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DIGEST OF ARTICLES -- QST, November, 1993 Following are digests of articles printed in the November, 1993 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:A 13.8V, 5-A Regulated Power Supply (83) TA2:A Low-Voltage Disconnect (111) TA3:A Simple, Two-Tone Audio Generator (146) TA4:An Update on Compact Transmitting Loops (166) TA5:Under the Hood II: Resistors (253) TA6:An Accurate Dip Meter Using the MFJ-249 SWR Analyzer (278) PRODUCT REVIEW (PR) PR1:MFJ-249 and MFJ-207 SWR Analyzers (362) PR2:Tejas RF Technology Backpacker II Model TRFT-550 Single-Band (436) CW Transceiver PR3:SGC Inc. Model SG-230 "Smartuner" Automatic Antenna Tuner (466) HINTS AND KINKS (HK) HK1:Ten-Minute ID Timer Revisited (504) HK2:Curing Multi-Mode Communications Processor Distortion With the (521) Kenwood TS-850S HK3:How to Connect an ICOM SM-8 Mike to the Yaesu FT-990 (537) Transceiver HK4:Inductance of Small Coils Wound on Machine Screws (552) HK4:Keep Your QST Binders in Shape (584) TECHNICAL CORRESPONDENCE (TC) TC1:Yaesu FT-990 Computer-Control Interface (600) TC2:No Ions in the Cold, Cold Ground (616) TC3:Small Antenna Efficiency (630) TC4:More on "Hands-Off" Mobile Operation (664) FEEDBACK (FB) FB1:"A Unified Approach to the Design of Crystal Ladder Filters" (677) QST May, 1982 THE NEW HAM COMPANION (NHC) NHC1:Remedial Radio (694) NHC2:Trouble-Shooting Your Radio Equipment (708) NHC3:The Doctor is IN (739) NHC4:The ARRL Wants YOU! (755) NHC5:You Have a Date With Oscar 21 (766) NHC6:I Wonder If... (779) RADIO TIPS (RT) RT1:D.C. Power Supplies (798) GENERAL INTEREST ARTICLES (GI) GI1:Amateur Radio Aboard Space Shuttles (811) GI2:Hello Again, to an Old Friend (832) GI3:The Coming of the Law (852) GI4:Solder to Talk (871) GI5:Hamming on the "Sunny Side of the Alps" (886) GI6:The Australian Connection (917) GI7:Sweepstakes Shack on Wheels (930) GI8:Satellites and Field Day (982) GI9:How Does a Section Manager Spend Field Day? (1004) ------------------------------------------------------------------------ TECHNICAL ARTICLES (TA) Title>TA1:A 13.8-V, 5-A Regulated Power Supply Author>Spencer, Ben - G4YNM Source>QST Nov 93, pp. 27-29 Abstract>Design and construction of a power supply for a transceiver, containing protection against shorts, overload, and overvoltage. It is built with inexpensive and/or surplus components from sources identified in the article. Digest>Mr. Spencer has designed and built a 13.8-volt power supply with a current capacity of 5-amps. In it, he has built protection against damage from short-circuits, time-dependent overload, and overvoltage. Thus he has designed it to be safe against almost all of the common causes of damage to either the supply or the equipment it powers. Yet he has tried to make it inexpensive by utilizing inexpensive and/or surplus components. In this article, the author gives full construction details. He includes wiring diagrams, parts placement information, and recommended sources of low-cost surplus parts for some of the key components. He uses the unit to power a 25-watt transmitter that continuously draws 4.5 amps. With that load, the heat-sink on which the regulator component is mounted gets very hot, but this is within design specifications. The supply has proven to be reliable and performs its functions well. _________ Title>TA2:A Low-Voltage Disconnect Author>Bryce, Michael - WB8VGE Source>QST Nov 93, pp. 31-34 Abstract>Design and construction of a circuit that protects a battery from damage caused by excessive discharge. A low-voltage disconnect (LVD) protects a battery, or its load, from damage that might occur when the battery discharges until its output voltage drops to a very low level, or zero. Mr. Bryce has designed and built such a circuit and has written this construction article so that readers may duplicate it. The unit measures the battery voltage continuously and opens the supply circuit when the voltage drops below a pre-set level. The voltage must rise to a higher pre-set value before power can be turned back on. The circuit uses IC op-amps and CMOS gates in conventional comparator and logic circuits. The output transistor, which provides operating current to the coil of a relay, is a Darlington integrated circuit. Although the relay contacts can be used to control either a.c. or d.c. loads, the author suggests that if it it is to be used to switch 120-volt a.c., the main relay should be mounted in a separate enclosure. A complete kit of parts is available from SunLight Energy Systems, 2225 Mayflower NW, Massilon, OH 44647 for a price of $58.00, including domestic shipping. A PC-board only is available from FAR Circuits, 18N640 Field Ct., Dundee, IL 60118-9269, for a price of $13.50, including domestic shipping. A PC-board template package is available from the ARRL Technical Department Secretary, 225 Main St., Newington, CT 06111 for a business-size SASE. Address the request to "Low Voltage Disconnect Template". _________ Title>TA3:A Simple, Two-Tone Audio Generator Author>Lee, James G. - W6VAT Source>QST Nov 93, pp. 35-36 Abstract>Instructions for constructing an audio generator. Digest>An audio generator is a useful item to have around a shack for SSB transmitter testing, or other audio experimenting and adjusting. Mr. Lee presents construction information for a very simple and inexpensive two-tone generator. The circuit is made up of two JFET Hartley oscillators that feed into a single output amplifier stage. The frequency of each oscillator is adjustable; one is normally adjusted to 600-Hz. and the other to 2100 Hz. There is no "magic" to those frequencies, but they provide a convenient pair of high- and low-tones that are not harmonically related. A selector switch is provided to switch on one channel, the other channel, or both, at will. _________ Title>TA4:An Update on Compact Transmitting Loops Author>Belrose, John S. (Jack) - VE2CV Source>QST Nov 93, pp. 37-40 Abstract>A report on computer studies, verified by field tests, of radiation patterns from small transmitting loop antennas. Results show that such antennas, when carefully made, can be useful and fairly efficient radiators, but in almost no configurations will they equal a half-wave dipole at comparable heights over real ground. Digest>Mr. Belrose has made a computer study of a number of small loop antennas at different frequencies and has tested several in an antenna laboratory. In this article he reports his results. He defines an "electrically small loop" as one with circumference between 0.04 and 0.1 wavelength. Such loops have very low radiation resistance and so, in order to obtain anything like a reasonable ratio of radiated power to power lost in the form of heat, one must reduce the resistive losses in the conductors, joints, and capacitor dielectrics to an absolute minimum. For computer-modelling, the tacit assumption is that all conductors are solid copper, all joints are welded rather than soldered, and capacitor dielectrics are air or vacuum. The author first analyzed a 3.4-meter (11 foot) diameter hexagonal loop mounted vertically over poor ground, with its center 2.5-meters high (about 8-feet). When operated at 3.75 MHz., the elevation plot of radiation shows that most energy is directed straight up! Even in that direction, the radiation is about 2.6 dB. weaker than that from an isotropic source, or nearly 5 dB. lower than that from a half-wave dipole at the same height. However, there is still appreciable radiation at usable angles. At an elevation angle of 30-degrees above the horizon, it is about 6-dB weaker than that of a dipole. At 15-degrees, it is minus 8-dB. At even lower angles, the intensity drops off rapidly: at 10-degrees to minus 10-dB, and at 5-degrees to minus 16-dB compared with the dipole. When the same antenna is raised to a height of 28-meters (about 92-feet), the radiation at 15-degrees elevation is only down about 3-dB from a horizontal dipole at the same height. Next, he modeled a 1-meter (40-inch) diameter loop on the 20-meter band mounted 15-meters (about 50-feet) high, both horizontally and vertically over poor ground. His plots show that the low-angle radiation that is so desirable on that band is much better from a horizontal antenna than a vertical one in this configuration. At 15-degrees elevation angle, the horizontal loop radiates about 3-dB. MORE than a horizontal dipole. With vertical polarization, however, the signal is down about 2-dB. below the dipole. When the same antenna is modeled over sea water instead of poor ground, the relationship reverses; with vertical polarization, the loop out-performs a dipole at all angles below 45-degrees, even down to near zero degrees. The signal from a horizontal loop, on the other hand, drops off quickly below 15-degrees elevation. Another graph shows the relationship between antenna gain and loop size over a wide range of frequencies. It shows that a 3.4-meter (11-foot) diameter loop can be used over a frequency range of about 1.5- to 8-MHz.; a 1.7-meter (about 5.5-foot) diameter from 2- to 14-MHz.; and an 0.8-meter (2-feet, 8-inch) loop from about 5 to 30 MHz. The radiated signal strength ranges from minus 14 dB. at the low end of the frequency range of each loop up to about minus 1 dB. at the upper ends, compared with dipoles. In all cases of small loops, minimizing resistive losses, coupled with the inherently low radiation resistance, causes the antenna to have a very high Q. The resulting bandwidths are quite narrow and the antenna must be retuned to resonance every time even a small change is made in the operating frequency. The author includes a graph plotting the 2:1 SWR bandwidth of each of the three antennas described. All three indicate a bandwidth of only 2- or 3-KHz. at the low ends of the frequency ranges listed above. At the high ends, they broaden to as much as 40-KHz. for the two larger ones and to 80-KHz. for the smallest one on the 10-meter band. To complete his study, Mr. Belrose tested two loops on the 80- and 40-meter bands. One was 3.4-meter (11-feet) in diameter, and the other 1.7-meter (5.5-feet). He compared them with an inverted-vee dipole. The loops were mounted at a height of 3.6-meters (about 12-feet), whereas the apex of the inverted-vee was at 15-meters (50-feet). His computer analysis predicted that the larger loop on 80-meters would perform down about 3-dB., and the smaller one on 40-meters about 1-dB, from the dipole. His tests made on the air bore out those results, within the accuracy with which he could evaluate them. _________ Title>TA5:Under the Hood II: Resistors Author>Bergeron, Bryan - NU1N Source>QST Nov 93, pp. 41-44 Abstract>A description of the types of resistors used in modern electronic construction. Digest>Resistors used in radio construction are practically all of three types: carbon composition, film, or wire-wound. The author describes each type in detail, how they are used, and what factors should be considered when using them. Carbon resistors are made of rod molded from particles of carbon mixed with other components to provide the desired resistivity. Wire contacts are attached to each end of the rod and the whole is molded inside a covering of plastic material. Film resistors are thin films of conductive metal deposited on insulating rods and trimmed to a final resistive value by a spiral groove cut in the film. Wire-wound resistors are made of resistance wire wrapped around an insulator. The author explains standard resistance values, the difference between fixed- and variable-resistors, power-dissipation capacity, tolerances, color-coding and -labeling, stability, noise, and frequency effects. _________ Title>TA6:An Accurate Dip Meter Using the MFJ-249 SWR Analyzer Author>Barton, David M. - AF6S Source>QST Nov 93, pp. 45-46 Abstract>Adding a simple coil, built into a PL-259 coax connector, to the MFJ-249 SWR Analyzer makes it an effective dip meter. Digest>Any ham who is interested in building r.f. equipment or experimenting with antennas needs a dip meter, an instrument that measures the resonant frequency of a circuit. It contains an oscillator that can be tuned over a wide range of frequencies and which has a coil that usually protrudes from the front of the instrument. When the coil is loosely coupled to a resonant circuit, and the oscillator is tuned to the resonant frequency, some of the energy from the oscillator is absorbed and there is a pronounced dip in current flow within the oscillator. The current is displayed by a milliammeter but, on conventional dip meters, the frequency is not measured. To determine the exact resonant frequency usually requires that the oscillator frequency be read on a digital counter not included with the meter. The MFJ-249 Analyzer is not, itself, a dip meter. It does contain an oscillator which is adjustable over a wide frequency range, and a digital counter that measures the oscillator frequency at all times to a high degree of accuracy. It also contains a meter calibrated in standing wave ratio (SWR); in normal use it is coupled to an antenna and reads the SWR on that antenna at the frequency at which the oscillator is set. Mr. Barton cleverly perceived that, with the addition of a small pick-up coil, a capacitor, and two resistors, the MFJ analyzer could be transformed into a very effective dip meter. In this article he explains its operation and shows how to assemble the very simple external circuit that effects the transformation. He explains its operation by observing: "Anything that removes energy from a badly-matched r.f. circuit improves the match, lowering the SWR." So he wound a small coil, loaded it with a parallel resistance, and attached it to the input of the MFJ-249. He used inductance and resistance values such that the SWR measures approximately 3:1 over most of the HF bands. When that inductor is loosely coupled to a resonant circuit, some of the oscillator energy is absorbed and the SWR indication dips in a manner exactly like that of a conventional dip meter. The circuit that the author uses is made of a 180-ohm resistor connected directly across the input of the analyzer. Connected in parallel with that resistor is a 15-ohm resistor in series with a 1000-pf. capacitor in series with a 0.7 microhenry pickup coil. That is the complete circuit! The stated value of the pickup coil is not at all critical; it is made from a piece of insulated hookup wire wrapped three times around one's finger, making a 3-turn coil, about 3/4-inch (18-mm.) diameter. The circuit is soldered into a PL-259 coax connector with the coil protruding from the body. The three-turn coil performs very well over almost the entire HF spectrum, but its sensitivity drops off a bit at the low end. To obtain higher sensitivity below 4 MHz., the author suggests adding one more turn to the coil. In a side-bar, the author addresses the problem of "how to dip a dipole". It is difficult to couple a pickup coil to a straight piece of wire, like a dipole. Most people make a small coil of one- or two-turns, attach it across the center insulator of the dipole, and couple the dip meter to it. This usually works, but the inductance of the inserted coil lowers the frequency of the antenna, causing an error in measurement. The way to overcome the detuning effect is to tune the auxiliary coil, independently of the antenna, to resonance at the same frequency. Prepare the small coil, connect it across a variable capacitor, and tune the resulting circuit to resonance at the desired frequency. Then, without changing the capacitor setting nor the shape of the coil, attach it across the center insulator with the coil and capacitor either in series, if it is at a low impedance point in the antenna, (as in the center of a dipole), or in parallel if at a high impedance point. Then couple the meter to the coil and dip the meter. ----------------------------------------------------------------------- PRODUCT REVIEW pp. 75-81 conductor: Mark J. Wilson, AA2Z QST Editor Title>PR1:MFJ-249 and MFJ-207 SWR Analyzers Author>Gruber, Mike - WA1SVF Source>QST Nov 93, pp. 75-77 Abstract>Description of the two MFJ SWR analyzers. They both measure SWR of antennas and are essentially identical except that the MFJ-249 contains a digital counter to display frequency, while the MFJ-207 does not. Digest>The MFJ-249 is the same unit described in the preceding article. The MFJ-207 is a less expensive model. The major difference between the two is that the '249 contains a digital frequency couter that displays frequency to a high degree of accuracy at all times; the '207 omits the counter. In addition, the '249 covers the frequency range from 1.8- to 170-MHz., whereas the '207 covers only 1.8- to 30-MHz. They both operate from self-contained batteries and are small enough to hold in one hand. The reviewer found that both units perform their functions well and make adjusting antennas very much easier. Using the meters, he erected two dipoles, one for 20-meters and the other for 6-meters. In pruning the 20-meter dipole, he measured each step with both meters, in turn, and also with a Bird Model 43 SWR Meter. He deliberately started with the wire too long, then pruned it a little at a time and made measurements with all three instruments. The resonant frequencies measured by the MFJ-249 can be considered the accurate ones; those determined by the MFJ-207 were sufficiently close for all practical amateur purposes, but it is much more difficult and cumbersome to measure frequency without the counter of the '249. The Bird meter does not measure frequency. For SWR measurements, all three instruments measured the same values, within 0.1, near resonance. Away from resonance, the SWR measurements differed a bit. To determine the significance of the differing SWR readings, Mr. Wilson took the two MFJ units into the laboratory and compared measurements against a high-precision Q-Meter. He set up a test circuit with a precisely known standing-wave ratio of five difference values: 50-ohms resistive (SWR 1:1), 25-ohms resistive (SWR 2:1), reactive 50 -j50 ohms (SWR 2.6:1), reactive 50 +j50 ohms (SWR 2.6:1). Then he measured each of these networks at 3.5-, 14-, 28-, 50-, and 144-MHz. and tabulated the results. Over the HF range, 3.5- to 28-MHz., the '249 never deviated by more than 0.1 from the true SWR measurement on purely resistive circuits. With the reactive loads, its readings were uniformly on the low side by as much as 0.3. The '207 read on the low side by as much as 0.3 with purely resistive loads and 0.5 for reactive loads. The '207 does not cover VHF bands but the '249 was tested on 50- and 144-MHz. It read the resistive loads on the high side by as much as 0.4, the capacitive load (50 -j50 ohms) low by as much as 0.9, and the inductive load (50 +j50 ohms) on the low side by up to 0.2. For ham purposes, these indicated errors are probably not significant. The analyzers can also be used to measure velocity factor and characteristic impedance of coax cables and also measure inductance and capacitance of components. The reviewer reports that they worked well in all those uses. His final summary is that he found the MFJ-249 to be his favorite, by far. The lack of an accurate frequency measurement with the MFJ-207 requires, in practice, that one dip the unit, then measure its oscillator frequency by means of a calibrated receiver tuning to zero beat. If the receiver is in the shack and the antenna some distance away, it becomes a nuisance to have to carry the meter into the shack each time the frequency must be determined. Also, the oscillators in both units drift with changes in temperature. If the shack is warm and the outside chilly, the frequency at which the '207 dips and that at which its oscillator is measured will not be the same. _________ Title>PR2:Tejas RF Technology Backpacker II Model TRFT-550 Single-Band CW Transceiver Author>Bauer, Jeff - WA1MBK Source>QST Nov 93, pp. 78-80 Abstract>Description of a very small, light-weight, low-power CW transceiver. Digest>The Backpacker II is a small, self-contained, CW transceiver. It is built for the 40-, 30-, 20-, 17-, or 15-meter bands. The one reviewed is the 40-meter model. Its frequency coverage is 7.0- to 7.2-MHz. Its maximum power output is 1.5-watts. In transmitting, the unit draws 228 ma. supply current, 53 ma. while receiving. The original Backpacker was designed by Roy Lewallen, W7EL, and was described in the August, 1980 QST. The receiver is a direct-conversion design in which the signal passes through the transmitter's low-pass filter "in reverse". In lieu of i.f. filtering, a low-pass audio filter is provided with three selectable bandwidths: 1088-, 304-, and 277-Hz. An RIT circuit allows plus or minus 1.5-KHz. shift. The front panel contains four knobs and a push-button: a.f. gain, filter selector switch, tuning, RIT, and the "SPOT" push-button that allows zero-beating. The reviewer found that the unit in its case is very solid. It holds its frequency while being subjected to shaking and hitting. The bandspread and stability are such that he found it possible to monitor AMTOR and PACTOR with ease. Full break-in keying is provided. _________ Title>PR3:SGC Inc. Model SG-230 "Smartuner" Automatic Antenna Tuner Author>Bauer, Jeff - WA1MBK Source>QST Nov 93, pp. 80-81 Abstract>An automatic antenna tuner, with very broad range, tunes by relay-switching capacitors and inductors according to settings in non-volatile memory, hence operates very rapidly. Digest>This unit is an automatic antenna tuner that can be used with any transmitter over a power range of 10- to 150-watts PEP. It can tune almost any antenna, hence its range is very much broader than the automatic antenna tuners supplied with most modern transceivers. In principle, its operation is very simple and straightforward. It is a classic pi-network, or series-ell network tuner. R.f. power from the transmitter is fed to the tuner; an internal directional coupler measures the reflected power and feeds the information to a self-contained microprocessor. The microprocessor, operating a program stored in "firmware", calculates the tuner configuration most appropriate and sets up the network by switching one of six input capacitors, one of eight inductors, and one of five output capacitors, by actuating relays. With no motors required to turn capacitors and/or variable inductors, tuning is very rapid. When it is complete, the settings are stored in a non-volatile memory which, over time, builds a table of values. As the table fills, the time required to retune drops to milliseconds! The reviewer's final summary states: "Although it is a bit pricey, the SGC-230 will match a variety of random-length radiators and is a good choice for mobile, marine, or "stealth" home antenna systems. ------------------------------------------------------------------------ HINTS AND KINKS pp. 82-83 conductor: David Newkirk, WJ1Z Sr. Asst Technical Editor _________ Title>HK1:Ten-Minute ID Timer Revisited Author>Conklin, John - WD0O Source>QST Nov 93, p. 82 Abstract>Update of design of a 10-minute timer made in 1991 to use currently-available components. Digest>In 1991, the writer designed an electronic 10-minute timer to "beep" in reminder of the 10-minute identification rule. It was published in HINTS AND KINKS in February, 1991. Unfortunately, the timer IC that the system used is no longer made. In this letter, he offers an updated version. A complete wiring diagram is shown, along with a list of all parts required. _________ Title>HK2:Curing Multi-Mode Communications Processor Distortion With the Kenwood TS-850S Author>Frost, Julian - KC6NSE Source>QST Nov 93, p. 82 Abstract>A simple adjustment to correct a problem with the TS-850S. Owners of the Kenwood TS-850S have reported that, when a multimode communications processor was connected to the accessory connector on the back of the '850, all digital mode and sideband transmissions from the transceiver became badly distorted. It was discovered that the problem can be fixed if the transceiver's "VR-18" trimmer is adjusted until the SSB distortion disappears. _________ Title>HK3:How to Connect an ICOM SM-8 Mike to the Yaesu FT-990 Author>Grandison, Earle - K6WS Source>QST Nov 93, pp. 82-83 Abstract>Adapting an ICOM microphone to use with the Yaesu transceiver. Digest>The writer wanted to use his ICOM mike with the Yaesu transceiver, but found that the microphone requires a +8.0-volt supply and the transceiver's mic-jack does not supply voltage. So he built a box containing an 8-volt regulator and filter to connect with the main power supply of 13.8 volts. He also indicates that a 9-volt battery could be substituted. A wiring diagram with plug and socket connections is included with the letter. _________ Title>HK4:Inductance of Small Coils Wound on Machine Screws Author>Zinder, Dave - W7PMD Source>QST Nov 93, p. 83 Abstract>A table of values of inductance achieved by winding wire around the threads of machine screws of various sizes. Digest>Mr. Zinder provides a very handy table of values which tabulates the inductance in micro-henries of small coils wound on the threads of machine screws as coil forms. The table includes coils of 1- through 6-turns wound on screw sizes from 6-32 to 7/16-14, as follows: Screw Size 1 2 3 4 5 6 6-32 0.016 0.024 0.032 0.044 0.058 0.062 10-24 0.017 0.028 0.043 0.057 0.072 0.088 1/4-20 0.021 0.035 0.055 0.077 0.095 0.121 5/16-18 0.022 0.044 0.067 0.096 0.123 0.158 3/8-16 0.026 0.052 0.083 0.118 0.152 0.201 7/16-14 0.030 0.061 0.098 0.143 0.199 0.240 The writer uses No. 20 bell wire for most of his coils, but for the 6-32 coils he uses No. 26 wire-wrap wire with the insulation stripped off. He finds the 10-24 and 1/4-20 coils to be most useful. He advises that the coil be wound on the screw and left on it while being soldered in place. Then the screw is simply unscrewed and backed out of the coil. He advises that the screw to be used as a form should be 3-inches long so that it can be supported while one is soldering the coil. Keep the coil near the screw's end so that unscrewing it does not require so many turns! _________ Title>HK5:Keep Your QST Binders in Shape Author>D'Antonio, Louis - WA2CBZ Source>QST Nov 93, p. 83 Abstract>How to stop QST binders from sagging out of shape. The writer advises that, to prevent the QST binders from sagging out of shape when full of magazines, a paperback book be inserted just inside the front and back covers of the binders. ------------------------------------------------------------------------ TECHNICAL CORRESPONDENCE conductor: Paul Pagel, N1FB Associate Technical Editor _________ Title>TC1:Yaesu FT-990 Computer-Control Interface Author>Lemmon, Paul S. - WD4BNO Source>QST Nov 93, p. 84 Abstract>Modifying a circuit described in QST Feb 93 for use with the Yaesu FT-990 transceiver. Digest>The writer comments about an article by W. Blackburn: "Everything You Always Wanted to Know About Hardware for Computer- Controlling Modern Radios" in QST, February, 1993. Mr. Blackburn's article recommended a circuit which used a pull-up resistor, whereas the Yaesu FT-990 requires a pull-down resistor, at a certain point in the system. His cure for Yaesu owners is to eliminate one resistor in the circuit. _________ Title>TC2:No Ions in the Cold, Cold Ground Author>Jones, Steven - KQ4WB Source>QST Nov 93, p. 84 Abstract>Describes the reason that frozen soil has very low conductivity. Digest>Mr. Jones responds to a letter from Roy Lewallen, W7EL, about the low ground conductivity that develops when the ground freezes to an appreciable depth. He advises that water content enhances soil conductivity because of ion migration, not because of metallic conductors in the soil. _________ Title>TC3:Small Antenna Efficiency Author>Lewallen, Roy - W7EL Source>QST Nov 93, p. 84 Abstract>Transmitting loop antennas described by Newkirk in QST Jul 93 are VERY inefficient. Digest>Mr. Lewallen comments about the article on small loop antennas, titled: "Honey, I Shrunk the Antenna!", by Rod Newkirk, W9BRD, printed in the July, 1993 issue of QST. The original article described multi- turn loops built with a tuning capacitor, or capacitors, in each loop. The author then went on to report surprisingly good on-the-air results using these antennas. In this letter, Mr. Lewallen points out how inefficient the loops that Mr. Newkirk described actually were. Using antenna analysis software, he calculated the loss due to the resistance in the copper wire only, not even considering the losses in capacitor dielectrics, leaky insulation, and other inefficiencies. His calculations indicated that the first antenna described by Mr. Newkirk, on 40-meters, had an efficiency of only 3.8 percent, meaning that 96.2 percent of the power was dissipated in the copper. When the antenna was tuned to 80-meters, the efficiency became 0.64 percent and copper loss was 99.36 percent of the input power. Finally, when a fourth turn was added and the new configuration tuned for the 160-meter band, the efficiency dropped to 0.07 percent, thus 99.93 percent of the power heated the copper wire! When the antenna was reduced to only 2-turns and tuned for the 20-meter band, the efficiency rose to 20 percent, and "only" 80 percent of the power was lost to heat. _________ Title>TC4:More on "Hands-Off Mobile Operation" Author>Wilson, George - W1OLP Source>QST Nov 93, p. 84 Abstract>Comments regarding the subject article by Hickox in QST Apr 90. Digest>Mr. Wilson responds to an article by Bill Hickox, K5BDZ, in the April, 1990 QST. His comments have to do with certain plug connections on several ICOM transceivers, and also the use of ferrite beads to cure r.f. feedback in certain other transceivers. ----------------------------------------------------------------------- FEEDBACK (FB) Title>FB1:"A Unified Approach to the Design of Crystal Ladder Filters" QST May, 1982 Author>Hayward, Wes - W7ZOI Source>QST Nov 93, p. 81 Abstract>In the referenced article: In Table 1, under the heading: "Normalized k and q Values for a Butterworth Response Without Predistortion", the value given for N=4, k23 is shown as 0.4512. That is in error; the correct value is 0.5412. ------------------------------------------------------------------------ THE NEW HAM COMPANION (NHC) THE NEW HAM COMPANION is a section in every QST, devoted to articles of primary interest to newcomers to ham radio. _________ Title>NHC1:Remedial Radio Author>Kleinschmidt, Kirk - NT0Z Source>QST Nov 93, p. 64 Abstract>Rules of etiquette for ham operation. Digest>Mr. Kleinschmidt discusses the various kinds of rude or inconsiderate behavior on the ham bands by a tiny minority of hams. Then he outlines a series of simple, self-imposed rules of etiquette which, if followed, will insure that the ham bands will continue to be pleasant places to "gather". _________ Title>NHC2:Trouble-Shooting Your Radio Equipment Author>Ricker, Harry - KC3MX Source>QST Nov 93, pp. 65-66 Abstract>"First Echelon Maintenance" for one's own ham gear. Digest>The author describes a number of steps that every ham should follow in case of a malfunction in their station equipment. Anyone can perform what the U.S. Army used to call "First Echelon Maintenance" which will solve the great majority of problems that arise. He states the "three ironies of trouble-shooting": "The first irony: Whenever you are absolutely certain that you have correctly guessed the cause of a failure, you will be wrong. "The second irony: Whenever you believe that an expensive, hard-to-find component is the cause of your failure, you will be wrong. "The third irony: The amount of effort required to replace a component is inversely proportional to the probability that it has failed." The entire gist of the article is that many people panic when something goes wrong and assume the worst. Many will pack up a piece of equipment and carry it, or ship it, to the repair station when, if they had taken the time to think through the problem and perform a few simple tests, they would have been able to correct it themselves. _________ Title>NHC3:The Doctor is IN Author>Various Source>QST Nov 93, p. 67 Abstract>Questions and answers for newcomers to ham radio. Digest>This is a regular monthly column in THE NEW HAM COMPANION, in the form of questions and answers often asked by newcomers. This month, the questions discussed dealt with keeping call signs when moving to a different call area; the difference between DRAMS and SIMMS in computer memory; seeing the Russian "Mir" space station with the naked eye; whether Coordinated Universal Time (UTC) changes for Daylight Saving time; the correct formula for a half-wave dipole at VHF; and grounding problems. _________ Title>NHC4:The ARRL Wants YOU! Author>Hurder, Luck - KY1T Source>QST Nov 93, pp. 68-69 Abstract>Description of the ARRL Field Organization Digest>Mr. Hurder explains what comprises the ARRL Field Organization and describes many of the activities it encompasses. He urges ham to make their stations official parts of the organization. _________ Title>NHC5:You Have a Date With Oscar 21 Author>Ford, Steve - WB8IMY Source>QST Nov 93, pp. 70-71 Abstract>How to use the Oscar 21 satellite for communication. Digest>Mr. Ford describes Oscar 21, which is physically a small electronics module "hitchhiking" aboard a Russian satellite. It is in polar orbit, so passes overhead twice each day, everywhere on earth. He describes its operations and explains how to listen to it and how to communicate with it. _________ Title>NHC6:I Wonder If... Author>Huston, Jack - W0JAW Source>QST Nov 93, pp. 72-74 Abstract>Construction of a controller to protect mobile gear from damage due to power surges caused by the starter motor. Digest>This is a construction article that describes how to build a controller that protects mobile equipment from damage caused by power surges that may occur when the car is being started. Included are a complete wiring diagram, parts list including suggestions as to where components can be bought, and instructions for construction. ------------------------------------------------------------------------ RADIO TIPS (RT) Radio Tips are short items that are scattered through THE NEW HAM COMPANION section and address subjects of interest to newcomers. _________ _________ Title>RT1:D.C. Power Supplies Author>Ford, Steve - WB8IMY Source>QST Nov 93, p. 74 Abstract> Digest>This is a description of the operation of a typical 12-volt d.c. power supply which draws power from the 120-volt, 60-Hz. mains and delivers 12-volts stable d.c. power. He describes how it works and what to look for when shopping to buy one. ------------------------------------------------------------------------ GENERAL INTEREST ARTICLES Title>GI1:Amateur Radio Aboard Space Shuttles Author>White, Rosalie - WA1STO Source>QST Nov 93, pp. 22-26 Abstract>History of ham operation on space shuttles. Digest>This year marks the tenth anniversary of the first radio amateur aboard a space shuttle. That occurred in November, 1983 when Owen Garriott, W5LFL, operated a 2-meter handheld transceiver with an antenna in the window of the ship's cabin. Ham activities were carried on on several subsequent flights until the CHALLENGER tragedy in January, 1986. When shuttle operations began again after the two-year hiatus, NASA cancelled all amateur activities. After strenuous efforts by ARRL personnel, NASA finally became convinced of the value of amateur radio in space and a shuttle amateur radio experiment (SAREX) was added to mission STS-35 on December 1, 1990. In April, 1991, the first all-ham space shuttle crew flew after pilot Ken Cameron, KB5AWP, convinced all the others to earn a license. _________ Title>GI2:Hello Again, to an Old Friend Author>Brady-Ciampa, Bart - N7NJL Source>QST Nov 93, p. 30 Abstract>Nostalgia. The author tells the story of a National NC-240-D receiver that he bought from another ham in 1958, when he was 16-years old. The old receiver was left in storage at his parents' home for many years while Mr. Brady-Ciampa continued his ham activities with modern solid-state gear. Recently, he reclaimed the old receiver and took it to his present home for reasons of nostalgia. When he again looked at the owner's manual, he noticed the name and call letters of the man from whom he had bought it 40-years earlier. He placed a call to the address shown in the call book and re-established contact with the original owner. Since then, they have exchanged many pleasant reminiscences. _________ Title>GI3:The Coming of the Law Author>Newkirk, David - WJ1Z Source>QST Nov 93, pp. 47-49 Abstract>Early history of laws regarding amateur radio. Digest>This is an historical article regarding the state of radio regulations during the years between 1902 and mid-1912. When the Radio Act of 1912 was passed, it contained a provision that many, perhaps including the drafters of the bill, thought would abolish amateur radio! That was, that amateurs were restricted to operation at shorter waves than 200-meters. Ironically, by specifically not abolishing amateur radio, the bill assured the survival of amateur radio. Shortly after its passage, the ARRL came into being and the rest of the story is reasonably well known to most amateurs. _________ Title>GI4:Solder to Talk Author>Nichols, Eric P. - KL7AC Source>QST Nov 93, p. 52 Abstract>Fiction: a parody on ham "old-timers". Digest>This is a parody on ham "old-timers" who mourn the passing of "the good old days" when radio was radio. The author tells of meeting a fictional ham who had a shack full of refrigerator-size tube-type radio gear. To transmit, he used a large soldering iron, plunged it into a can of flux, and soldered two heavy-gauge dangling wires together. When the hot iron caused blue smoke to rise from the flux, he breathed deeply and exclaimed: "Aaahhh, the smell of radio!" _________ Title>GI5:Hamming on the "Sunny Side of the Alps" Author>Sumner, David - K1ZZ Source>QST Nov 93, pp. 53-54 Abstract>Amateur radio in post-communist Slovenia. Digest>Mr. Sumner recently visited Ljubljana, the capital of Slovenia, where he met his counterparts at the Association of Radio Amateurs of Slovenia (ZRS). That is the English translation of the name in the Slovenian language and "ZRS" is its abbreviation. In this article, he reports what he found, how he was treated, and how he, his wife, and daughter enjoyed their visit. In short, ham radio is thriving in Slovenia. Actually, there are more hams per capita in Slovenia than there are in the USA! The Sumners were treated royally, and thoroughly enjoyed the trip. As for the their impression of the country, it is beautiful. In spite of the fact that terrible civil war is going on in Bosnia-Herzogovina, only about 100-miles away, and that all the other component parts of the old nation of Yuguslavia are armed to the teeth and living in a state of deprivation, Slovenia is peaceful, prosperous, and happy. Under the previous communist regime, only members of approved radio clubs could become licensed hams. The ZRS was part of the Yugoslavian National Radio Club which was closely controlled by the government. Now the controls are much looser and new laws are expected to go into effect soon. They will make a radio license an individual matter and membership in a club no more compulsory than that of the ARRL. _________ Title>GI6:The Australian Connection Author>Prudhomme, Alice - KG5ZZ Source>QST Nov 93, pp. 55-56 Abstract>Long-distance friendship via ham radio. Digest>This is a story of a friendship that developed between the author, a resident of Louisiana, and Clint Maile, VK2ACM, a native of Sydney, Australia. After having many chats on the air, Mr. Maile and a friend visited Louisiana and had many pleasant "eyeball QSOs". This is a report of the visit. _________ Title>GI7:Sweepstakes Shack on Wheels Author>indquist, Rick - KX4V/M Source>QST Nov 93, pp. 57-58 Abstract>Operating Sweepstakes from a parked automobile. Digest>The author decided to operate in the 1992 ARRL CW Sweepstakes from his automobile so that he could do it from a relatively rare section. He selected a spot in the parking lot of a motel in Ghent, West Virginia, at elevation 3000-feet plus. The operation was successful and he finished third in the West Virginia section with 64,500 points. He provides a series of recommendations for anyone who might want to do something similar: 1. Be sure the automobile exhaust system is in perfect condition and that exhaust fumes will not penetrate into the passenger compartment while the engine is running. 2. Make sure the battery is in top condition. 3. Plan for unusual weather, breakdowns, and "munchies". 4. Before leaving, test the rig on all the bands where operation is planned. 5. Take along an SWR meter and, perhaps, an antenna coupler. 6. Get a motel room with a decent restaurant nearby so as to get a good night's sleep during the contest. 7. Leave the six-packs at home. 8. Select a spot away from buildings and utility lines. 9. Run the rig at less than full power to maximize time between periods that the engine must be run to recharge the battery. 10. Provide adequate light. The author used a neon-tube trouble light that drew 8-watts. 11. Take along a portable receiver to monitor your own signal periodically. 12. Use headphones and keep the log on a laptop computer, don't try to log on paper. 13. Have your ham license and driver's license handy. Authorities will probably become curious to know what you are doing. _________ Title>GI8:Satellites and Field Day Author>Ford, Steve - WB8IMY Source>QST Nov 93, pp. 59-60 Abstract>Using satellites for Field Day communication. Digest>During the 1993 Field Day, Mr. Ford, ARRL Assistant Technical Editor, and Luck Hurder, KY1T, ARRL Deputy Field Service Manager, put the W1AW satellite station on the air. This is a report of their experiences and conditions that existed on the satellites during that event. Mr. Ford reports that Oscar 13 was not in a good position during the contest, so they concentrated their efforts on Oscars 20 and 21, and RS-10. When the activities actually began, they did make numbers of contacts on Oscar 13 and 21, but most of the activity was on Oscar 20 and RS-10. In the remainder of the article, Mr. Ford invited several other hams to relate their experiences in the same activity. _________ Title>GI9:How Does a Section Manager Spend Field Day? Author>Bowles, Chester S. - AA1EX Source>QST Nov 93, p. 61 Abstract>A Section Manager is very busy throughout Field Day. Digest>The writer logged the activities of New Hampshire Section Manager, Al Shuman, N1FIK, on Field Day, 1993 from 6:00 a.m. Saturday until Sunday evening. He drove 364 miles on Saturday and visited 7 clubs. On Sunday, he visited 5 clubs and drove 170 miles. The totals for the weekend were 12 visits, 534 miles, and 25 hours. ------------------------------------------------------------ 73, Van - W8UOF wvanho@infinet.com