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DIGEST OF ARTICLES - QST April, 1994 Following are digests of articles printed in the April, 1994 issue of QST. Such digests are being prepared for each issue of QST, and posted periodically. Subsequent issues will be posted one per week until they "catch up" to the current date in mid-1994, thereafter monthly. It is hoped that other hams will volunteer to post similar digests of the other ham technical publications such as QEX, CQ, 73, COMMUNICATIONS QUARTERLY, RTTY JOURNAL, et al. Especially desirable would be digests of publications in other countries, such as the RSGB RADIO COMMUNICA- TIONS and ham magazines in Europe, Japan, Australia, and other countries around the world. We English speakers would especially enjoy them if they were translated into our language, but they would also be valuable additions to the world's knowledge if they were posted in the language of origin. Who knows? Some bi-lingual ham somewhere might translate them into English and re-post them. Worldwide communications are getting better and better. The time has come to make the world's ham press available to all hams throughout the world! The major value of digests is to give readers sufficient information to decide whether to obtain a copy of the full text. If any U.S. reader wants a copy of an article in QST, please inquire of other hams in your own neighborhood. Many have collections of back issues. Anyone who is unsuccessful in finding a fellow ham with a collection should try every library in the area, especially those at universities and technical colleges. If all else fails, a copy can be obtained from the ARRL Technical Department, 225 Main St., Newington, CT 06111-1494 USA for a fee of $3.00 per copy. Remember, it is both cheaper and quicker to obtain one locally. Readers in most other countries can obtain copies from their own national ham organizations, sometimes translated into their own languages. -------------------------------CUT HERE--------------------------------- COPYRIGHT NOTICE: Copyright to all the following material from QST Magazine is held by the American Radio Relay League (ARRL), effective on the date of issue. Permission is granted for redistribution of the following in its entirety, or in part, provided that this copyright notice is not removed or altered and that proper attribution is made to ARRL as publisher of QST, to the authors of the original articles, and to W. E. "Van" Van Horne, W8UOF, author of this compilation. _________ TABLE OF CONTENTS (line number in parentheses - counting from CUT HERE line) TECHNICAL ARTICLES (TA) TA1:Build Your Own LOWFER Transceiver 75 TA2:The Trigonal HF Beam 125 TA3:A Function Generator with a Frequency-Counter Digital Readout 180 TA4:The RingMaster Ring Detector 221 TA5:The Elkhart County Tone Alert 262 PRODUCT REVIEW (PR) PR1:ICOM IC-707 MF/HF Transceiver 304 PR2:Solder-It Soldering Kit 369 PR3:Radioware SSTV Explorer 401 HINTS AND KINKS (HK) HK1:Adding a Noise Filter Can Be Worse Than No Filter At All 446 HK2:An RF Sniffer Meter 471 HK3:Curing RF Noise in a Fluorescent Shop Light 494 HK4:Speaker Connectors as Power Terminals 507 HK5:A Spinner for Kenwood Tuning Knobs 518 HK6:Using Computer Graphics for Equipment Construction and Repair 537 HK7:A Handy, Padded H-T Case 556 TECHNICAL CORRESPONDENCE (TC) TC1:Automatic Antenna Tuners for Wire Antennas 573 TC2:Sniff! Sniff! I Smell Line Noise! 616 LAB NOTES (LN) LN1:Where Am I? 638 NEW HAM COMPANION (NHC) NHC1:Packet Without Computers 675 NHC2:The Doctor is IN 701 NHC3:An INDESTRUCTIBLE Dipole for 10 Meters 717 NHC4:A Climatological Analysis of the Dayton HamVention 739 NHC5:The SWR Obsession 777 NHC6:Do I Need a Linear Amplifier? 803 RADIO TIPS (RT) RT1:The 10-Meter Band Plan 831 GENERAL INTEREST ARTICLES (GI) GI1:Operating Backpack Portable 857 GI2:Reading Radio Fiction 870 GI3:Digital Signal Processing: The Final Frontier 886 GI4:Electromagnetic Fields and Your Health 912 1162 ------------------------------------------------------------------------ TECHNICAL ARTICLES (TA) _________ Title>TA1:Build Your Own LOWFER Transceiver Author>Curry, David - WD4PLI Source>QST Apr 94, pp. 26-31 Abstract>Operating in the 1750-meter band which does not require a license. Power input is limited to 1.0 watt and the antenna must not exceed 15-meters in length (49-feet), including feeder. Range of up to 200 miles is possible. Includes construction information for a suitable transceiver. Digest>The subject of this article is the 1750-meter (160- to 190-kilohertz) band which is not, strictly speaking, an amateur band; it is open to all without the need of a license. Transmit input power is limited to 1-watt. In addition, the transmitting antenna is limited to a total of 15-meters (49-feet) in length, including the feedline. Mr. Curry indicates that almost any kind of an antenna will do if one wants to transmit no more than one mile (1.6 km). If "DX" operation (several, to as many as 200, miles) is desired, a resonant vertical antenna is necessary. He recommends a vertical made of aluminum tubing with a 12-foot (3.5 meter) diameter "top-hat". For resonance, a large diameter, multi-turn loading coil must be attached at the base and a minimum-length coax feedline should be tapped across the first few turns. The coil should be close-wound of number 18, or larger, enameled wire on a 6-inch (15-cm.) diameter form. The total number of turns should be determined by experimentation to establish resonance at the desired frequency. The author provides a schematic diagram and construction details for a complete transceiver, which he calls "Model 893". It uses 6 integrated circuits, including the voltage regulator; receiving-type variable capacitors, and several dozen other electronic parts, all readily available from sources listed in the article. He also recommends a low-pass filter for the input from the receiving antenna to minimize reception of noise and interference from strong broadcast band, and other local signals. On the 1750-meter band, common practice is not to use full amateur call signs. Three- or four-letter combinations are usually adopted; many hams use the first and last two or three letters of their calls. A kit of all parts except the enclosure and knobs is being offered by the author for a price of $94.00, including USA shipping. With the kit comes a manual detailing the construction, and also information about antennas, and operating hints. For further general information, he suggests that interested parties might want to join the Longwave Club of America, 45 Wildflower Road, Levittown, PA 19057. _________ Title>TA2:A Trigonal HF Beam Author>Bird, Dick - G4ZU/F6IDC Source>QST Apr 94, pp. 34 Abstract>Describes a switchable beam antenna made of wire. It is comprised of 3 dipoles with a common parasitic reflector behind them. The radiation pattern has 3 switchable lobes, 120-degrees apart. Digest>In this article, Mr. Bird shows the construction of a switchable beam antenna made of three dipoles aligned as the legs of an equilateral triangle, with a common reflector behind all three. The beam is switchable to three different directions, spaced 120-degrees apart around the azimuth. To understand the arrangement of the wires, it is necessary to draw an equilateral triangle. Then, from each apex toward the mid-point of the opposite side, draw a line. If done properly, the three lines will meet at a common point at the center of the triangle. Of each of the lines just drawn, erase the portion between the common center point and the center of the respective side. Now, three lines join at each apex of the triangle. Draw an insulator in each of the three lines close to, but not touching, the apex. Also draw an insulator in the center of each side of the triangle. The drawing of the plan view of the antenna is now complete. Feeders lead to each of the three center insulators in the sides, representing the dipoles. The "Y" made up of the three wires that join at the center is the "trigonal" reflector which directs the beam of each of the three dipoles, whichever is excited. On the 20 meter band, the author used a dimension of 33-feet (10.06-meters) for each dipole; each leg of the "Y" was 17-feet, 10-inches (5.44-meters), measured from the center to the insulator; the total distance from the center point of the triangle to each apex is 19-feet (5.79-meters). Those dimensions, in feet, can be calculated for any frequency by dividing a number (N) by the frequency in MHz, as follows: For the length of the dipole, N=468 For the length of each reflector arm, N=252.7 For the total distance from center point to apex, N=269.1 To convert feet to meters: 1-foot = 0.3048 meters. Accompanying the article is a plot of the radiation pattern of the antenna on 20-meters when it is mounted 25-feet (7.6-meters) above average ground. It shows a rounded cardioid pattern with good directivity and excellent front-to-back ratio. The author reports that he built such an antenna that showed a measured forward gain of nearly 9 dBi and a FB ratio of more than 34 dB. The antenna analysis performed using "Elnec" antenna software indicates about the same amount of forward gain, but a FB ratio of between 22- and 25-dB, which is still quite respectable for even a 3-element Yagi although this is only a 2-element design. _________ Title>TA3:A Function Generator With a Frequency-Counter Digital Readout Author>Spencer, Ben C. - G4YNM Source>QST Apr 94, pp. 35-39 Abstract>Construction of an audio-frequency function generator with integral frequency counter. Functions available are sine, square, and triangular waves. Digest>One of the most important items of bench test equipment required on an experimenter's workbench is an audio-range function generator capable of generating signals of various waveshapes, including especially sine and square waves. Mr. Spencer has designed and built a versatile unit capable of generating those two, plus triangular waves, over a frequency range of 10-Hz. to 80-KHz. For sine and triangular waves, the range extends to 100-KHz. The function generator circuit itself is contained in a single integrated circuit. In addition, a dual op-amp chip contains the remainder of the active elements. The addition of a couple dozen resistors, a few capacitors, and some switches completes the entire instrument. The frequency counter is contained on a separate PC-board and uses 6 decade-counter chips, 3 dual-digit LED displays, and a few other components. The power supply is built on a third PC-board, and produces +12 and -12 volts regulated output. The author estimates that a constructor can probably duplicate the unit for a total cost of $50, including enclosure. Final adjustment requires a voltmeter and an oscilloscope. The article includes full instructions. No complete kit of parts for this project is available, although a set of three PC-boards, etched and drilled can be obtained from FAR Circuits, 18N640 Field Court, Dundee, IL 60118-9269. The price is $17.50, including domestic shipping. A PC-board template package is available from the ARRL for an SASE. Address the request to Spencer Function Generator Template, Technical Department Secretary, 225 Main Street, Newington, CT 06111. _________ Title>TA4:The RingMaster Author>Rumbolt, Robin - WA4TEM Source>QST Apr 94, pp. 40-42 Abstract>The advent of "Caller ID" by telephone companies defeats private repeaters' secret telephone numbers. Described is a device that uses the "RingMaster " (TM) service, also available from phone companies, to restore privacy to the private repeaters. Digest>The device described by this article was designed to overcome a severe problem that was occasioned by the introduction, in some areas, of "caller ID" by the telephone companies. Caller ID allows anyone who subscribes to the service to be able to see the phone number of the telephone where the incoming call originates. This seemed to represent a disaster for repeater operators who use secret phone numbers known only by members of the club supporting it. In its basic form, it would seem to allow anyone with a Caller ID display to make autopatch calls to themselves and see the repeater phone number. In some areas, Caller ID can be blocked by using certain call sequencing, but in the author's area, this is not allowed. What is allowed is a "RingMaster" (TM) service. This allows several telephone numbers to be assigned to one phone line. The ring timing differs depending upon the number used to call. Dialing the main number causes the phone to ring in the normal "2-seconds ON, 4-seconds OFF" sequence. With the three special RingMaster numbers, there are two additional special sequences. The author has designed an electronic circuit that is programmed to answer only a ring using one of the special sequences, specifically sequence No. 1, which is "0.8-seconds ON, 0.4-seconds OFF", repeated continuously. If a would-be hacker should place a call to himself, the Caller ID would display the main number of the repeater, but not the special number. The repeater would not respond to the main number. The circuit is assembled on a single PC-board. The input is electrically isolated from the phone line by an optoisolator and logic devices detect the proper sequence, which closes a relay that connects the phone line to the autopatch. _________ Title>TA5:The Elkhart County Tone Alert Author>Drudge, Dennis A. - W9XD Source>QST Apr 94, pp. 43-46 Abstract>Construction of an alarm system to operate in conjunction with an amateur repeater to provide tone-alert alarms of severe-weather situations. Digest>In Elkhart County, northern Indiana, the organization that maintains the repeater decided to develop a tone-alert system to notify all members of severe-weather situations as they develop. They designed a very effective system which included the design of an alarm that all members were encouraged to build. Mr. Drudge describes the system and gives construction information in this article. The system, in operation, responds to either of two 3-digit DTMF sequences, and also the Long Tone Zero (LiTZ) signal. The latter is a 3-second zero tone used as a universal distress call on repeaters, with the endorsement of the ARRL. When actuated, the system sounds an alarm for 5-seconds, switches the received audio to a speaker, and starts an LED blinking. A circuit diagram is included in the article. The logic is embodied in nine ICs plus a voltage regulator. They include a DTMF decoder chip, a 4- to 16-line decoder, and several logic chips. All parts required to build the unit are readily available from a number of sources, several of which are listed by the author. He makes available a "partial kit", made up of a PC-board, a DTMF chip, and a latching relay for $30.00, including domestic shipping. He estimates that the total cost of a unit, including a case, should be less than $50.00 For those who want to do the whole job themselves, a template package containing the double-sided PC-board pattern and parts overlay can be obtained from the ARRL Technical Department Secretary, 225 Main Street, Newington, CT 06111. Enclose a business-size SASE and request the Elkhart County Tone Alert System PC-Board Template. ------------------------------------------------------------------------ PRODUCT REVIEW (PR) Conductor: Mark Wilson - AA2Z Editor, QST _________ Title>PR1:ICOM IC-707 MF/HF Transceiver Author>Ford, Steve - WB8IMY Source>QST Apr 94, pp. 75-78 Abstract>Performance review of ICOM's latest "entry-level" MF/HF transceiver. Digest>This transceiver is ICOM's answer to the low-priced "entry-level" rigs that are now coming onto the market. It is a small unit that provides most of the functions that even the most sophisticated modern ones offer. However, to establish a low price, some functions must be omitted, and the reviewer discusses several. The front panel is free of much of the clutter common on larger units, but all the essentials are there. There is a large Power rocker switch; also a very large and well-designed tuning knob, an RIT knob, an AF Gain/Squelch knob, and two tiny knobs for mike gain and r.f. power, respectively. Seven switches are to the left of the tuning knob: Tuner, RIT, Tuning Speed, Preamp/Attenuator, Mode, Noise Blanker, and Scan. The Mode switch steps through CW, USB, LSB, AM, and FM. On the right side of the tuning knob are four push-buttons that control the dual VFO and Memory functions. The unit is well designed for mobile use; unique in its class, it has a speaker on the front panel facing the driver of an automobile. Jacks on the back panel are available to make connections for operating in digital modes, and also to drive an amplifier. The reviewer pointed out a number of limitations, some of which are serious. Especially in CW operations, there are a number of annoying features. One is the AGC; it is set either "Fast" or "Slow", and the settings cannot be adjusted. In "Fast", the attack is so slow that it makes moderate to strong signals annoying. Also, the CW tone is set at a fixed 800 Hertz, which is uncomfortably high for many experienced operators. Digital modes are received in the SSB setting and the lack of narrow i.f. filtering is "painfully evident". The reviewer states that the manual suggests a "workaround" method of using the CW i.f. filter for digital operations, but it is clumsy, at best. In SSB operation, the reviewer missed having a VOX function. The most glaring omission for the reviewer was the lack of a manually-operated transmitter switch. For a ham who uses a manual antenna tuner, it is necessary to switch the rig into continuous transmit mode while adjusting the tuner. In absence of such a switch on the front panel, the operator has to use the microphone push-to-talk switch, or hold the CW key down, while tuning. In all other aspects of transmitting, the rig performed very well, indeed. Its frequency control is extremely stable, even from a cold startup. All reports on the quality of the audio were good to excellent. The performance of the receiver was found to be good in testing. The noise floor, with a 500-Hz. i.f. filter in use, was between -120 dBm. and -138 dBm., depending upon frequency band in use. Dynamic range was 111 dB. to 128 dB.; 2-tone third-order IMD dynamic range was from 90 dB. to 87 dB. To summarize, the reviewer said: "The IC-707 provides good basic radio performance for new hams and veterans alike, on a budget." The manufacturer's list price for the IC-707 is $1032, without power supply, antenna tuner, or any other optional features. _________ Title>PR2:Solder-It Soldering Kit Author>Gruber, Mike - WA1SVF Source>QST Apr 94, pp. 78-79 Abstract>A kit allowing anyone to solder together many different combinations of metals, including aluminum, stainless steel, and zinc. Digest>This soldering kit is made up of a small butane torch and a collection of solder-paste syringes. The syringes are like hypodermic needles and each contains a paste made of soldering flux mixed with powdered solder. Each is designed for a different metal or combination of metals. To tin or solder, one spreads the paste on the surface to be wetted and heats it with the torch. First, the flux, then the particles of solder, melt and bond to the work piece. Four different pastes are supplied. The Aluminum paste is, perhaps, of most interest to amateurs because of the great difficulty of soldering aluminum. The reviewer found that he had good results soldering aluminum to aluminum, and also soldering aluminum to other metals such as brass. He found that he had to clean the surfaces to be soldered very thoroughly, using steel wool. He advises some practice on test pieces before undertaking a critical soldering job. In summary, the reviewer was impressed and found that the kit enables one easily to solder "an unbelievably wide range of metals". The manufacturer is Solder-It, Box 20100, Cleveland, Ohio 44120. The list retail price for the soldering kit is 59.00. Replacement syringes are $6.00 each and a variety of tip attachments are also available. _________ Title>PR3:Radioware SSTV Explorer Author>Pagel, Paul - N1FB Source>QST Apr 94, pp. 80-81 Abstract>Describes a hardware/software package that allows any amateur with a transceiver and computer to receive SSTV. Digest>The Radioware SSTV Explorer is a hardware/software package that allows anyone with an HF receiver and DOS computer to receive SSTV images. Nothing else is required! The package is made up of a floppy disk (either 3.5- or 5.25-inch size), and a 60-inch cable. The cable is terminated with a DB-25 connector on one end and a 1/8-inch diameter, 2-conductor audio plug on the other. The DB-25 attaches to the computer's RS-232 serial port; the audio plug to the audio output of the receiver. That, plus a 27-page instruction manual, is all there is to it; the only electronic hardware required is on a tiny PC-board that is inside the DB-25 connector! For good results, the computer should contain a VGA display board able to display at least 32,000 colors, and also a one-megabyte, or more, of video memory. Anyone equipped with that will be able to receive the full range of SSTV images now being transmitted on the HF bands. The software is quite complete and allows one to receive, display, and save on disk, any images received. The reviewer found the manual to be quite complete in giving full instructions concerning the use of the software. It enables one not only to capture and save the SSTV images, but also allows them to be edited. After they have been received, one can invert, mirror, rotate in 90-degree increments, zoom, remove all color, filter, and otherwise manipulate the images. The manual does not, however, contain any technical description of the hardware or software, an omission that the reviewer regretted. The manufacturer is Radioware, 225 Stedman Street, No. 27, Lowell, MA 01851. The list price is about $50.00. ------------------------------------------------------------------------ HINTS AND KINKS (HK) Conductor: David Newkirk - WJ1Z Sr. Asst. Technical Editor _________ Title>HK1:Adding a Noise Filter Can Be Worse Than No Filter At All Author>Shelhamer, Mark - WA3YNO Source>QST Apr 94, p. 82 Abstract>Describes a condition in which a noise filter inserted in the d.c. power leads, rather than eliminating it, actually causes an increase of electrical noise in a car. Digest>The author relates that he had problems with electrical noise in his automobile AM/FM radio and, to try to eliminate it, he installed a commercial noise filter in the d.c. power leads. The result was a negligible improvement. Upon investigation, he found that the shield of the antenna coax was attached to the radio chassis ground at one end, and to the frame of the car at the other. He realized that the commercial filter blocks r.f. from flowing on either the positive or negative d.c. power leads. Hence, noise that otherwise would have been grounded through the negative d.c. lead was blocked and flowed through the coax shield instead. This, then, was capacitively coupled to the center conductor, and so to the antenna input of the radio. When he removed the commercial filter and grounded the receiver ground directly to the negative battery terminal, the noise was greatly reduced. _________ Title>HK2:An R.F. Sniffer Meter Author>Hoyt, Emerson - WX7E Source>QST Apr 94, p. 82 Abstract>Describes a very simple but sensitive meter to detect the presence of r.f. energy in circuits. Digest>Mr. Hoyt provides a schematic diagram, and also description, of a meter that he has used to detect the present of r.f. in circuits of all kinds, including antennas. It is built from a small microammeter with a germanium diode (1N34, or similar) attached to each meter terminal. The diodes are installed with polarity such that, if any current flows, it will tend to drive the meter upscale. He attaches a length of No. 18 bus wire, about 2-inches long, to the free ends of both diodes, then twists them and solders them together at the outer end to form a probe. He slips a piece of insulating tubing over the leads, leaving only the tip exposed. He finds that this meter is a very sensitive detector of r.f. of any frequency. _________ Title>HK3:Curing R.F. Noise in a Fluorescent Shop Light Author>Lee, Mitchell - KB6FPW Source>QST Apr 94, p. 82 Abstract>A bypass capacitor cures noise from a fluorescent light. Digest>Mr. Lee found that a new shop light in his home caused tremendous noise that appeared on all HF bands from 160-meters, up. He eliminated almost all the noise by bridging a 0.22-mfd. metallized-film capacitor, rated for use on 125-volt a.c., across the power lines at the point where the cord enters the fixture. _________ Title>HK4:Speaker Connectors as Power Terminals Author>Bauer, Jeff - WA1MBK Source>QST Apr 94, p. 82 Abstract>Speaker connectors can be used as d.c. power connectors. Digest>Spring-loaded speaker terminals were noted in Hints and Kinks, December, 1987, as good for plugging in crystals. Mr. Bauer also finds them useful as light- to medium-duty d.c. connectors. _________ Title>HK5:A Spinner for Kenwood Tuning Knobs Author>Nollet, Kenneth E. - K0EN Source>QST Apr 94, pp. 82-83 Abstract>How a bent wire can convert a standard Kenwood transceiver knob into a spinner-knob. Digest>The author uses a Kenwood transceiver, yet likes the type of tuning knob used on ICOM gear, among others, that provides a shallow hole in the face of the knob into which the operator can poke a finger and use it as a spinner. He fashioned a comparable spinner out of a piece of plastic-coated, heavy-gauge aluminum wire. He bent the wire into a small circle to act as a finger hole, then extended the length just far enough that it could be bent over the edge of the knob as far as the set-screw hole, and stuck it into that hole. When he bent the wire to form a snug fit over the knob, it held itself in place and acted as an effective substitute for the hole cut into the knob itself. _________ Title>HK6:Using Computer Graphics for Equipment Construction and Repair Author>Whitsitt, Ronald V. - N5JSC Source>QST Apr 94, p. 83 Abstract>Using common computer software to prepare labels for "homebrew" projects. Digest>Applying printed labels to the face of "homebrew" projects is always a problem. Mr Whitsitt gets good results using his computer and a laser printer to print appropriate labels on paper, He states that almost any "paint" program running on a PC will be able to print lettering, as well as arcs for meter scales, etc., to form attractive labels. After the label is printed on paper, he covers the paper with Scotch Magic Tape (TM). Then he cuts it to size with a hobby knife and glues it onto the equipment using rubber cement. _________ Title>HK7:A Handy, Padded H-T Case Author>Norman, Nona M. - N8CKS Source>QST Apr 94, p. 83 Abstract>A padded oven mitt works well as a case for an H-T. Digest>Ms. Norman needed a padded holder for carrying an H-T in her briefcase. She discovered that a padded oven mitt, commonly sold in houseware stores, can be used as is, or else trimmed to shape and resewn, to do the job. For sewing, turn the mitt inside out, sew the edges around the desired shape, and trim off the excess. ------------------------------------------------------------------------ TECHNICAL CORRESPONDENCE (TC) Conductor: Paul Pagel - N1FB Associate Technical Editor _________ Title>TC1:Automatic Antenna Tuners for Wire Antennas Author>Belrose, John S. (Jack) - VE2CV Source>QST Apr 94, p. 84 Abstract>Even though an antenna tuner may be able to tune a short whip to resonance at a low frequency, it will not be an efficient antenna. A high-Q, base-mounted loading coil will be much better. Digest>This letter is a commentary on the article by Jeff Bauer, WA1MBK, reviewing the SGC, Inc. "Smartuner" automatic antenna system tuning unit (ASTU) in QST Nov 93. In it, Mr. Bauer noted that he was able to tune a 15-foot piece of wire on 160-meters and expressed the opinion that as little as 8-feet of wire could be used for frequencies above 3.3-MHz., "making a 102-inch CB mobile antenna More Than Sufficient for multi-band mobile use". In this letter, Mr. Belrose points out that such an antenna would be extremely inefficient, largely due to losses in the ASTU itself. He reports a series of tests which show a graph of the effective output vs. frequency over a range of 2- to 13-MHz. for a 20-foot whip antenna used in two different configurations. The first configuration is with a large, high-Q, base-loading coil, and the other is with the same antenna mounted on a boat with an ASTU inside the cabin. A third antenna, a small diameter transmitting loop, is also plotted for reference. The report shows that the 20-foot whip with a proper base-loading coil will deliver a signal only about 4-dB. below that of an isotropic radiator. The same whip operated with an inside ASTU, on the other hand, produces a signal that is more than 15-dB. below isotropic. When he scales the results to estimate the performance of a 102-inch CB mobile antenna on 80-meters, he finds the result to be off the scale of the graph at a level of more than 20-dB. poorer than isotropic. The curve for the small transmitting loop shows performance between the two configurations of the 20-foot whip. Mr. Belrose also shows that any capacitance to ground in the antenna circuit between the ASTU and the radiator, itself, is a source of substantial loss of signal. Even the capacitance across a feedthrough insulator and a base-mounting insulator loses considerable power if it is between the tuner and the radiator. Only when the loading coil is a part of the radiator, itself, are those losses eliminated. _________ Title>TC2:Sniff! Sniff! I Smell Line Noise! Author>Thorington, Lloyd - N0RQU Source>QST Apr 94, p. 85 Abstract>Describes a hand-held Yagi antenna used for locating the source of line noises. Digest>This letter describes a portable 3-element Yagi antenna built by the author for use in locating the source of line noises of various types. It is designed to operate at about 130-MHz. It is constructed of a piece of wood with 3 commercial "rabbit ears" TV antennas, spaced appropriately as the driven element, reflector, and director of a 3-element Yagi. The elements collapse against the stick for carrying, but when opened up, very effectively identify the source of arcing atop poles, or other noise-makers on power lines. ------------------------------------------------------------------------ LAB NOTES (LN) Conductor: Steve Ford - WB8IMY Asst. Technical Editor _________ Title>LN1:Where Am I? Author>Gruber, Mike - WA1SVF Source>QST Apr 94, pp. 86-88 Abstract>Description of Latitude/Longitude and grid locator position- measuring systems. Digest>This article is written in the form of questions and answers. It is a fictitious conversation between a ham asking questions and an unnamed authority providing the answers. It explains how the earth is divided by latitude and longitude designations, and also by the world grid locator system. The world of ham radio was divided into "grid squares" of the Maidenhead Locator System at a meeting of hams in 1980. Each grid square is one degree of latitude by two degrees of longitude. Grid squares are indicated by two letters, dubbed the "field", and two numbers, called the "square". The squares are further divided into subsquares by the addition of two letters after the grid square. The subsquares measure 2.5-minutes of latitude by 5-minutes of longitude. Various ARRL publications and computer programs allow one to find the grid square and subsquare for any location in the USA. Very precise maps of the entire United States, which include elevation above sea level as well as geographic features down to individual houses, in some cases, are published by the U.S. Geological Survey (USGS). They are called Topographical Maps and can be obtained from the USGS Map Distribution, Bldg. 810, Box 25286/Denver Federal Center, Denver, Colorado 80225. They can also be found, along with an index, in many public libraries. ------------------------------------------------------------------------ NEW HAM COMPANION (NHC) The New Ham Companion is a regular section of QST. It features articles of primary interest to newcomers to the hobby. _________ Title>NHC1:Packet Without Computers Author>Wolf, Fred - N3CSL Source>QST Apr 94, pp. 64-65 Abstract>Using a "dumb terminal" for packet operation, instead of a computer. Digest>This article points out that a computer is not an essential part of a station that can communicate via the packet mode. It is entirely possible to operate a packet station with a "dumb terminal" instead of a computer. Very large numbers of terminals were built and used to communicate with central computers in office settings before personal computers (PCs) became common on most desks. Many are now surplus and available for low prices. The author describes an amateur packet station using a terminal, a terminal node controller (TNC), and an amateur transceiver. The transceiver can even be an H-T. A station so equipped will be able to send and receive packet messages as well as any. There are certain other desirable functions, however, that require a computer. Among them are recording, editing, and manipulating the text, driving a printer to print the messages on paper, and others. _________ Title>NHC2:The Doctor is IN Author>Various Source>QST Apr 94, p. 66 Abstract>Questions and answers of interest to newcomers. Digest>The questions discussed this month include: how to obtain copies of obsolete software that the manufacturer no longer supports; the proper length of a 2-meter whip antenna; frequencies within a band on which it is legal to operate CW; use of foreign languages by American amateurs on radio; the fact that it is not legal to transmit amateur radio from a commercial airliner; problems in computer operation when a new board was plugged in; and how to use a Commodore 64 computer on packet mode. _________ Title>NHC3:An Indestructable Dipole for 10-Meters Author>Bowles, Chester S. - AA1EX Source>QST Apr 94, p. 67-68 Abstract>Construction of a simple and inexpensive 10-meter antenna. Digest>This article is meant to demonstrate how simple it is to build an antenna for 10-meters. The author shows photographs and describes a dipole that he built using 1/2-inch (12-mm.) galvanized steel electrical conduit, a wooden dowel for an insulator, and hose clamps to attach the two conductors of the coax cable feedline. He supports the antenna by attaching it directly to wooden supports, without insulators. Presumably, he only operates it in dry weather! In a sidebar, Steve Ford - WB8IMY, points out that the 10-meter band is not completely dead, even though sunspot activity is approaching the minimum. He advises that anyone interested should scan the band, especially from late morning through early afternoon hours. Even at the bottom of the sunspot cycle, there will be sometimes when contacts are possible on the band, even DX. _________ Title>NHC4:A Climatological Analysis of the Dayton HamVention Author>Friedman, Neil D. - N3DF Source>QST Apr 94, p. 69 Abstract>Weather conditions at Dayton HamVentions are almost always bad! Digest>The Dayton HamVention is the world's largest gathering of hams and is held yearly in Dayton, Ohio, at the end of April. Many thousands of hams come from all over the world to view the exhibits of equipment, which are held inside arena buildings, and also to browse the enormous flea market which occupies every space of the large parking lots that surround the facility. Because the paved parking lots are entirely occupied, many visitors park in temporary "lots" in the surrounding area that are actually open fields. Year-after-year, visitors have come to realize that the weather conditions in Ohio in late spring are characterised by wide swings in temperature and frequent rainfall, often heavy. Old-timers tell many tales of parking lots that turned to seas of mud, stranding many cars; drenching rainfall accompanied by winds that blew down canopies and tents; and of other such calamities. The author has made a study of the climatological records and presents bargraphs showing the range of temperatures and the frequency of rainfall for each day of every HamVention that has been held for the past 20 years. His information shows that in only four years of the twenty did no rain fall during any of the three days. In only one year did rain fall all three days; but rain fell in two out of the three days about one-third of the years and at least on one day in the rest. Temperatures have ranged from 30 degrees F. (-1 degree C.) to almost 90 degrees F. (33 degrees C.). The author presents the information without stating any conclusions except that he intends again to be present this year, and that he plans to have with him clothing suitable for almost any conceivable weather condition. _________ Title>NHC5:The SWR Obsession Author>Ford, Steve - WB8IMY Source>QST Apr 94, pp. 70-72, 74 Abstract>There is no value in reducing SWR below certain levels, depending on frequency and type of feedline. Digest>In this article, the author attempts to put Standing Wave Ratio (SWR) in proper perspective; and also to compare the two basic kinds of feedlines in common use: open-wire and coaxial cable. Many hams make a fetish of obtaining SWR as close as possible to an exact 1:1. Usually it is a waste of time to struggle to lower an SWR much below 2:1 because the reduction of energy loss in the feedline to be accomplished would make a negligible difference in the perceived signal strength at the remote receiver. The author gives five hypothetical examples to illustrate typical examples of performance. All show that antennas fed with coax perform poorly when the SWR is high, even at HF; and that VHF/UHF antennas show severe losses with long runs of coax, even with low SWR. Open-wire lines, on the other hand, provide high efficiency with either long runs or high SWR, or both. _________ Title>NHC6:Do I Need a Linear Amplifier? Author>Aurick, Lee - W1SE Source>QST Apr 94, pp. 73-74 Abstract>Do not spend money on an amplifier until every other means of improving signal strength has been used. Digest>In this article the author takes a hard look at the benefits, versus the cost, of a linear amplifier in a hamshack. If an existing station radiates 100-watts, an amplifier can be added to boost that power to from 400-watts up to the 1500-watt legal maximum. If, in a given QSO, one receives a signal report of S-7, boosting the power to 400-watts would raise the strength to about S-8; going to the full legal limit would raise it to S-9. The cost of a 400- or 500-watt amplifier (new) would be of the order of $800 to $1500. To go to 1500-watts, the cost would be $2500 to $5000. Individual hams must make up their own minds concerning whether the benefits to be obtained are worth the cost. No ham should commit to an expensive amplifier until other means of increasing signal strength, such as better antennas, have been thoroughly considered. ------------------------------------------------------------------------ RADIO TIPS (RT) These are short items, scattered among the articles in the NEW HAM COMPANION section. _________ RT1:The 10-Meter Band Plan Author: Anonymous Source: QST Apr 94, p. 68 Abstract: Recommended frequency allocations. Digest: Frequency Service 28.000-28.070 CW 28.070-28.150 Digital modes 28.150-28.190 CW 28.190-28.200 New beacon subband 28.200-28.300 Old beacon subband 28.300-29.300 Phone 29.300-29.590 Satellites 29.600 FM Simplex 29.610-29.690 FM repeater outputs FM Repeater Pairs: (input/output) 29.520/29.620 29.540/29.640 29.560/29.660 29.580/29.680 ------------------------------------------------------------------------ GENERAL INTEREST ARTICLES (GI) _________ Title>GI1:Operating Backpack Portable Author>Andera, Jim - WB0KRX and Sample, Bill - N0IET Source>QST Apr 94, pp. 21-25 Abstract>The pleasures of taking radio gear along on hikes and climbs. Digest>The two authors are midwesterners and enthusiastic outdoorsmen, fishermen, hikers, and campers. They are also hams and enjoy taking radio gear with them on their backpacking hikes through the hills and mountains of the midwest and west. _________ Title>GI2:Reading Radio Fiction Author>Lisle, Larry - K9KZT Source>QST Apr 94, pp. 51-53 Abstract>A brief review of fiction written about radio operations. Digest>This is a description of some of the fiction that has been published about radio, or people involved in radio, down through the years. The author states that it was largely fiction that kept him interested while learning the rudiments of radio when he was young. He concludes by suggesting that any radio club that has a program for newcomers, especially teenagers, might well include some fiction to excite their interest. _________ Title>GI3:Digital Signal Processing: The Final Frontier Author>Moseley, Robin - WA3T Source>QST Apr 94, pp. 54-55. Abstract>April Fool's Day fiction. Digest>Many years ago, every April issue of QST contained an article written by the "famous inventor", Larson E. Rapp (pronounced: Larceny Rap). Each of these was a description of a new "invention" which started out as a reasonably credible statement of fact and observation. As the story went along, it became more and more unlikely until it finally ended with a preposterous mechanism or circuit that performed miraculous things, often repealing the laws of Physics. This was QST's way of celebrating April Fools' Day! The present article describes the use of digital signal processing (DSP), along with electronic neural networks, to build a machine that would take a skull, such as one from an archaeological dig, analyze the acoustic resonances in the bone, and use them to calculate what the actual face looked like when the skull was covered with flesh and skin. There is no editorial comment that indicates whether the author, Mr. Moseley, is related to Larson Rapp. But whether or not he is of the same blood line, it is certain that he follows in the same tradition. _________ Title>GI4:Electromagnetic Fields and Your Health Author>Overbeck, Wayne - N6NB Source>QST Apr 94, pp. 56-59 Abstract>Whether or not fears of damage to humans from radio waves are valid, take reasonable precautions to avoid excessive exposure. ------------------------------------------------------------------------ wvanho@infinet.com