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DIGEST OF ARTICLES -- QST January, 1994 Following are digests of articles printed in the Jaunary, 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:An Inexpensive SSTV System 69 TA2:The Nearly Perfect Amplifier 104 TA3:Computer-Controlled Electronic Test Equipment 172 TA4:Uncle Albert's Unique Keyer 231 TA5:III - Capacitors 268 PRODUCT REVIEW (PR) PR1:The Yaesu FRG-100 General Coverage Receiver 296 PR2:The MFJ-8100 Shortwave Regenerative Receiver Kit 336 PR3:Heil Pro-Set Headset 373 HINTS AND KINKS (HK) HK1:Ferrite Shield-Current Chokes Cure Stray RF on Vertical Antenna 413 Transmission Lines HK2:Another Simple Interface for Transceivers With RS-232-C Ports 439 HK3:Cutting Printed Circuit Boards 461 HK4:Adding Unsquelched Audio Output to the ICOM IC-228A Receiver 470 HK5:Minimizing TVI From the Yaesu FT-767GX Transceiver 494 HK6:Laundry Detergent Boxes Store QSTE 514 TECHNICAL CORRESPONDENCE (TC) TC1:Large Antenna Coils 530 TC@:More on Electrical Protection Devices 555 NEW HAM COMPANION (NHC) NHC1:Test Day 594 NHC2:The Doctor is IN 603 NHC3:A CHEAP Way to Hunt Transceivers 619 NHC4:Where's My Mail? 644 NHC5:Do You Need an Antenna Tuner? 676 RADIO TIPS (RT) RT1:Those Versatile Hand-Helds 714 RT2:Packet Snooping 727 RT3:Log It or Lose It 744 GENERAL INTEREST ARTICLES (GI) GI1:Antenna Radio Postage Stamps 760 GI2:Mother Nature's Radio 791 GI3:Before Spark 853 ------------------------------------------------------------------------ TECHNICAL ARTICLES (TA) Title>TA1:An Inexpensive SSTV System Author>Vester, Ben - K3BC Source>QST Jan 94, pp. 27-29 Abstract>An SSTV receive/transmit system entirely in software. It requires only a PC, simple interface, and conventional transceiver. Digest>In this article the author describes his development of a complete SSTV transmitting and receiving system done entirely in software! The only electronic apparatus required is an amateur transceiver, a personal computer, and a very simple interface using one integrated circuit (IC), plus a dozen passive components. He has made the software available free, and it can be downloaded from the ARRL Bulletin Board at (203) 666-0578. The name of the file is "vester.zip". The kernels of the program are written in assembler language for speed and efficiency, but additions and modifications can be made in Basic and "hooked" onto the kernel using "POKEs". The computer requirements are a DOS machine using an 80286, or later, microprocessor, although a '386 or better at 16- or 33-MHz. clock rate will give definitely better results. It should have a VGA-compatible color monitor and a "Super VGA" (SVGA) video adapter card. The transceiver can be any conventional SSB rig on HF, VHF, or UHF. If it is to be used with an AM or phasing-type SSB rig, or with FM transmitters, audio filtering will probably be required to assure sufficient spectral purity for good pictures. The article shows a number of photographs of the author's CRT screen. The color and resolution are very impressive, indeed. _________ Title>TA2:The Nearly Perfect Amplifier Author>Measures, Richard - AG6K Source>QST Jan 94, pp. 30-34 Abstract>Auxiliary and protective circuitry that can be added to any tube-type amplifier, greatly enhancing reliability and operating life. Digest>The title to this article might more properly be called "The Nearly Perfect Protective and Auxiliary Circuits for an Amplifier". The author makes a thorough and penetrating analysis of the auxiliary circuitry of a tube-type RF power amplifier, but does not discuss the RF aspects, at all! He does an excellent job of pointing out how relatively inexpensive additions and modifications can greatly improve the reliability and life, as well as the performance, of most modern commercially-built amplifiers. He considers each aspect of the power tube and power supply, in turn. First, he addresses the extreme sensitivity of a power tube's operating life expectancy to tiny changes in filament voltage and strongly recommends a voltage-regulated power supply. Second, he makes a convincing case that EVERY power tube should have a time-delay circuit to apply reduced voltage to the filament for a warm-up period before raising it to full rated voltage. Regarding the grid circuit, he observes that he has never seen an amplifier damaged by excessive HF grid current, but excessive grid current caused by VHF or UHF parasitics is a very common cause of tube destruction. Nevertheless, many commercial amplifiers are built with protective circuits to prevent excessive HF grid current but with totally inadequate parasitic suppression. He recommends a foolproof method of protecting the grid, which is insertion of a carbon-film resistor as a fuse. Another very common cause of severe damage to amplifiers is from accidental shorts of the high-voltage to ground. They can be caused by insects, fine threads sucked into the blower, or a myriad of other causes. At the instant of a short, the full charge in the power-supply filter capacitors is delivered and a peak current of hundreds of amperes passes through the plate current meter and, probably, causes an arc at the point where the short occurred. He cites one case in which the meter exploded!. At the instant of the capacitor discharge caused by a short, the negative high-voltage will surge to several kilovolts. The grid-current meter, normally connected from the negative high-voltage terminal to the chassis will thus also be subjected to a surge of hundreds of amps. Simultaneously, if the tube uses an indirectly-heated cathode, the negative high-voltage surge may cause an arc from the cathode to the filament, destroying the tube. All of this damage can be prevented by the liberal use of protective diodes that cost about 20-cents each! Next, the author looks at power supplies. The common use of parallel resistors and capacitors across each rectifier diode in a high-voltage rectifier is shown to be self-defeating. Instead, he recommends metal-oxide varistors. The voltage across filter capacitors should be equalized with resistors across each series capacitor, but care must be used to choose the proper resistor. He recommends 3-watt, 100,000-ohm metal-oxide-film resistors for 450-volt capacitors. The article concludes with several other recommendations regarding high-speed receive/transmit relays, VHF parasitic suppressors, and some other suggestions for specific cases. The author summarizes by pointing out that the total cost of everything that he recommends would likely not exceed $100, and might be considerably less. The end result would be a dramatic improvement in operation and safety of almost any amplifier on the market today. _________ Title>TA3:Computer-Controlled Electronic Test Equipment - Part 2 Author>Portugal, Ron Source>QST Jan 94, pp. 35-41 Abstract>Construction of a "mother board" to hold instruments to be built as described in future installments. Also construction details for building an L-C meter covering ranges of 1-microhenry to 5-henrys and 1-picofarad to 10,000-microfarads. Digest>In this installment, the author describes the construction of a "mother board" to hold all of the instruments to be built. Considering the total number of cables, leads, jumpers, and miscellaneous wires that would otherwise decorate the workbench, the use of a mother board that contains all the interconnecting wires on its etched surface can be seen to be a great advantage. The board is 12.5 x 7 inches (318 x 178 mm.) and contains 9 50-pin headers, each of which will accept a 5 x 6 inch (127 x 152 mm.) project board. In addition, there is a single 50-pin socket to expand the bus onto a second chassis, for future expansion. The power supply, construction of which was described in Part 1, is the first module to be installed on the mother board. The rest of this article is devoted to the construction of an L-C meter. It provides an unusually wide measurement range of both variables. It measures inductance over a range of 5-million-to-1 (5-henrys to 1-microhenry). The capacitance range is even greater, 10-million-to-1 (10,000- microfarads to 1-picofarad). Readout is on a 4-digit counter. Accuracy is determined by the precision of the components used but, since the measurements are developed in the computer, any errors can be removed by calibration using any arbitrary number of standard capacitors and inductors to establish points on the curve. Capacitance is measured by using the fact that if a capacitor is charged from a known voltage source through a known resistance, its charging rate is a measure of the capacitance. The meter measures the length of time the unknown capacitor requires to charge from one known voltage level to another. Inductors are measured by pairing them with known capacitors to form oscillator tank circuits. The frequencies of the resulting oscillations are measured and the inductance calculated from the resonance equation: L=1/C*(2*pi*f)^2. >From the preceding description, it can be seen that the raw measurements of both capacitances and inductances are time durations expressed as numbers of cycles counted in the signal from an oscillator. The oscillator used in capacitance measurement is a high-precision square-wave generator; in the inductance measurement, the oscillator is controlled by the L-C tank circuit. In both cases, the cycles are counted and the result entered into registers in the computer for conversion to engineering units. The author is offering partial kits of parts for both the mother board plus power supply, and the L-C meter modules. His price for the former, including shipping in the continental United States, is $100. For the L-C meter, $81. The only parts not included are a mounting frame for the mother board and a power switch with LED indicator for the power supply. _________ Title>TA4:Uncle Albert's Unique Keyer Author>Ulbing, Sam - N4UAU Source>QST Jan 94, pp. 42-44 Abstract>Construction of a keyer that displays ASCII characters as they are formed, and the code speed, on an LCD display. Digest>This article describes construction of a keyer combined with a code reader that displays the ASCII characters that are being sent on a ticker-tape-like LCD display. It also calculates the code speed and displays the words-per-minute on the same display. The keyer can be actuated be either an iambic key or an external bug. It also includes a 47-character memory and a random-character code-practice generator that displays what it sends. It can be actuated at speeds ranging from 8- to 40-wpm. The author's main goal in designing the code-reader and display was to improve the sender's "fist". The code reader does not lie. If the sender runs the letters together and, for example, makes "ti" into "d", the display shows it. If s/he forms an unintelligible character, the display shows an "&" (ampersand). Most CW operators would consider it a blessing if all other operators would use such a device! A complete wiring diagram and parts list is included. The unit uses a microcontroller type 87C51, the LCD display module, and a mere handful of other parts: 3 transistors, 4 diodes, an oscillator crystal, and about a dozen resistors and capacitors. The author offers a pre-drilled PC-board and a pre-programmed microcontroller with construction information and operating instructions for $38; a more complete parts kit including all electronic parts excepting only the enclosure and miscellaneous hardware for either $60 or $67, depending upon LCD size. He does not offer his software separately. _________ Title>TA5:III - Capacitors Author>Bergeron, Bryan - NU1N Source>QST Jan 94, pp. 45-48 Abstract>Elementary description of capacitors used in radio circuits. Digest>This is the third article in a series describing and illustrating electronic parts. Types of capacitors are described, illustrated in photographs, and the symbols used in circuit diagrams. The electrical characteristics of the various types are discussed in detail. The types of capacitors discussed at length are: electrolytics, film, air-variables, ceramics, mica, oil, and paper. Electrolytics are sub-classified as aluminum or tantalum; film as polypropylene, polyester, polycarbonate, polystyrene, polysulfone, or metalized film. Electrical characteristics described are capactitance, tolerance, rated voltage, equivalent series resistance, dissipation factor, dielectric loss-angle, frequency ratings, operating temperature limits, leakage current, temperature coefficient, power-handling capability, and expected operating life. The schemes used in labeling small capacitors is explained. ------------------------------------------------------------------------ PRODUCT REVIEWS (PR) Conductor: Mark Wilson - AA2Z QST Editor Title>PR1:The Yaesu FRG-100 General-Coverage Receiver Author>Newkirk, David - WJ1Z Source>QST Jan 94, pp. 73-75 Abstract>Review of Yaesu's FRG-100 receiver for the SWL market. Performance is good enough to rate as a respectable amateur station receiver. Digest>The Yaesu FRG-100 is a receiver designed for the Short Wave Listener market but performs well enough to do a respectable job as an amateur station receiver. In fact, it offers one performance feature that most current amateur transceivers do not provide. In CW operation, one can select the sideband being received. This, combined with RIT and variable pitch control allows one to use zero-beat as the ultimate audio notch filter. The circuit design is completely new; it is not just the receiver portion extracted from the design of one of the current Yaesu transceiver models. It comes with 52 programmable memories that store both frequency and mode, digital frequency counter with readout to the nearest 10 Hz., scanning of either the memory bank or the band, clock/timer, and switchable i.f. selectivity of 2.4-, 4-, and 6-KHz. as standard. Optional features available are: CW crystal filters - 250 and 500 Hz. width, FM reception, and a high-stability crystal synthesizer. It does not include a preamplifier, but its sensitivity on SSB and CW for 10 dB. signal-to-noise ratio is better than 0.25 microvolts. With a 500 Hz. CW filter, the noise floor was measured as better than -138 dBm. on both 80- and 20-meters. The dynamic range measured better than 113 db. on the same two bands. The third-order intercept was 1.5 dBm. on the 20-meter band. The receiver's first i.f. is at 47 MHz. and its image rejection is better than 60 dB. over the entire 1.8- to 30-MHz. HF range. The reviewer's final summary states: "...the compact FRG-100 packs a surprising performance wallop at a price that should make its competition worry." That price (list) is below $900, including one CW filter and the FM receiving unit. _________ Title>PR2:The MFJ-8100 Shortwave Regenerative Receiver Kit Author>Newkirk, David - WJ1Z Source>QST Jan 94, p. 76 Abstract>Review of a kit for building a regenerative receiver, using modern components. The completed unit gives surprisingly good performance in a very small, lightweight, attractive package. Digest>Many old-time hams have speculated about the result of someone using modern components and construction techniques to build a receiver, the design of which dates from pre-superheterodyne times. Now they can find out by building a kit available from MFJ. The result will be a receiver of surprisingly good performance built in a small, lightweight, and very attractive cabinet, powered by a single 9-volt battery. The circuit would be a classic "TRF" (Tuned Radio Frequency) except that the r.f. amplifier stage is broadbanded, not tuned. It uses three JFETs and an integrated-circuit audio amplifier. One of the JFETs is an untuned, grounded-gate r.f. amplifier and the other two are used as a Butler-oscillator regenerative detector. The detector's tuned circuit is switched over five bands from 3.5- to 22-MHz. The tuning capacitor has a built-in 6:1 reduction drive which, the reviewer found, "tunes the receiver well". The ARRL laboratory put the little receiver through performance tests similar to those given to the latest state-of-the-art superheterodyne receivers and found a quite-respectable sensitivity of -105 dBm. at 4- and 10-MHz. At 20-MHz., it was -90 dBm. Of course, with no tuned circuit ahead of the detector, the selectivity is not very good but nevertheless, its two-tone, third-order dynamic range measured 70 dB. with 100-KHz. tone spacing. This receiver would seem to be a fitting partner with a QRP rig to test the limits of communications using minimum equipment. In addition, it would be a nostalgia trip for many old timers! _________ Title>PR3:Heil Pro-Set Headset Author>Wilson, Mark J. - AA2Z Source>QST Jan 94, p. 77 Abstract>A headset with integral microphone designed for professionals. Digest>The Heil Pro-Set is a stereo headset/microphone combination assembly designed for professional use. The headband is thoroughly padded and adjustable with detents. The cushions on the ear pieces are replaceable and comfortable. The ear pieces are attached to the headband through a ball joint that allows considerable variation in angle in order to provide a comfortable fit for people with varying size and shape heads. The microphone is attached to the assembly by a swiveling boom that can also be adjusted in shape. It is easy to place the mike at its most comfortable location or to swivel it up and out of the way when it is not in use. The cabling from both ear pieces and the microphone pass through a common cable. At the plug end, the headphone plug is a conventional 1/4-inch (6-mm.) stereo phone plug. The microphone plug, however, is a 1/8-inch phone plug. In use, it is plugged into a mating socket on one end of a 12-inch (30-cm.) jumper, the other end of which terminates in a plug selected to fit the user's specific requirement. Transceivers differ in the microphone connector and Heil provides a selection of jumpers to fit. A purchaser of the headset is given a choice of jumpers included in the purchase price. Additional jumpers can be bought separately. The reviewer found that the headphones "sound great", they are comfortable to wear for extended periods, and the microphone produces audio that is "clean, crisp, and punchy". The list price, including one jumper, is $135; additional jumpers $13 each. ------------------------------------------------------------------------ HINTS AND KINKS (HK) Conductor: David Newkirk - WJ1Z Sr. Asst. Technical Editor _________ Title>HK1:Ferrite Shield-Current Chokes Cure Stray RF on Vertical- Antenna Transmission Lines Author>Palmer, Bruce R. - K0WM Source>QST Jan 94, p. 78 Abstract>Construction of an antenna feedline choke using ferrite cores strung on a piece of coax. Digest>The author had considerable difficulty resulting from r.f. feedback in his shack when using his Kenwood TS-940S and a kilowatt amplifier. He found that a ferrite-bead shield-current choke in the antenna feedline where it enters his shack solved the problem. He built the choke using 50 Type FB73-2401 ferrite beads, 15-inches (38-cm.) of RG-303 coax, and two coax connectors. He used PL-259 plugs with inserts designed for RG-58 cable, which is larger in diameter than the RG-303. To make a good fit, he put a 1-inch (2.5-cm.) length of heat-shrink tubing over the cable at the point where the connector was to be attached. To assemble the choke, he installed a connector on one end of the coax, threaded on the 50 beads, and put a length of heatshrink tubing over the entire string of beads to hold them in place. Then he finished the job by installing another PL-259 on the other end. _________ Title>HK2:Another Simple Interface for Transceivers with RS-232-C Ports Author>Shelhamer, Mark - WA3YNO Source>QST Jan 94, p. 78 Abstract>Interface converting RS-232-C voltage levels to TTL, and vice versa, using readily available components. Digest>In Hints and Kinks, QST Jan 92, WB4ETY described a simple level converter for connecting TTL-level serial ports to RS-232-C ports. The level conversion is often required because TTL-level voltages are 0 and +5, whereas RS-232-C levels are bipolar. However, some computer RS-232-C interfaces will work with TTL level signals, and no level conversion is needed for signals going from the transceiver to the computer. However, the RS-232-C levels from the computer back to the transceiver must be clipped, or voltage-limited, to avoid damage. For such cases, Mr. Shelhamer presents a circuit diagram using a single 74LS08 low-power Schottkey chip to make the interconnections. The circuit is not as simple as WB4ETY's, but it utilizes a chip that is much more readily available than the Maxim MAX232 that he used. _________ Title>HK3:Cutting Printed Circuit Boards Author>Gibson, Roger - K4KLK Source>QST Jan 94, p. 79 Abstract>An office-type paper cutter does an excellent job cutting PC board material, but the blade dulls rapidly and becomes useless for cutting paper. _________ Title>HK4:Adding Unsquelched Audio Output to the ICOM IC-228A Receiver Author>McLellan, Scott W. - ND3P Source>QST Jan 94, p. 79 Abstract>Adding a separate unsquelched audio output for packet so the operator can continue to listen to the squelched output. Digest>The author uses his ICOM 2-meter rig for both packet and voice. Because of the time delay in opening squelch, he operates the rig with its squelch wide open. To avoid annoying noise when no signal is present, he added an extra audio output line that is not squelched for use on packet so that he can leave the normal squelch setting in use but still have instant packet operation. To carry the unsquelched audio signal to the TNC, he disconnected the lead that previously used pin number 4 on the microphone jack. He obtained the unsquelched audio signal by tapping into the audio amplifier chain in the receiver portion at a point indicated in the schematic illustrated in the article. The signal that was previously carried on pin 4, which he disconnected, was "T.SQL BUSY", which was never used in his modes of operation. _________ Title>HK5:Minimizing TVI From the Yaesu FT-757GX Transceiver Author>Lee, Mitchell - KB6FPW Source>QST Jan 94, p. 79 Abstract>Stopping leakage of r.f. out through the power cord. Digest>Mr. Lee's transceiver generated TVI even when he was using a dummy antenna. He found that harmonics were leaking out of the rig through the 12-volt power cord. He lists 4 steps that may be used to stop the leakage: (1) Isolate the d.c. input line to the final amplifier. Current is carried by two Teflon-insulated wires from the power connector to the amplifier board. Slip as many ferrite and powdered-iron toroids and sleeves as possible over both. (2) While the wires are still disconnected, add by-pass capacitors at the Jones plug. (3) Check for TVI using the dummy antenna. If some is still occurring, go to step 4; otherwise the job is finished. (4) Shield the power cable using large diameter braid. Connect a banana plug to the braid at the transceiver end and plug it into the adjacent ground lug. _________ Title>HK6:Laundry-Detergent Boxes Store QST Author>Steinhorst, Ted - KA2BIG/7 Source>QST Jan 94, p. 79 Abstract>Boxes the right size to hold one year's QSTs. Digest>The author has discovered that a 9-pound, 13-ounce (4.45 kg.) size box of the detergent ALL will hold more than a year's worth of QSTs upright. To prepare the empty box for this use, he makes a diagonal cut across the front, whereupon it becomes a fine "poor man's" magazine holder. ------------------------------------------------------------------------ TECHNICAL CORRESPONDENCE (TC) Conductor: Paul Pagel - N1FB Associate Technical Editor Title>TC1:Large Antenna Coils Author>Johns, Bob - W3JIP Source>QST Jan 94, p. 80 Abstract>Describes a method of building large, heavy antenna coils. Digest>This letter describes, and illustrates with a drawing, a method of construction of very large and relatively heavy antenna coils. They are wound of copper tubing held in place by three spacers located around the periphery of the coil at 120-degree angular spacing. The spacers are made of PVC pipe split longitudinally. The two halves of the pipe are squeezed on either side of the coil turns and drawn down tightly with 3 or more sets of nuts and bolts. A notch is cut in each half of the pipe at the point where the coil turns are clamped, thereby firmly holding them in place. The drawing shows the assembled coil and the pieces of pipe that form the spreaders connected together using elbows, tees, and sections of pipe leading to a coupling that is screwed onto the end of the "metal element" of the antenna. The drawing is not dimensioned, but the use of so many pipe fittings in the mechanical support implies that the antenna, coil, and all, are very large, indeed. _________ Title>TC2:More on Electrical Protection Devices Author>Hart, Lee A. - N8DUA Source>QST Jan 94, pp. 80-81 Abstract>Additional means of protecting against reversed-polarity power supply. Digest>This letter adds suggestions for protection against reversed- polarity power supply, supplementing the ideas in Covington's article in QST Jul 93, pp. 40-41: "Reverse-Polarity Protection for Your Gear". The following suggestions are included in the letter: (1) Schottkey diodes have only half the voltage drop of silicon diodes, but their PIV ratings are limited to 20- to 40-volts. (2) Germanium diodes have even lower voltage drop and can have PIV as high as 200 volts. (3) For high currents, use a PNP germanium power transistor as a diode. Tie the base to the collector to act as the cathode and use the emitter as the anode. (4) Use a high-power bipolar transistor wired with the input voltage to the emitter, the output from the collector, and the base tied to ground through a resistor chosen to hold the base current to from 2 to 10 percent of the peak output current. If the input voltage will exceed plus/minus 6 volts, add a blocking diode in series with the base resistor. This circuit protects not only against reversed polarity, but also against a dead short on the output. (5) Use a bridge rectifier between input and output. This not only protects against damage due to reversed polarity, but also corrects it. (6) Use a relay: put a blocking diode in series with the relay coil so it will actuate only if the polarity is correct. ------------------------------------------------------------------------ NEW HAM COMPANION (NHC) The New Ham Companion is a regular monthly section in QST that concentrates on articles of primary interest to newcomers to ham radio. _________ Title>NHC1:Test Day Author>Bowles, Chester S. - AA1EX Source>QST Jan 94, pp. 62-63 Abstract>A description of what happens during a license exam session; describes the functions of the Volunteer Examiners; and lists what is required of the examinees. _________ Title>NHC2:The Doctor is IN Author>Various Source>QST Jan 94, p. 64 Abstract>Questions and answers, general. Digest>In this monthly column, questions discussed this month are: the correlation, if any, between S-meter readings and RST reports; a method that sometimes works to enhance the printing on aged glass vacuum tubes to identify the tube number; the meaning of solar flux, A-index and K-index; the meaning of QSZ; the slight delay that most transceivers exhibit between the actuation of the push-to-talk button and when the rig actually begins to transmit; and the "World-Wide Packet Pals Directory". _________ Title>NHC3:A CHEAP Way to Hunt Transmitters Author>Rickerd, Glen - KC6TNF Source>QST Jan 94, pp. 65-66 Abstract>Direction finding with an HT and a foil-wrapped mailing tube. Digest>This article outlines a very simple and surprisingly effective way that any hand-held VHF/UHF rig can be made into a radio direction finder. One needs only a mailing tube with sufficient diameter that the rig can be inserted into it. Wrap the tube with aluminum foil and secure it with tape. Hold it vertically and, while listening to a signal, lower the HT into the tube until the signal strength begins to drop. The HT should be suspended from a cord or carrying strap. Hold tube and all against your chest and tune in the signal being sought. Turn your body slowly around, noting the difference in signal strength. You will notice a deep null that will be quite sharp at some particular bearing. At that bearing, your back is directly facing the direction from which the signal is being received. That is all there is to it! This method works because your body is acting as an attenuator of signals being propagated directly from your rear. Putting the HT into the tube reduces the signal level to the point that the apparent sensitivity of the null is enhanced. _________ Title>NHC4:Where's My Mail? Author>Patterson, Dave - WB8ISZ Source>QST Jan 94, p. 67-69 Abstract>Using the Amateur Packet Radio Network. Digest>This article describes the Amateur Packet Radio Network, how it works, and how to use it. It is made up of dedicated hams who volunteer their efforts and their equipment to the task of transmitting messages for no compensation other than the satisfaction of getting the job done. With very few exceptions, every ham in the "lower 48" states is always within easy reach of a packet bulletin board system (PBBS) which s/he can use to tap into the network and send or receive messages to and from other hams. All the sender/receiver needs is a 2-meter FM transceiver (even an H-T), a terminal-node controller (TNC), and a computer. To send a message to another ham, it is only necessary to know the radio address of the PBBS where the intended recipient picks up his/her mail. The sender composes a message in the manner described in the article and sends it by packet to the local PBBS. The computer at the local PBBS scans the address, and "decides" from information stored in its memory, to which PBBS it should be sent to advance it toward its ultimate destination. This happens again and again until the message arrives at the destination PBBS, marked for the recipient to claim. The author urges all hams to participate in this pleasurable aspect of amateur operating. For further information, he recommends obtaining a copy of YOUR PACKET COMPANION, by Steve Ford, WB8IMY, published by the ARRL. _________ Title>NHC5:Do You Need an Antenna Tuner? Author>Ford, Steve - WB8IMY Source>QST Jan 94, pp. 70-72 Abstract>Description of antenna tuners and their uses. Digest>This is a brief explanation of what an antenna tuner is, what it does and, equally importantly, what it does not do. One should use an antenna tuner if: (1) You want to use open-wire feedline to the antenna. (2) If you want to operate the antenna on bands other than the one for which it was cut. (3) The antenna has a narrow SWR bandwidth. One should not bother with an antenna tuner if: (1) The indicated SWR without a tuner is 1.5:1 or less. Making the SWR seen by the transmitter less than 1.5:1 will yield no additional benefits; it is good enough the way it is! (2) At VHF/UHF. Use of an antenna tuner will reduce the SWR "seen" by the transmitter but will not affect the SWR on the feedline. High SWR on a feedline at VHF/UHF causes very high loss of power. The problem must be corrected at its source: the antenna. (3) If you are suffering to TVI. Contrary to common opinion, use of an antenna tuner will probably have little effect on interference problems. Various features to look for in antenna tuners are explained, such as roller- or tapped-inductors, built-in SWR meters, a built-in balun, and others. Also the author makes recommendations regarding power ratings and whether to buy or build a tuner. ------------------------------------------------------------------------ RADIO TIPS (RT) These are short items, scattered among the articles in the NEW HAM COMPANION section. _________ Title>RT1:Those Versatile Hand-Helds Author>Kleinschmidt, Kirk - NT0Z Source>QST Jan 94, p. 66 Abstract>General description of hand-held VHF/UHF transceivers (HTs). Digest>The author makes a persuasive case for the fun of using a hand-held VHF/UHF FM transceiver. He describes using it to access a repeater, using it from an automobile, or while walking around a flea market to keep in touch with friends. He also suggests using it from the shack with an outdoor antenna, and with a TNC, in the packet mode. _________ Title>RT2:Packet Snooping Author>Ford, Steve - WB8IMY Source>QST Jan 94, p. 69 Abstract>Monitoring packet traffic to learn about local activity. Digest>Newcomers to packet radio can find out what is going on in their area by using the command: MCOM ON, which causes the system to display every packet it hears on a particular frequency. Some TNCs use a variation of MONITOR, rather than MCOM, to do the same thing. >From watching this activity, one can learn the call signs of local PBBSs, personal mailboxes, nodes, and digipeaters. Then s/he can try connecting to some of these stations and will soon learn which are within reach and which are out of range. _________ Title>RT3:Log It or Lose It Author>Kleinschmidt, Kirk - NT0Z Source>QST Jan 94, p. 72 Abstract>Using a station log book. Digest>All hams are encouraged to use a log, even though it is no longer required by FCC regulations. A record of QSOs is necessary for awards and contests; it is also a good place to record changes of equipment, maintenance procedures performed, or modifications made. Also for memory's sake, it is a lot of fun to review old logbooks and recall pleasant QSOs. ------------------------------------------------------------------------ GENERAL INTEREST ARTICLES (GI) _________ Title>GI1:Amateur Radio Postage Stamps Author>Welsh, Bill - W6DDB Source>QST Jan 94, pp. 22-26 Abstract>Summary of postage stamps that have been issued honoring ham radio. Digest>Many countries in the world, including the USA, have issued stamps that honor ham radio, or for other reasons are of special interest to hams. This article explains how stamps can be obtained, how they should be handled, stored, and/or exhibited as a collection, and the fact that some collectors prefer to collect blocks of stamps or "covers" bearing the stamps, rather than just the stamps, themselves. "Covers" are cards or envelopes to which the stamps are affixed and which, perhaps, have been sent throught the mail. As a 2-page "side-bar" with the article, is a list of the stamps that have been issued by many countries specifically honoring ham radio. The author has assembled a larger list of stamps that are of special interest to hams, although they do not specifically honor ham radio, per se. That list may be obtained for an SASE sent to Technical Department Secretary, ARRL, 225 Main St., Newington, CT 06111; ask for the "Stamp List". The article also includes a list of "Sources of Help", including the addresses of certain stamp dealers who specialize in amateur radio stamps. _________ Title>GI2:Mother Nature's Radio Author>Schneider, David - AD4CC Source>QST Jan 94, pp. 49-51 Abstract>VLF signals from natural causes. Digest>Phenomena that occur in earth's atmosphere and in adjacent outer space cause a variety of radio signals at very low frequencies. In fact, most of them are at frequencies normally considered audio, i.e. under 20 KHz. But they are electromagnetic, not acoustic, so can only be detected by a radio receiver. Modern hams may be surprised to learn that radio waves at audible frequencies can propagate for long distances. But the pioneers of early radio were very aware of it. Much traffic was handled at frequencies below 20 KHz in the 1920's and '30's. Natural radio noise, or QRN, is caused primarily by lightning and by emanations from the sun. Thunderstorm static is well known to everyone, and is a very broad-band effect, but most of the radio energy is concentrated at frequencies below 5 KHz. for a very good reason. The wavelength of a 5 KHz. radio signal is about 60 km. (36 miles). This is the same order of magnitude as the height of the D-layer that defines the ionosphere, so the space between it and the ground acts as something like a waveguide. Using it, "ground wave" signals easily propagate around the world. Compiler's Note: During World War 2, the USAAF Weather Service maintained a long-range storm tracking net (called "Sferics") that accurately plotted the positions of thunderstorms across thousands of miles of both the Atlantic and Pacific Oceans. The nets used simple radio direction finders operating at 10-KHz., with several stations based on islands hundreds of miles apart, to get precise triangulation on the positions of lightning strikes. The same lightning-induced signals also propagate through distances even more vast using the earth's magnetosphere. In this way, very low frequency radio waves leave the earth and travel through a great loop of more than 100,000 miles (170,000 kms.) in a beam that is approximately aimed at a spot in the opposite hemisphere at about the same longitude and the opposite latitude (the "conjugate point") from where it originated. During transit the magnetosphere, the lower frequency components of the static are delayed relative to the high frequencies. Consequently, when one listens to the raw signal, that is the acoustic signal that accurately reflects the frequencies of the radio signal, one first hears the high frequency; over a second or two, it rapidly drops to a low frequency. This is called a "Whistler". There is so little attenuation of the signal during its passage through the magnetospere that the same signal can bounce back and forth several times between the point of origin and the conjugate point. The more bounces that the signal takes, the greater is the time delay between the high- and low-frequency components. Accurate recordings of Whistlers give valuable information regarding the ionosphere and the magnetosphere. Amateurs can help by recording Whistlers, in cooperation with studies now being conducted by NASA and by Northern Kentucky University with a NASA grant. The author requests that interested hams contact him at: Northern Kentucky University, Department of Physics and Geology, Highland Heights, Kentucky 41076. _________ Title>GI3:Before Spark Author>McElroy, Gil - VE1PKD Source>QST Jan 94, pp. 57-59 Abstract>Wireless communications before radio. Digest>Most people believe that Marconi "invented" radio. To some extent, he deserves that credit because he made a practical communications system out of what was, before his work, an obscure laboratory phenomenon. But other experimenters had succeeded in transmitting intelligible electrical signals over appreciable distances decades earlier than Marconi's work. This article describes some of them. Samuel F. B. Morse, after he perfected the telegraph, experimented with wireless telegraph using water to carry the electric current. In 1842, he succeeded in transmitting a telegraph signal across a river, a distance of nearly a mile. The first person who succeeded in transmitting through air was apparently Dr. Mahlon Loomis, a dentist. At the close of the Civil War in 1865, he flew two kites, carrying wires, from mountain tops 14-miles (23-kms.) apart. The wire from one kite was attached to ground through a telegraph key; the other kite-wire was grounded through a galvanometer that could measure very small currents. When he operated the key, detectable changes of current occurred in the other kite wire. He was granted a patent on his system in 1872, but no known attempt was made to make use of the phenomenon commercially. Interestingly, the experiment was duplicated 44 years later in London where, during a hailstorm, experimenters successfully communicated over a distance of 3-miles (5-km.) In a parallel development, the idea of communicating by electrical induction occurred to numbers of people. In 1845, John Wilkins of Britain, proposed communicating across the English Channel by electro-magnetic induction. Not until 1891 was a successful demonstration of such communication made. That was done by an American, John Trowbridge. Using enormous wire coils mounted on a ship, he demonstrated that he could induce signals in a similar coil on the shore over a short distance, but even he admitted that he saw no practical value in the system. A few years later, several individuals conducted experiments to create "wireless telphony". The most successful one was Nathan B. Stubblefield, who demonstrated two telephones communicating by an inductive link in Murray, Kentucky in 1902. His coils were not tuned, but he stated his intention to develop a method by which several, separate communications could be conducted using the same coils at the same time, implicitly anticipating some aspects of radio. His experiments convinced the Legislature of the State of Kentucky which, in 1944, resolved that Nathan B. Stubblefield was "the true inventor of radio". ------------------------------------------------------------------------ wvanho@infinet.com