||||
wear on support ropes or lines
|
||||
wear or corrosion of solder joints at the feedpoint
|
||||
2. Feedline:
|
||||
build-up of dirt
|
||||
hidden breaks
|
||||
changes in the nearby metals
|
||||
3. Antenna Tuner:
|
||||
dust, dirt, tarnishing of the coil
|
||||
dirt between capacitor plates
|
||||
dirty switches</pre>
|
||||
<p>All of these items assume that we have taken generally good care of everything.</p>
|
||||
<p>The cure for all these evils is a regular maintenance program to examine and clean everything before it causes trouble. In addition, items showing wear can be replaced while the situation is under control, not during a contest or field day.</p>
|
||||
<p>Good maintenance begins at the time of building the antenna and feedline system. Raising the antenna should also mean that it can be lowered. Hence, the use of pulleys, eye-bolts, and other means of passing the rope or support line is essential to a good antenna installation. Passing the rope over a crotch of a tree is a good method for finding the rope immovable in a couple of years, as the tree grows right over it.</p>
|
||||
<p>Be certain that all connections between the feedline and the antenna wire are mechanically solid and well soldered. Do not rely on solder for the mechanical connection. In some parts of the country, it may be useful to seal the solder connection, since chemical salts in the air may break down the solder joint.</p>
|
||||
<p>Even if you use a ladder-line "grabber" device, be sure that there are no sharp edges against which the line may rub and break. In fact, the first maintenance should be about 4 months after initial construction as a check to ensure that all work was well done. Thereafter, a check at least once a year is wise.</p>
|
||||
<p>Many hams wax antenna wires with one of the automotive waxes designed to go on metals. They also contain cleaners that remove dirt, grime, and some tarnish to the wire during reapplication.</p>
|
||||
<p>Similar measures also apply to feedlines. Some doublet users have noticed that the antenna tuner settings require a little change during rain showers. While the water on the line may not create significant losses, it nevertheless pays to clean the feedline during a regular maintenance session. Again, automotive polish applied to vinyl-coated feedlines not only helps shed water, but also cleans dirt build-ups from particulates and chemicals in the air.</p>
|
||||
<p>One often neglected area of maintenance is the point where the line enters the house. Because the temperature may be vastly different indoors relative to outdoors, the line and its insulation can undergo stress and wear. If the passage is filled initially with fiberglass or a similar insulation to protect from drafts, the material can become packed with dirt and insects. Periodically changing the insulation-- and even the line section in this area--can help maintain the antenna system at full efficiency.</p>
|
||||
<p>The antenna tuner also needs a good periodic cleaning to remove dust and coatings that accumulate just from sitting in the living environment. A fine bottle-type brush (electric shaver type?) is good for catching dust between capacitor plates, as is some contact cleaner on a lintless rag. However, be sure the cleaner is non-toxic.</p>
|
||||
<p>Coils require special care. Many have tinned or silvered coatings, and tarnish can be a problem. It can even degrade the contact between the turns of a rotary coil and the wheel that contacts the turns. Try to clean the coil with non-abrasive materials to avoid removing the finish, since the copper underneath may tarnish even faster.</p>
|
||||
<p>While doing a general cleaning, inspect all connections. A good- looking solder joint to a coax connector might reveal a weakness after a period of time. Switch contacts may need cleaning and even replacement. Tightening all chassis and case screws (unless the instruction book explicitly says not to in some instance) is usually good practice, especially those screws that form part of the ground common of the tuner.</p>
|
||||
<p>Instructing newcomers in good maintenance practices is essential in this world in which almost all consumer electronics are marked "Do not open, No user parts inside." The entire amateur station represents a new level of responsibility for the licensee. He or she is responsible for the care and upkeep of the equipment to ensure that it meets technical specifications set by regulation. The only way for many to meet this need with respect to transceivers is to send them back to the factory for periodic servicing. However, almost every ham is able to perform many of the maintenance needs of the antenna system. Setting good habits as the new ham walks into the door of his or her new shack is to set a good habit for a lifetime.</p>
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<p>The all-band doublet is so deceptively simple an antenna that it seems to beg for neglect--until it quits working or falls down. Yet, a regular schedule of maintenance once or twice a year can make the antenna operate reliably for many years.</p>
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||||
<p>Of course, if the antenna does become a victim of weather, falling trees, or other accidents, replacing it is a straightforward exercise, made easier by having done it once already. Not only that, but replacement is easy on the budget. In fact, it may be impossible to find an antenna that does so much for so little as the all-band doublet.</p>
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<p><i>From</i> Proceedings of the 1998 National ARRL Education Workshop<i>, (Newington: ARRL, 1998), pp. 39-46 © L. B. Cebik, W4RNL. Data may be used for personal purposes, but may not be reproduced for publication in print or any other medium without permission of the author.</i></p>
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<h1><img src="../images/edu.gif" align="left" width="100" height="83" border="2" vspace="5" hspace="9"> <img src="../images/w4rnlwwr.gif" align="right" width="99" height="83" border="2" vspace="5" hspace="9"> QRP<br>
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A Newcomer's and Old-Timer's Challenge</h1>
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<h3>L. B. Cebik, W4RNL</h3>
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<p>QRP is a very old radio-telegrapher's Q-signal meaning "Reduce power." If followed by a "?" the signal means "Shall I reduce power?" There are literally thousands of amateurs throughout the world who answer with a resounding "Yes!"</p>
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<p>In the world of QRP operators, the term is defined loosely as operating with a power of 5 watts on CW and 10 watts PEP on SSB. If you think that you cannot do much with that little power, consider these facts. QRPers regularly earn DXCC and other DX awards. QRPers have made contacts garnering thousands and sometimes tens of thousands of miles per watt. QRPers regularly accumulate scores in the larger amateur radio contests that rival or exceed the scores of high power stations.</p>
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<p>QRPers often repeat a longstanding slogan: "Power is no substitute for skill." For newcomers and old timers alike, the slogan presents a special challenge. With the amateur bands becoming ever more crowded and with more of what The Old Man (Hiram Percy Maxim, the original W1AW) would have called "rotten operators" using more space, we must all increase our skills in every aspect of amateur radio in order both to enjoy our hobby and to effectively render public service through it.</p>
|
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<p>No better means of perfecting skills in every aspect of amateur radio exists than making the decision to forego power for QRP operation. There are, of course, operating skills to be mastered and honed. QRP also offers the chance to develop our building skills through a wide variety of compact but highly competent kit transceivers. With a few batteries, one can take QRP to the field (and not just on Field Day) to enjoy that special challenge. It includes not only the ability to operate and to keep the station going, but as well to install an antenna that is easy to carry, is easy to put up and take down, and is effective.</p>
|
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<p>For both newcomer and old timer, QRP offers one other significant benefit: it can be very economical. It is not unusual to find an operator whose single-band transceiver, antenna tuner, keyer, paddles, and antenna have left him a good bit of change from a $200 bill.</p>
|
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<p>However, the first steps into QRP are often (and perhaps unnecessarily) the source of fear and trepidation. We have become so used to the modern 100-watt output transceiver that the thought of making lots of contacts with 1/20th that amount of power seems almost impossible. And how is one to be able to compete on the air with the so-called "big guys?"</p>
|
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<p>Introducing the newcomer to QRP therefore takes considerable sensitivity and patience, as well as good practical guidance. The following notes are not designed to be a tutorial on QRP itself so much as a small and incomplete set of suggestions for helping someone over the threshold into QRP.</p>
|
||||
<h3>Step 1: Making a QRP Contact</h3>There is an old theory in amateur radio that is akin to antique ways of teaching kids to swim: throw them in and let them sink or swim. In this case, the parallel would be to tell the newcomer to just go ahead and make a contact using low power.
|
||||
<p>However, there are a number of things we can do to help the newcomer get his or her feet wet and learn what to expect of QRP. This assumes that the newcomer has a fairly standard transceiver in the 100- watt output class.</p>
|
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<p>First, we can help the student to learn what QRP sounds like. If possible, make arrangements with a local who can control rig power reasonably accurately and who has a strong signal (without overload) at the student location. Have the other station reduce power in definite steps, starting at 100 watts and ending up at about 5 watts (or even 1 watt). The 20:1 power reduction between 100 and 5 watts will show up as between 2 and 3 S-units, depending on the meter calibration (or lack of it).</p>
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<p>If the local was S9 before, then S6-7 will still be quite strong. The newcomer has learned that QRP signals are not quite so weak as he or she might have suspected. Having the student then practice copying very weak signals (as QRM and QRN permit) is a good way to build confidence that he or she can copy a QRP signal.</p>
|
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<p>Next, have the newcomer start reducing power in definite increments, again with the local using 5 watts or less. Have the local give signal reports at each level. It is important here also to use honest readability reports, rather than the standard R5. However, for this experiment, the R-report should not change by much, if anything.</p>
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||||
<p>When the newcomer hits 5 watts and exchanges signal reports with the local--also running 5 watts--interrupt the proceedings. Congratulate the newcomer on making his or her first QRP-to-QRP contact. Try to ensure that the local QSLs with a QRP notation for the newcomer's records and long-term memories.</p>
|
||||
<p>This exercise can be repeated, but without pre-arrangement, until the newcomer is comfortable making his or her own contacts. After a while, a new thought sets in: why should one consume all the electrical energy it takes to keep the big rig running when all that QRP requires is a low power transmitter and a sensitive, stable receiver with a good QRM filter? At this point, most hams asking this question become QRPers for life.</p>
|
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<h3>Step 2: Finding Other QRP Newcomers</h3>Many folks do not realize that there are both þregularþ and Novice QRP calling frequencies in the U.S. Here is a list of the Novice frequencies for reference.
|
||||
<pre> Band CW SSB
|
||||
80 3.710
|
||||
40 7.110
|
||||
15 21.110
|
||||
10 28.110 28.385</pre>
|
||||
<p>Have (and help) the newcomer to listen on or near these frequencies for signals. Weak signal strength is not always a sign that the station is QRP. Some low power stations add QRP after signing their calls; others do not.</p>
|
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<p>Not only Novices appear at these calling frequencies, but experienced operators call CQ there also. They are anxious to help the newcomer make QRP contacts to build both skills and confidence. So a newcomer should not be afraid to answer a station that is obviously not a Novice. The other operator will be glad to adjust his or her code speed to the level of the newcomer. This is an old and honored tradition among experienced hams on CW and applies at all power levels.</p>
|
||||
<p>On 10 meters, there are Novice privileges on SSB. At the present time, SSB QRP is just beginning to draw more attention. One factor influencing this increase is the availability of SSB kits. I suspect that once the initial surge of 10-meter DXing and 10-10 work calms down as 10 meters opens up on a regular basis, we shall hear 10-meter QRP on the Novice calling frequency. I have worked a number of 10-meter QRP SSB stations, most notably a completely solar-powered station using about 1 watt. He was S5 or better and completely competitive with the QRO stations.</p>
|
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<p>When the newcomer advances past the Novice to the General level, a large world of QRP will be opened to him or her. There are QRP calling frequencies in the U.S.A. on all of the ham bands from 160 meters through 2 meters. One incentive toward advancement is for the newcomer to understand what will be opened for use. Therefore, for reference, here are the remaining US QRP calling frequencies for each band:</p>
|
||||
<pre> Band CW SSB
|
||||
160 1.810 1.910
|
||||
80 3.560 3.985
|
||||
40 7.040 7.285
|
||||
30 10.106
|
||||
20 14.060 14.285
|
||||
17 18.096
|
||||
15 21.060 21.385
|
||||
12 24.906
|
||||
10 28.060 28.885
|
||||
6 50.060 50.885
|
||||
2 144.060 144.285
|
||||
144.585 (FM)</pre>
|
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<p>European QRP calling frequencies differ from those used in the U.S. due largely to differences in amateur radio frequency assignments. For those wishing to chase QRP DX, the European QRP calling frequencies are these:</p>
|
||||
<pre> Band CW SSB
|
||||
160 1.810 1.843
|
||||
80 3.560 3.690
|
||||
40 7.030 7.090
|
||||
7.060
|
||||
30 10.106
|
||||
20 14.060 14.285
|
||||
17 18.096
|
||||
15 21.060 21.285
|
||||
12 24.906
|
||||
10 28.060 28.360
|
||||
6 50.060 50.285</pre>
|
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<h3>Step 3: Getting Involved in QRP</h3>QRP is more than just operating at 5 watts or less. It is almost a frame of mind that encompasses many different activities. One of the best ways to identify or even generate one's interests is to become involved with local, area, or even national QRP organizations.
|
||||
<p>If there is a local or area QRP club, the newcomer should be encouraged to attend meetings or get-togethers, depending on the groupþs nature. Some clubs, like the Michigan and Colorado QRP Clubs, hold regular meetings. These are often informal, often with a meal, program, and some show-and-tell. The show-and-tell may involve some new kit just built, some QSL cards for significant contacts, or even some old-time gear that was used for QRP before the days of solid state.</p>
|
||||
<p>Other groups hold nets or on-the-air meetings. Still others meet once or twice a year, sometimes at a picnic, sometimes at hamfests.</p>
|
||||
<p>At last report (which is not likely to be too accurate), there were QRP clubs in Arizona, Arkansas, California, Colorado, Georgia, Illinois, Michigan, Missouri, New England, New Jersey, Ohio, Oklahoma, Pennsylvania, Texas, Washington, and Wisconsin.</p>
|
||||
<p>One good way to meet other QRPers is to join one of the e-mail lists devoted to QRP. QRP-L (@Lehigh.edu) is the largest QRP list. On one side of the coin, it can overwhelm someone not used to receiving 50 messages a day via e-mail. However, it does represent the entire spectrum of QRP interests: operating, building, problem solving, field operations, and helping newcomers.</p>
|
||||
<p>Subscription instructions appear in the section of this article devoted to QRP resources. Learning how to make the best use of an e- mail list is itself an art. Knowing when to send a message to the entire list and when to address one to a specific individual takes a little practice. However, once a person has had a few questions answered, the process grows more natural.</p>
|
||||
<p>Another avenue of involvement is to join one or more of the clubs sponsoring regular journals. A list of some of those organizations also appears within the resource section of this article. Also given are costs, contact people, and a brief note on what to expect from the journal.</p>
|
||||
<p>QRP ARCI is the <b>QRP Amateur Radio Club International</b>, a venerable US-based QRP organization that began many years ago when dropping power to 100 watts was considered a big step in the right direction. Today, QRP ARCI adheres to the 5-watt philosophy, and many members encourage milliwatting, the reduction of power to levels below 1 watt so that power may be given in milliwatts. Microwatting is not uncommon among members.</p>
|
||||
<p><i>The QRP Quarterly</i>, the journal of QRP ARCI, is one of the most diverse of all in its content. It not only offers technical articles, but also has information on operating, club awards, and club-sponsored operating activities.</p>
|
||||
<p>Each of the other journals listed (and others not listed) in the resource section has something unique to offer. Many QRPers support as many of them as possible (if only to be sure that something new does not slip by unread). Every newcomer should be encouraged to support at least one of them. Reading new things about QRP on a regular basis is not only a good way to increase one's knowledge; it is also an excellent pathway to developing new interests.</p>
|
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<h3>Step 4: Selecting One or More Interests</h3>QRP is not one world within ham radio; it is many. The beauty of the situation is the fact that anyone can inhabit as many (or as few) of these worlds as he or she has time and interest to give. Here is a short list of some of the activity areas within QRP.
|
||||
<p>1. <b>Operating</b>: General operating to make QRP contacts remains the focal interest of most QRPers. However, there are some special operating arenas that deserve note.</p>
|
||||
<p>a. <b>Field Operation</b>: Since QRP equipment is so compact and can often be operated from batteries, many QRPers like to take to the field and set up portable stations on hilltops, campgrounds, and similar locations. Part of the fun lies in developing an ever-improving station for this purpose, including antennas that are light to carry, easy to assemble, and effective on the air. Many field operators would enjoy the company and help of a newcomer as he or she learns the ropes (sometimes literally) of operating this way in exchange for helping to carry things, assemble the station, and help with the operating and logging.</p>
|
||||
<p>Here is a list of what an ardent field operation QRPer might take with him or her:</p>
|
||||
<ul>
|
||||
<li>1. Single-band rig for favorite band.</li>
|
||||
<li>2. Compact antenna tuning unit (ATU or transmatch).</li>
|
||||
<li>3. Wire antenna--often a random length wire to toss over a tree limb, a wire dipole, or a doublet.</li>
|
||||
<li>4. Transmission line--for the dipole, thin coax; for the doublet, TV twinlead.</li>
|
||||
<li>5. 2 batteries--main and back-up, usually 1 to 6 Ampere-hour gel cels.</li>
|
||||
<li>6. Hand key or keyer paddles--keyer itself is usually inside the transceiver case.</li>
|
||||
<li>7. Log book and 2 pens or pencils (one always breaks).</li>
|
||||
<li>8. Something on which to rest the rig and ATU--may be a table, a converted packing case, or even a large piece of foam with cutouts: the object is to keep the equipment mechanically stable during operation.</li>
|
||||
<li>9. Something to sit on, ranging from a foam pillow to a camping stool.</li>
|
||||
<li>10. Refreshments</li>
|
||||
<li>11. Safety equipment--depending on the remoteness of the site.</li>
|
||||
</ul>
|
||||
<p>b. <b>Contest Operation</b>: Many QRP organizations sponsor a number of different types of contests, from short þsprintsþ to longer efforts. Rarely are QRP contesters so abbreviated in their operating ways that they will not take time out to make sure a newcomer has every part of the required exchange. And when a QRPer wishes you "Good luck!" at the end of the contact, he or she means it.</p>
|
||||
<p>An alternative to strictly QRP contests are the "big" contests, many of which have a special QRP category. Here the challenge is to compete for contacts with higher power stations. Most QRP contesters do not sit and call CQ, but instead search for other stations calling CQ. This "search and pounce (SAP)" method, as Rich Arland, K7YHA, once called it, has run up scores for QRP operators that would have been respectable in any category of the contest.</p>
|
||||
<p>c. <b>Fox-hunting</b>: A recent QRP phenomenon is the fox hunt. Everybody knows who the fox is, where he is, and what his frequencies will be and at what times he will be on the air. The trick is to catch him. Everything is informal, so even failure to get the fox this time brings a determination to get the next one.</p>
|
||||
<p>d. <b>Milliwatting and microwatting</b>: Eventually, 5 watts becomes too small a challenge for some QRPers. They reduce power first to 1 watt and then even lower. One of their major challenges is to measure accurately the actual amount of power they are sending to the antenna. A second challenge is to be heard at all. Schedules with like-minded low power operators are a way of life, and sometimes they use special code words to be sure they were actually heard. Those who engage in this portion of QRP work usually have well-trained ears, which are often a better signal discriminator than the very best DSP filters available. Good ears and a good fist are important skills for all QRP operators.</p>
|
||||
<p>2. <b>Building</b>: Many QRPers are lifelong builders of ham gear and accessories. One of the appeals of QRP is that rigs can be simple enough for the average ham to build from a kit and for the more technically inclined to design or redesign. Letþs break this area down into several areas to see how a newcomer might be transformed from an appliance operator into a home brewer.</p>
|
||||
<p>a. <b>Kit Building</b>: Kit building from Heath and other now-departed sources was once a routine part of amateur radio. The complexity of modern transceivers has largely ended this trend, except in one area: QRP. A number of large and small companies have devoted considerable effort to designing a variety of transceivers that the average ham can build and successfully use. A partial list of kit-makers appears in the resource section.</p>
|
||||
<p>For the newcomer, even a fairly simple kit can seem mysterious without guidance. Helping the newcomer to select his or her first kit and then guiding the person through the building process so that the result is something successful and useful for the station are two important areas of effective Elmering. However, once the first kit is done, a third area becomes important: guiding the newcomer to the next stage in challenge rather than to the most challenging kit on the market.</p>
|
||||
<p>One very important set of lessons that almost demands the aid of an Elmer is the art of testing the gear that one is building. Only a very few of the simplest kits can be built, smoke-tested, and then found to work or not. Whenever there are two or more stages, each can be tested as they are built, so that any problems are discovered early on, when they are easy to identify and relatively easy to fix. Some kit instructions proceed in this manner; other kits require experienced intervention for such testing. Helping the newcomer to understand this process is a piece of teaching likely to last a lifetime in the student.</p>
|
||||
<p>b. <b>Tinkering</b>: The term "tinkerer" was once a highly respectable word for the basement, garage, or shop builder and inventor. Many QRPers are avid tinkerers. Some like to modify and improve the kit they have just finished building and testing. Others like to build and revise circuits they find in magazines. Still others like to build from scratch.</p>
|
||||
<p><i>SPRAT</i>, the journal of the G-QRP Club is more than 50% devoted to tinkering in the best traditions of modifying and improving circuits and gear. In the issue I happen to have in hand, there are two complete fairly complex projects, with a fistful of small circuits--one an ultra-simple transmitter, some simple test detectors, a junk-box filter, a modification of an existing circuit, and a couple of handy circuits that a builder might use in his or her own more complete design.</p>
|
||||
<p>In contrast, but not too much contrast, is <i>QRPp</i>, the journal of the Northern California QRP Club (NORCAL). NORCAL has become very well known for its club-designed and produced transceiver kits. The particular issue of <i>QRPp</i> that I happened to pick up has three complete projects, plus two more extensive articles on both the electronic and mechanical details of modifications to two rigs--plus the start of a multi-part tutorial. It also has a good collection of short items.</p>
|
||||
<p>Is one journal preferable to the other? It depends on one's interests and the emphases within those interests as to which journal might be more useful or valuable.</p>
|
||||
<p>Whatever the special nature of one's interest in tinkering, the beginning tinkerer needs help getting started. Learning where to get parts, which parts to get, how to handle the parts, when to use which of similar parts are all lessons needing a good source of information and advice. There are dozens of pitfalls to the process of designing and building a prototype, and a little help in avoiding even a few of them can transform discouragement into the persistence that brings success.</p>
|
||||
<p>3. <b>Antennas</b>: There is a debate within the ranks of QRP operators: whether it is proper to use sophisticated high gain antennas atop tall towers or whether the QRPer should use the simplest antennas possible to go along with the simple gear he or she may be using. The debate really describes two kinds of QRPers. First, there are those who simply wish to use the least power possible as a means of reducing QRM. Their goal is to achieve as much as possible with the lowest reasonable power. These folks tend to use the best antennas they can obtain or build. Second, there are QRPers who are committed to doing the absolute most with the absolute least, perhaps with the idea that someday they will be able to do everything with absolutely nothing. These dedicated minimalists tend to insist on simple antennas. Since many of them are also lovers of field operation, their desire for simple antennas also has a practical side. Whatever the reason or direction, QRPers tend to experiment with antennas more than most folks. Wire is the favorite antenna material, and the lighter the better. However, the variety of materials used to support the wire ranges from fishing rods to PVC to towers to whatever will hold it in position.</p>
|
||||
<p>Since a good antenna--however defined--is crucial to effective QRP operation in any of the categories we have listed, good instruction in antenna basics is absolutely essential for the newcomer to QRP.</p>
|
||||
<p>But antenna basics also come in two parts: antennas as electronic components and antennas as mechanical devices that require good construction and maintenance. Even learning to analyze the antenna possibilities and restrictions of one's own yard can benefit from a practiced eye, plus a little help in getting the antenna in the air.</p>
|
||||
<h3>Step 5: Learning More</h3>A brief article like this can do little more than sample the opportunities for helping the newcomer to master QRP. Indeed, this one arena of amateur radio often masters the ham, becoming a life-long compulsion.
|
||||
<p>Nevertheless, it would be inappropriate to suggest that QRP is the exclusive interest of amateur radio. Even the major QRP organizations recognize that there are conditions, needs, and services that may call for higher power levels from time to time. And all of these areas also call for effective Elmering.</p>
|
||||
<p>However, QRP can become so consuming an interest that the practitioner always desires more information about one or another thing in the field. Therefore, the resources section also contains a starter list of books, some devoted to QRP operating, others devoted to QRP circuitry and equipment. Only antennas are not included, since the QRPers antenna books are also every ham's antenna books.</p>
|
||||
<p>In the end, all of ham radio is enriched by whatever it is that each ham learns. And it is enriched even more by whatever we pass on to others.</p>
|
||||
<h3>QRP Resources</h3>The following lists are not complete, but are intended to get both the newcomer and the instructor started in the adventure of QRP operating and building. [<i>Special Note</i>: Since the time that I wrote this article, many of the resources in terms of periodicals, web-based lists, parts and kit supplier etc., have changed. However, QRPARCI and G-QRP remain enduring focal points for obtaining updated information.]
|
||||
<h4>Periodicals</h4>1. <i>QRP Quarterly</i>: Published quarterly by QRP ARCI (QRP Amateur Radio Club, International), <i>QQ</i> comes with annual membership ($15 US, $18 CA, $20 DX). The 40 8.5x11" pages contain a good mix of technical articles on construction, circuits, antennas, modifications, and test equipment, along with operating and award information, editorial views, QRP philosophy, contest dates and results, and member news. The "Idea Exchange," compiled by Mike Czuhajewski, WA8MCQ, has been a long- standing favorite. Editor Ron Stark, KU7Y, is backed by 8 contributing editors to maintain a diverse publication. Membership dues- subscriptions go to Ken Evans, W4DU; 848 Valbrook Court; Lilburn, GA 30047 USA.
|
||||
<p>2. <i>SPRAT</i>: The "Small Powered Radio Amateur Transmitter" or <i>SPRAT</i> is published by the G-QRP Club 4 times each year. Under the editorship of Rev. George Dobbs, G3RJV, each 44-page issue in 5.75x8.5" format contains 60% construction articles in each issue (circuits, antennas, test equipment, etc., both basic and advanced, with some pcb layouts) from many different countries. Each issue also contains award, operating, contest, G-novice, SSB, VHF, and member columns and news. SPRAT comes with membership in G-QRP Club, which can be obtained by U.S. residents for $14 per year from Bill Kelsey, N8ET, Kanga US, 3521 Spring Lake Drive, Findlay, OH 45840, USA</p>
|
||||
<p>3. <i>QRPp</i>: NORCAL, the QRP Club of Northern California, publishes a feature-packed 72-page quarterly in 5.75x8.5" format. Edited by Doug Hendricks, KI6DS, the journal features over 20 articles per issue, mostly devoted to technical and construction topics, including new designs, conversions, improvements, and modifications. Some issues feature NORCAL club projects, such as the NORCAL 40(A), the Sierra, and the recent "38 Special." Cost is $15 per year from The QRP Club of Northern California; Jim Cates, WA6GER; 3241 Eastwood Road; Sacramento, CA 95821 USA. Make subscription checks payable to Jim Cates, not NORCAL.</p>
|
||||
<p>4. <i>Low Down</i>: This award-winning journal of the Colorado QRP Club appears 6 times per year. Each 40-page 5.75x8.5" issue, edited by Rich High, W0HEP, contains technical articles, rig profiles and other equipment reviews; overseas QRP operating features, club member profiles, and CQC activities news. Technical Editor Paul Harden, NA5N, provides a regular circuitry or technical feature, while W4RNL supplies "Antennas From the Ground Up." <i>Low Down</i> comes with membership for $15 per year from the Colorado QRP Club; P.O. Box 371883; Denver, CO 80237-1883 USA.</p>
|
||||
<p>5. <i>Lo-Key</i>: Published 4 times each year, this 32-page 5.75x8.5" journal comes with membership in the CW Operators QRP Club of Australia. Annual cost is $14 A from Kevin Zietz, VK5AKZ; 41 Tobruk Avenue; St. Marys, SA 5042 Australia. As a service to U.S. hams, N8ET accepts subscription money at Dayton and forwards it in order to assist with currency conversion. Edited by Don Callow, VK5AIL, each issue contains two to three construction articles/issue, including advanced ideas, equipment modifications, keyers, etc. (some with parts kits available); along with awards, contest, and net program news.</p>
|
||||
<h4>Some Books of Special Interest</h4>Adrian Weiss, W0RSP, <i>History of QRP in the U.S.</i>, 1924-1960 (Milliwatt Books: 526 N. Dakota, Vermillion, SD 57069), 1987, $15.00 (includes 1st class postage), 200 pp. A rigorous but personalized history of QRP by a professional historian and longtime QRPer, with extensive extracts from the original records published in QST and elsewhere.
|
||||
<p>Adrian Weiss, W0RSP, <i>The Joy of QRP</i> (Milliwatt Books), 1984, $23.00 (includes 1st class postage), 151 pp. An informal overview of QRP that emphasizes operating, but with a few projects; considered a classic.</p>
|
||||
<p>Brad Wells, KR7L, <i>Your QRP Operating Companion</i> (ARRL), 1992. $6.00, 96 pp. An introduction to QRP operating, including ragchewing, DXing, and contesting, with lists of QRP clubs and organizations, as well as net and calling frequencies.</p>
|
||||
<p>Dave Ingram, K4TWJ, <i>How to Get Started in QRP</i> (National Amateur Radio Association [NARA], P.O. Box 598, Redmond, WA 98073. 1992, $9.95, 131 pp. A beginners guide to QRP, touching on operating, commercial and home brew gear, accessories, antennas, VHF/UHF QRP, and battery and "natural" power.</p>
|
||||
<p>Richard Arland, K7YHA, <i>Low Power Communications</i>, Vol. 1-3 (Tiare Publications; P.O. Box 493, Lake Geneva, WI 53147), 1992, about 100 pages per volume. Price varies from $14.95 to $19.95 per volume. Volume 1 is a basic book on QRP, focusing on the newcomer to the QRP arena, helping him/her get off on the right foot. Vol. 2 is a more advanced volume featuring many top names in the QRP hobby (AA2U, N4BP, WB8VGE, etc.) telling how they pursue various facets of QRP, such as DXing, contesting, DXpeditions, antennas, satellites, milli/microwatting, and solar power. Vol. 3 is devoted to equipment evaluations: commercial, kit, new and used; how to buy used gear; also includes software and antennas.</p>
|
||||
<p>Dick Pascoe, G0BPS, <i>Introducing QRP: An Introduction to the History and Skills of Low Power Operating in the UK</i> (R. A. Pascoe), 1996, $8.00, 84 pp. A succinct introduction to the history of QRP, the basic equipment for QRP, and the operating techniques needed for QRP. Available in the US from Kanga, USA (see address under the kits listings).</p>
|
||||
<p>Joel Kleinman, N1BKE, and Zack Lau, KH6CP/1, Editors, <i>QRP Power</i> (ARRL), 1996, $12.00, 175 pp. "The best recent QRP articles from QST, QEX, and the ARRL Handbook." Designed to update QRP Classics for the 1990s, with chapters on QRP operating, construction practices, transceivers, receivers, and accessories.</p>
|
||||
<p>Paul Harden, NA5N, <i>The Electronic Data Book for Homebrewers and QRPers</i> (Five Watt Press), 1996, $20.00, 150 pp. QRP rig circuit analysis, component specification sheets, QRP operating aids, and QRP rig lab tests. Also includes the QRP Yellow Pages, by Rich High, W0HEP.</p>
|
||||
<p>Doug DeMaw, W1FB, <i>W1FB's QRP Notebook</i>, 2nd Ed. (ARRL), 1991, $10.00, 179 pp. Construction projects for QRP transmitters, receivers, and accessories; most projects have circuit boards available.</p>
|
||||
<p>Rev. George Dobbs, G3RJV, Ed., <i>G-QRP Club Circuit Handbook</i> (RSGB: Available from Kanga USA), 1983, $12.00. A compilation of QRP circuits from the pages of SPRAT from 1974-1982; considered a classic.</p>
|
||||
<p>Drew Diamond, VK3XU, <i>Radio Projects for the Amateur</i> (RSGB), 1995, $12.00, 130 pp. 30 chapters of projects and techniques for the QRP builder from the Australian point of view, but with parts available almost anywhere.</p>
|
||||
<p>Ed Noll, W3QFJ, <i>Solid State QRP Projects</i> (MFJ), $12.95. 52 QRP projects using transistors, FETs, and ICs without requiring extensive electronics knowledge.</p>
|
||||
<p>Of course, standard amateur radio reference books, such as <i>The ARRL Handbook for Radio Amateurs</i> and <i>The ARRL Antenna Book</i>, are recommended for every ham's bookshelf. However, if the newcomer is to make best use of these materials, special guidance by a long-term Elmer may be needed.</p>
|
||||
<h4>Kits and Equipment</h4>The following list of QRP kit and equipment makers is not complete, but will get you started in your exploration of inexpensive but challenging building projects. Listed are makers of multi-band and single-band transceiver kits, mostly CW, but some SSB, as well as some modular boards that can be combined into a full transceiver. Construction difficulty ranges from very easy to challenging. A number of station accessories, such as keyer and antenna tuner kits, are available from these and other makers.
|
||||
<pre>EMTech
|
||||
3641A Preble Street
|
||||
Bremerton, WA 98312 USA
|
||||
|
||||
Kanga US
|
||||
3521 Spring Lake Drive
|
||||
Findlay, OH 45840 USA
|
||||
(Note: Kanga US handles British Kanga and Hands kits, as well as other
|
||||
US kits.)
|
||||
|
||||
Oak Hills Research
|
||||
20879 Madison Street
|
||||
Big Rapids, MI 49307 USA
|
||||
|
||||
Small Wonder Labs
|
||||
Dave Benson, NN1G
|
||||
90 East Robbins Avenue
|
||||
Newington, CT 06111 USA
|
||||
|
||||
Ten-Tec
|
||||
1185 Dolly Parton Highway
|
||||
Sevierville, TN 37862 USA
|
||||
|
||||
Wilderness Radio
|
||||
P.O. Box 734
|
||||
Los Altos, CA 94023-0734 USA</pre>
|
||||
<h4>Internet Resources</h4>The most significant QRP e-mail list for U.S. hams is QRP- [email protected]. To subscribe to this list, send a message to [email protected] with no subject line entry and only the text SUBSCRIBE QRP-L [firstname] [lastname] [call] where you substitute your information for each [] and do not use the [] in your message. You will receive a verification message and should reply as instructed. QRP-L is a very active list, with well over a thousand subscribers. Exchanges range from operating notes to circuitry inquiries, with any topic relating to QRP operation being permitted. The G-QRP Club maintains an e-mail list in the UK for use by its members, and membership is certainly open to U.S. QRPers.
|
||||
<p>The World-Wide Web holds a basic resource for QRP that will provide many links to other pages of both relevance and interest. The URL is http://qrp.cc.nd.edu/QRP-L/ and the pages are maintained by Steve Hideg. Of special interest to the newcomer will be photographs Steve has taken of a wide variety of assembled kits for QRP work. Links to kit-maker pages will show additional photos of kits, both inside and out. The Web site is also linked to many of the archival documents of QRP-l, including a world-wide list of QRP clubs, an expanded list of periodicals, an equally expanded list of electronics books of interest to QRPers, and a list of antenna books.</p>
|
||||
<p>The abbreviated list of resources has only scratched the surface of what is available in each of the categories. Nonetheless, Elmers should be very selective in recommending materials, offering new resources only at the rate the newcomer can effectively absorb them.</p>
|
||||
<center>
|
||||
<img src="../images/colorbar.gif" align="middle" width="540" height="4">
|
||||
</center><br>
|
||||
<br>
|
||||
<p><i>From</i> Proceedings of the 1998 National ARRL Education Workshop<i>, (Newington: ARRL, 1998), pp. 30-38. © L. B. Cebik, W4RNL. Data may be used for personal purposes, but may not be reproduced for publication in print or any other medium without permission of the author.</i></p>
|
||||
<center>
|
||||
<img src="../images/colorbar.gif" align="middle" width="540" height="4">
|
||||
</center><br>
|
||||
<br>
|
||||
<a href="edu.html"><img src="../images/return.gif" align="bottom" width="40" height="40"> Go to Educational Notes Index</a><br>
|
||||
<a href="../radio.html"><img src="../images/rtnhome.gif" align="bottom" width="40" height="40"> Return to Amateur Radio Page</a><br>
|
||||
<p class="topics-footer">Topics: <a href='../topics.html#education'>Education</a></p><br>
|
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||||
<!DOCTYPE html>
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||||
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||||
<meta charset="UTF-8">
|
||||
<meta name="keywords" content="Education">
|
||||
<title>Youth Teachers and Tutors</title>
|
||||
<link rel="stylesheet" href="../styles.css">
|
||||
</head>
|
||||
<body>
|
||||
<center>
|
||||
<h1><img src="../images/edu.gif" align="left" width="100" height="83" border="2" vspace="5" hspace="9"> <img src="../images/w4rnlwwr.gif" align="right" width="99" height="83" border="2" vspace="5" hspace="9"> Youth Teachers and Tutors<br>
|
||||
or<br>
|
||||
Elmer Does Not Have to Be an Adult</h1>
|
||||
</center>
|
||||
<center>
|
||||
<h3>L. B. Cebik, W4RNL</h3>
|
||||
</center>
|
||||
<center>
|
||||
<img src="../images/colorbar.gif" width="591" height="3">
|
||||
</center>
|
||||
<p>There is an old picture of Elmer that may need a bit of retouching sometime soon. We show him (usually "him) as an older, kindly fellow looking over the shoulder of a youthful ham-to-be, gently guiding the youngster's preparations for the exam. Perhaps we can revise the picture this way: Elmer is a more experienced peer of the newcomer, sitting across a table, conversing with the newcomer eye-to-eye. In school rooms and school-sponsored clubs, where guidance into the role of an Elmer is available, recruiting youth teachers and tutors is both possible and desirable.</p>
|
||||
<p>Developing youth teachers and tutors is possible because the practice is already used in many programs. School systems throughout the country have introduced under various names the use of slightly older students to assist younger students in the mastery of many curricular skills. As well, we have long experience in many levels of student teaching, ranging from simple "show-and-tell" to formal individual and group reports.</p>
|
||||
<p>Developing youth teachers and tutors is desirable for several reasons. First, it develops a firmer commitment to amateur radio in all its aspects within the youth teacher or tutor. By exercising what we have learned so far in the service of helping others to learn the same thing, we tend to learn more fully and deeply--if for no other reason than the challenging questions from those we help. Moreover, we tend to prize more permanently those activities in which we have successes, and helping others learn is a very impressive sign of success.</p>
|
||||
<p>In addition, youth teachers overcome in the newcomer many of the barriers to learning occasioned by age and status differences. Questions we hesitate to ask the mature Elmer for fear of looking stupid become part of the normal conversational flow with our experienced peers. The net result is an enhanced view of the class or club as "ours," instead of being "their" (the older Elmers') activity. While certainly not a cure-all for everything that interferes with long-term commitments to amateur radio classes, clubs, and activities, the development of youth teachers and tutors can make a positive contribution to those commitments.</p>
|
||||
<h3>Teaching</h3>Many folks who are thrust into teaching situations take a wrong view of what "teaching" means. The most common misconception is that teaching means preparing a presentation to a group to inform them on some topic or another. While such presentations are often quite valuable, they miss the focus of teaching: the student.
|
||||
<p>Over my own years of teaching (35), I have picked up a different slant on teaching. "Teaching" means "helping to learn." Once we make the transition to this idea, our focus changes to those things that help our students to learn. This very thought gives us much more flexibility in trying to figure out how to get the job done, for we are no longer thinking primarily of ourselves as teachers. We are thinking of the student and what he or she is trying to learn. Whatever helps that process becomes useful, whether or not we happen to be the active ingredient in the teaching process.</p>
|
||||
<p>From this perspective, youth teachers and tutors are not simply ways to distribute our personal work load. They are instead excellent means of facilitating the learning process. Employed carefully, youth teachers and tutors can not only convey information and provide a patient vehicle for practicing the knowledge until it is firmly grasped, but as well experienced peers can pass along to the newcomer some intangible aspects of amateur radio. Among these are the spirit of challenge, the excitement of communications, and the dedication to service. Parental lessons and values that we come to appreciate only later in life are absorbed more naturally from those our own age who share more immediately in the difficulties of growing.</p>
|
||||
<p>Carelessly utilized, youth teachers and tutors who are unprepared for their roles or who are unwilling to exercise them can do more harm than good in the teaching process. Rather than these dangers being a reason to avoid using youth teachers and tutors, they are simply reasons to spend the extra effort to develop these members of the teaching team.</p>
|
||||
<p>The concept of the teaching team--the team that helps the newcomer to learn--is crucial in figuring out the best ways to utilize effectively and productively every resource to help learning happen. One of the ways that we can keep the youth members of the group returning for further service is to help them understand that they have special roles to play and that those roles are vital to the success of the team. The team may have a captain or a coach, but its achievements belong to everyone.</p>
|
||||
<h3>Youth Teachers</h3>The idea of giving our youth a significant teaching role seems at first daunting in light of the differential between their limited experiences and our far more extensive seasoning. However, if we look at the many small steps they have taken in the process of becoming teachers, we can gather some confidence in them. From their earliest school days, they have participated in one or another form of show-and-tell. Even in the elementary grades, they prepared and presented reports of educational value to their classmates. Finding appropriate teaching roles is simply a matter of using these experiences as a model and then finding appropriate units of material for them to teach.
|
||||
<p>Without probing into educational theory, here are some practical guidelines for developing and employing youth teachers.</p>
|
||||
<ul>
|
||||
<li>1. Give youth teachers small units of material to present in a finite time period that is only part of the group session.</li>
|
||||
<li>2. Help them organize their presentations, but do not block their creativity. They may come up with more ingenious visual aids than their leader.</li>
|
||||
<li>3. Select topics that they can master. First efforts might concentrate on operating subjects or general overviews, with the leader available to fill in technical detail.</li>
|
||||
<li>4. Support and supplement the teaching session. If you spot an error, do not correct it while the session is occurring or even immediately afterwards. Remember, you are not grading the youth teacher, but encouraging him or her. Simply incorporate a correction in a follow-up note later in the overall session.</li>
|
||||
<li>5. Let the youth teacher grow, encouraging but not demanding further refinements of knowledge and technique. Likewise, do not insist that everyone be a youth teacher. Some individuals will realize only later that they want to play a role in the formal teaching part of the team.</li>
|
||||
</ul>
|
||||
<p>As the overall leader, you can begin the process of developing both the skills and the confidence it takes to teach. One easy method is to regularly reserve time for folks to express their recent achievements, whether in the learning process toward a license or in the world of ham operations. You may spot reports that deserve fuller treatment and ask (apart from the group session to remove any pressure) the individual to make a longer report. You can also use well-placed questions in these sessions to aid the members in better articulating both the facts and the excitement of the achievement.</p>
|
||||
<p>You can also remove some of the barriers to good teaching, such as the use of adult-size tables and podiums, having specified places for reporters and teachers to stand, and other practices best reserved for later in life. Sitting comfortably around a table or in some other group arrangement, with the youth teacher situated in a comfortably familiar way, can do wonders for overcoming stage fright. And, by all means, be a good example.</p>
|
||||
<h3>Youth Tutors</h3>Teaching a group is only one half of the task. The best Elmering is a one-on-one affair in which the newcomer becomes a full person with highly individualized talents and weaknesses. Developing the spirit of individual assistance within the class or club can go a long way toward making it a permanent part of each member's natural way of thinking.
|
||||
<p>The process of developing a tutorial system can begin with something as simple as dividing the group into pairs for code practice, for prelicensing drill on question, or any number of other similar activities. These can be either mutual help sessions or activities in which the more experienced help the newcomers. Besides their primary function of reinforcing learning, these sessions will also help you identify potential tutors. Some of the group members will show a genuine enthusiasm for the task. You may detect that some of the experienced members do better in assisting with certain subjects or skills. These are observations you can capitalize on in developing the tutorial system within the group.</p>
|
||||
<p>There are many ways to organize a tutorial system more formally, and your choice may depend on circumstance. The range of options generally runs, on the one hand, from having a "big buddy" for each newcomer to follow through the entire initial licensing process, and on the other, to having topical specialists available for special help on demand. Tailor the style of the tutoring to the nature of the group and its special needs. Since needs may change over the years, so too might the tutoring system.</p>
|
||||
<p>In general, youth tutoring works best when there is a common study unit the tutor and the newcomer can work through together. This feature allows the session to have focus. However, encourage tutors to have some pure conversation time with the newcomer in order to let each person know the other. In addition, encourage tutors to let you know of any special circumstances that may arise in the course of tutoring. These may range from a unique problem facing the newcomer to the need for additional technical information to answer questions raised by the newcomer. Often, youth tutors will be more forthcoming with such notes if they contribute to the formulation of new things to teach that are for everyone.</p>
|
||||
<p>Youth tutors require guidance, especially is maintaining a suitably modest approach to the newcomers. Learning how to be proud of what we have learned well enough to pass on to the next newcomer, while not flaunting the achievement, is a difficult task, even for very experienced teachers. Therefore, guidance sessions for youth tutors should include continuous attitude training as well as the other elements necessary for success. (These other elements include comprehension of the study unit, good tutorial techniques, and feedback on newcomer progress.)</p>
|
||||
<h3>Conclusion</h3>These brief notes on youth teachers and tutors cannot hope to cover the entire subject. They are only an introduction designed to encourage their use in class and club situations where there is long-term contact among group members. Setting up a system of youth teachers and tutors requires more energy and involvement than merely making presentations. However, that effort translates into more energy and involvement expended by group members in helping each other. The end result is often a life time of dedication by more hams to amateur radio and to radio amateurs.
|
||||
<center>
|
||||
<img src="../images/colorbar.gif" align="middle" width="540" height="4">
|
||||
</center>
|
||||
<p><i>From</i> Proceedings of the 1999 National ARRL Education Workshop<i>, (Newington: ARRL, 1999), pp. 81-84. © L. B. Cebik, W4RNL. Data may be used for personal purposes, but may not be reproduced for publication in print or any other medium without permission of the author.</i></p>
|
||||
<center>
|
||||
<img src="../images/colorbar.gif" align="middle" width="540" height="4">
|
||||
</center>
|
||||
<p><a href="edu.html"><img src="../images/return.gif" align="bottom" width="40" height="40"> Go to Educational Notes Index</a></p>
|
||||
<p><a href="../radio.html"><img src="../images/rtnhome.gif" align="bottom" width="40" height="40"> Return to Amateur Radio Page</a></p>
|
||||
<p class="topics-footer">Topics: <a href='../topics.html#education'>Education</a></p><br>
|
||||
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|
||||
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||||
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||||
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|
||||
<head>
|
||||
<meta charset="UTF-8">
|
||||
<meta name="keywords" content="Education">
|
||||
<title>The Internet as a Teaching Tool</title>
|
||||
<link rel="stylesheet" href="../styles.css">
|
||||
</head>
|
||||
<body>
|
||||
<center>
|
||||
<h1><img src="../images/edu.gif" align="left" width="100" height="83" border="2" vspace="5" hspace="9"> <img src="../images/w4rnlwwr.gif" align="right" width="99" height="83" border="2" vspace="5" hspace="9"> The Internet as a Teaching Tool<br>
|
||||
Using It Well</h1>
|
||||
</center>
|
||||
<center>
|
||||
<h3>L. B. Cebik, W4RNL</h3>
|
||||
</center>
|
||||
<center>
|
||||
<img src="../images/colorbar.gif" width="591" height="3">
|
||||
</center><br>
|
||||
<p>The internet contains a wealth of opportunities to enhance the education of prospective hams and new licensees of all ages. The trick is to use it selectively and wisely. Like every other teaching tool, internet resources require careful evaluation, sometimes for deciding whether or not to use one at all, sometimes to find the best use for a good resource.</p>
|
||||
<p><b>What's Available on the Web:</b> The World Wide Web (WWW or simply the Web) contains a vast array of personal, commercial, organizational, and informational materials, some strictly text (with or without graphics), some embellished with audio and moving images. As teaching tools, we are most interested is the information available to us. In the amateur radio arena, what we can access would fill a library. Here is a partial list arranged by categories:</p>
|
||||
<center>
|
||||
<table border="4" cellpadding="4" cellspacing="4">
|
||||
<tr>
|
||||
<td><b>Operating Modes:</b></td>
|
||||
<td><b>Activities:</b></td>
|
||||
<td><b>Operating Aids:</b></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>CW</td>
|
||||
<td>Youth Radio</td>
|
||||
<td>RST</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>RTTY/PSK31</td>
|
||||
<td>Emergency Services</td>
|
||||
<td>Q-signals</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>SSTV</td>
|
||||
<td>ARES/Races</td>
|
||||
<td>Time Standards</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>FM</td>
|
||||
<td>Field Day</td>
|
||||
<td>Maps/Headings</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>ATV</td>
|
||||
<td>Fox Hunting</td>
|
||||
<td>Grid Squares</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>Packet</td>
|
||||
<td>DXing</td>
|
||||
<td>Call Look-up</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>FAX</td>
|
||||
<td>Nets</td>
|
||||
<td>Solar Flux</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>Satellites</td>
|
||||
<td>MARS</td>
|
||||
<td>Repeater Guides</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>.</td>
|
||||
<td>VECs/Examinations</td>
|
||||
<td>QSL Information</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td><b>Technical:</b></td>
|
||||
<td>County Hunting</td>
|
||||
<td>Beacons</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>Amplifiers</td>
|
||||
<td>.</td>
|
||||
<td>.</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>DSP</td>
|
||||
<td><b>Equipment:</b></td>
|
||||
<td><b>Organizations:</b></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>RFI</td>
|
||||
<td>Manufacturers</td>
|
||||
<td>FCC</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>RF Safety</td>
|
||||
<td>Dealers</td>
|
||||
<td>ARRL</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>Antennas</td>
|
||||
<td>Reviews</td>
|
||||
<td>(Other National Organizations</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>Transistors</td>
|
||||
<td>.</td>
|
||||
<td>in Canada, Great Britain,</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>Attenuators</td>
|
||||
<td><b>History:</b></td>
|
||||
<td>Japan, South Africa, etc.)</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>Transmission Lines</td>
|
||||
<td>Antique Radios</td>
|
||||
<td>AMSAT</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>Toroids</td>
|
||||
<td>Call Signs</td>
|
||||
<td>10-10</td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td>Microwaves</td>
|
||||
<td>Origins of "73", etc.</td>
|
||||
<td>TAPR</td>
|
||||
</tr>
|
||||
</table>
|
||||
</center>
|
||||
<p>This highly abbreviated listing is derived from one of several "ham link" sites: "AC6V Amateur Radio and DX Reference Guide" <a href="https://www.ac6v.com" target="_blank"><b>(https://www.ac6v.com)</b></a>. The actual main index page fills 4 complete sheets, and even includes separate references for the Wouff-Hong and the Rettysnitch.</p>
|
||||
<p>Notice that the ARRL is listed only once in the table. Actually, there are extensive references to the <a href="https://www.arrl.org" target="_blank"><b>ARRL site</b></a>, which has a long index of its own covering virtually every aspect of League activities and services. Not the least of these services are the special ones available to ARRL members.</p>
|
||||
<p>With so much available, the big task is becoming familiar with the resources and figuring out how best to use them.</p>
|
||||
<p><b>Print Supplements</b>: Some web pages can be downloaded in print form and then reproduced for students as class supplements. Not every web page is suitable for this use. Here are a few cautions to observe.</p>
|
||||
<ul>
|
||||
<li>1. Be very selective, so that you do not overload the student with paper. Familiarize yourself with a wide variety of selections on any topic so that you can select the very best available.</li>
|
||||
<li>2. Evaluate each potential paper supplement for clarity of writing and graphics, relative to the age group and background of the students. The key is to challenge students to increase their knowledge without making the challenge impossible to meet.</li>
|
||||
<li>3. Be sure you have permission to use the material. Most folks who place materials on the web are happy for you to use them, but obtain permission, regardless of whether the web page or site contains a copyright notice.</li>
|
||||
<li>4. Decide whether it is better to distribute an item to everyone or to keep it in a class reading file--to be handed out when there is a clear need and/or interest.</li>
|
||||
<li>5. Recheck the source site periodically for revisions and updates to the material presented. Technical information often requires corrections, while activities and regulatory information is subject to regular revision.</li>
|
||||
</ul>
|
||||
<p>Print reproduction allows an instructor to control student contact with material. Amid the many excellent presentations on various topics, there are items that display misconceptions and errors. Hence, the control afforded by print reproduction can usefully guide students to correct as well as readable material.</p>
|
||||
<p><b>Student Browsing</b>: As we approach Y2K, most students are likely to have direct access to the web, whether at home, in school, or through activity centers. This offers the student a special educational dimension beyond ordinary print materials: the excitement of discovering information for himself or herself. At the same time, this new dimension reduces the amount of control an instructor has over the absorption of misinformation or disinformation.</p>
|
||||
<p>Despite this danger, the instructor can take a few steps to limit damage and enhance the positive directions of discovery. All are based on having a good familiarity of what is available.</p>
|
||||
<ul>
|
||||
<li>1. Suggest specific sites with known quantities of good and accurate information--geared to the degree possible to the level and background of the student. Do not just give the student a general ham-link site. (Students will discover these sites fairly quickly.)</li>
|
||||
<li>2. Select specific URLs (web page addresses) within sites that take the student to the most relevant material. For example, at my own site-- devoted to antenna theory and practice--there are advanced articles that might not be informative to newcomers. However, there is also a series of articles designed for relative beginners, and one can directly access this series. (For example, <b><a href="../gup/groundup.html">Antennas From the Ground Up</a></b> leads directly to the while bypassing the main index page.)
|
||||
</li>
|
||||
<li>3. Encourage students to discuss with you what they have been reading on the web, and to give you the web site address. This offers you the opportunity to supplement the material, to help the student see its relevance and application, and to overcome errors and misinterpretations. The web materials should be only a start toward productive conversations.</li>
|
||||
<li>4. Offer the student additional or alternative web pages to investigate relative to those he or she brings to you.</li>
|
||||
<li>5. Relate the web site material directly to licensing and other classroom materials at hand to reinforce important ideas and concepts.</li>
|
||||
</ul>
|
||||
<p>Ultimately, the existence of general ham-link sites cannot be hidden. Therefore, it is better to approach them head-on, informing students of typical URLs. However, also offer guidelines for their use, lest the student get caught in a maze of links that interferes with the learning process. Show them how to extract useful information without printing everything in sight. Let them bring one or two key pieces of information to class for individual or group discussion. Help them to distinguish casual interesting reading from useful reference material. Reference material may not be just technical or regulatory information, but as well may include how hams live and operate around the world. This latter type of data can be useful when students make their first DX contacts.</p>
|
||||
<p>In short, teach students to be as selective in their web browsing and searches as you are.</p>
|
||||
<p><b>Lists, Chatrooms, and New Groups</b>: Whether in paper or on-line form, web sites are generally one-way instruments of teaching and learning--from the site to the student. Interaction is largely after the fact in the form of student-teacher or classroom discussion. When not in class, students often want to pose questions or share information. Lists, chatrooms, and news groups offer three different opportunities for doing so.</p>
|
||||
<p>Chatrooms are web creations for real-time conversations. News groups and distribution lists are e-mail creations that allow conversation on a somewhat slower basis, but still with less than a 1-day turn-around in most instances.</p>
|
||||
<p>Of the three conversational modes, the distribution list is, in my experience, the most productive for learning. Some lists are monitored, which means that inappropriate subject matter and behavior are detected and corrected. Some lists are moderated, so that inappropriate material is blocked from the list. These practices tend to reduce the occurrence of "flame wars" and other distractions from the main purposes of each list. Hence, the level of information transfer tends to be much higher than on other conversational modes.</p>
|
||||
<p>The means by which a student becomes part of a distribution list is by e-mail subscription to the "listserver" or the "majordomo" of the list. One list of special note is QRP-L, a list once based at the lehigh.edu site. Since the list has moved, it is used here only as a sample of procedures that may vary slightly from one list to another. QRP-L focused on QRP activities and construction and afford subscribers a chance to ask question and pass along news to other subscribers. It is one of the best places for relative beginners to HF operation to ask questions about equipment and antennas, although holding to the low-power focus is important as well. We may use this list as an example of how a distribution list works.</p>
|
||||
<p>In this example, the message data is shown in capital letters for clarity, although either upper or lower case will do in the real message. Sentence ending punctuation has been omitted so that it will not be confused with punctuation used within the addresses and message texts. To subscribe to this list, an individual sends a message to [email protected] using no subject line and only a simple text (here using my information as an example): SUBSCRIBE QRP-L LB CEBIK W4RNL</p>
|
||||
<p>The procedure might vary a bit from list to list, and some lists may have a confirmation procedure (to exclude commercial automated advertising systems from mass distributing advertisements on the list). Once subscribed, the individual should read carefully and keep at hand the welcome message, which will contain any procedural rules and limits to be observed. To send a message to the group, use the list address, in this case [email protected] The automated list server distributes a copy of the message to everyone who subscribes. On active lists, replies begin to emerge almost immediately. Some may go to the entire list. Others will come directly to the person who posed the question.</p>
|
||||
<p>Lists require special attention to courtesies, such as not simply including the original message in the reply message. That maneuver wastes reader time and mail-box space. Also important are staying within the subject area of the list and speaking respectfully in all messages.</p>
|
||||
<p>There are numerous special interest distribution lists, such as ANTENNAS and TENTEN-L. As the student refines his or her interests, other lists will become attractive as a place to be helped and to render help from one's own experiences, not to mention sharing both achievements and hard-won lessons.</p>
|
||||
<p>This very brief introduction to the teaching and learning opportunities available on the internet cannot do justice to what is available. Nor can this note cover all the points of guidance that an instructor should give to students in order to make their internet ventures both pleasant and productive. However, if the ideas here capture only a little bit of your attention and interest, then you may already be headed down a road of new opportunities in teaching the next generation of radio amateurs.</p>
|
||||
<center>
|
||||
<img src="../images/colorbar.gif" align="middle" width="540" height="4">
|
||||
</center>
|
||||
<p><i>From</i> Proceedings of the 1999 National ARRL Education Workshop<i>, (Newington: ARRL, 1999), pp. 76-80. © L. B. Cebik, W4RNL. Data may be used for personal purposes, but may not be reproduced for publication in print or any other medium without permission of the author.</i></p>
|
||||
<center>
|
||||
<img src="../images/colorbar.gif" align="middle" width="540" height="4">
|
||||
</center>
|
||||
<p><a href="edu.html"><img src="../images/return.gif" align="bottom" width="40" height="40"> Go to Educational Notes Index</a></p>
|
||||
<p><a href="../radio.html"><img src="../images/rtnhome.gif" align="bottom" width="40" height="40"> Return to Amateur Radio Page</a></p>
|
||||
<p class="topics-footer">Topics: <a href='../topics.html#education'>Education</a></p><br>
|
||||
</body>
|
||||
</html>
|
||||
Reference in New Issue
Block a user