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HAM DIGEST -- QST, February, 1993 Following are digests of articles printed in the February, 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 TA1:A High-Dynamic-Range MF/HF Receiver Front End (74) TA2:YOU Can Operate HF Mobile (109) TA3:A New Standard for Amateur Radio Analog Facsimile (141) TA4:Everything You Always Wanted to Know About Hardware for (193) Computer-Controlling Modern Radios PRODUCT REVIEWS PR1:ICOM IC-728 and IC-729 Transceivers (250) PR2:ICOM AT-160 Automatic Antenna Tuner (309) PR3:A & A Engineering ViewPort VGA Slow-Scan TV System (333) TECHNICAL CORRESPONDENCE TC1:At the Races (412) TC2:Adapting the NU1N Voice-Control Program to the Yaesu FT-747GX (430) TC3:L-C Constants (445) HINTS AND KINKS HK1:Operate QRP With an Easy-To-Build Attenuator (470) HK2:Improved "Psycho-Regulation" and Arc Protection for High- Voltage Power Supplies (506) HK3:Two-Meter Coaxial Antenna (553) LAB NOTES LN1:What Rig Should I Buy? (589) FEEDBACK FB1:Dipoles Above Real Earth (610) FB2:An Inexpensive, Expanded-Range Analog Voltmeter (630) NEW HAM HORIZONS NHH1:W1AW at the Flick of a Switch (649) NHH2:Two-Meter FM Mountaintopping...Sort Of! (663) NHH3:Beyond FM (677) NHH4:The Doctor is IN (690) NHH5:Falling in Love With Ham Radio for Less Than $200 (705) GENERAL INTEREST ARTICLES GI1:Hurricane Iniki Rallies Amateurs (724) GI2:Classic Rigs and Amplitude Modulation: Friendly, Nostalgic (741) Ham Radio Partners GI3:Ham Radio at Soviet Space (765) GI4:Endurance - Is Geography the Only DX Dimension? (797) ------------------------------------------------------------------------ TECHNICAL ARTICLES (TA) Title> TA1:A High-Dynamic-Range MF/HF Receiver Front End Author> Makhinson, Jacob - N6NWP Source> QST Feb 1993, pp. 23-28 Abstract> Construction article. Receiver front end. 2-tone dynamic range: 111 dB. Intercept: +33 dBm. Better than Yaesu FT-1000. Single conversion, 9-MHz. i.f. Mixer: quad DMOS FET. Digest: This is a design and construction article describing a state-of- the-art receiver front end with a 2-tone dynamic range of 111 dB. and an intercept point of +33 dBm. These measurements were made with the pre- amplifier in operation and with an i.f. bandwidth of 2.4 MHz. The indicated performance figures are substantially better than those shown by the Yaesu FT-1000, one of the most advanced commercial receivers on the market. Thus the system combines high sensitivity with very strong signal-handling capability, the most challenging criteria in receiver design. Yet, it can be built and adjusted using the test equipment available to most amateurs who are oriented toward construction. The system features single-conversion with a 9 MHz. i.f. Much of the high performance and low intermodulation distortion are determined by the choice of a DMOS FET quad mixer. The author describes the criteria he used in selecting it, as well as the pre-amplifier and post-mixer amplifier, both of which use push-pull circuits with two transistors each. The three major components: pre-amplifier, mixer, and post-mixer amplifier, are built as separate modules, each in its own aluminum box. The input and output impedance of each is 50 ohms; the resulting flexibility encourages future experimentation. When conventional i.f. and audio circuitry is added, home builders can achieve truly state-of- the-art performance in a receiver. _________ Title> TA2:YOU Can Operate HF Mobile Author> Burch, Roger - WF4N Source> QST Feb 1993, pp. 29-30 Abstract> Overcoming two problems installing HF transceiver and antenna on a modern automobile: bumper mounting and driver-compartment space. Digest> In this article, the author describes how he overcame two problems that face hams when they try to install an HF transceiver and antenna in and on a modern automobile. First, the so-called bumper is apt to be rubber covered or shaped in such a way that it is difficult, if not impossible, to attach an antenna to it. Mr. Burch designed and fabricated an aluminum bracket that reaches under the bumper and fastens to the frame of the automobile. On it he mounted his Hustler antenna. Then he made a small bracket which allows him to mount as many as four separate resonators on the antenna, thus providing multi-band operations. The other problem that he had to overcome was the very restricted space for the mounting the transceiver in the front of the passenger compartment. He overcame this by designing and building a wooden platform that straddles the center hump ahead of the front seat. Finally, he fabricated another small wooden platform on which he mounts a keyer so that he can operate CW mobile. The author noted that the bracket holding the transceiver should be securely fastened to the floor of the automobile, but apparently lets the keyer platform simply rest on the seat. The editor has appended a note recommending that a more secure mounting system be employed if one plans to operate CW regularly. _________ Title> TA3:A New Standard for Amateur Radio Analog Facsimile Author> Taggart, Ralph E. - WB8DQT Source> QST Feb 1993, pp. 31-36 Abstract> A proposed new standard for transmitting analog facsimile images. Suggests 480 lines with 16 colors, or 16 shades of gray in black/white. Complete picture transmission time: 2-min 18.3 sec. Digest> This article proposes a new standard to be adopted by the world ham community for transmitting analog facsimile images. It begins by relating the history of facsimile transmission that evolved early in this century. That was when it first became possible for high- resolution photographs to be transmitted around the world for newspaper publication. Transmitting high-resolution photographs over noisy channels, then as now, requires long transmission times. Typically, five to twenty minutes is required for a newspaper-quality photo to be transmitted over a long-distance telephone circuit or HF radio circuit. The first significant amateur activity with facsimile developed when a few hams used surplus Western Union equipment to receive weather satellite photographs. Aside from that activity, the only ham activity the transmission of images has been slow-scan television (SSTV), which the author equates with facsimile. He then relates the history of the development of SSTV from its beginnings with coarse images consisting 120 lines vertical resolution, black and white, and evolving to the current standard of 240 lines of full color. But such images are still relatively coarse compared to photographs, and the author decries the fact that there has been almost no ham activity in high-resolution facsimile. He discusses the pros and cons of increasing the number of lines, increasing the number of pixels per line, and increasing the rate of data transmission. On the High Frequency bands, the rate of data transfer is severely limited by the 3.0 KHz. bandwidth restriction, so increased resolution can only be taken so far until the transmission time becomes impractically long. After weighing all the variables, Mr. Taggart settled on a specification of 480 lines with 16 colors, or alternatively, 16 shades of gray in black and white. Using that standard, the transmission time for a complete picture is 2 minutes, 18.3 seconds. The article contains black and white photographs taken from a CRT screen of a test unit utilizing the proposed standard and the detail in the photographs is impressive, indeed. The remainder of the article discusses in detail the hardware and software requirements and urges the amateur community to adopt the plan as the logical next step in facsimile development. _________ Title> TA4:Everything You Always Wanted to Know About Hardware for Computer-Controlling Modern Radios Author> Blackburn, Wallace R. - AA8DX Source> QST Feb 1993, pp. 37-39 Abstract> Explains RS-232-C serial port as used in popular HF transceivers. Describes TTL standards and how they differ from RS-232-C. Gives specifications and source for interface needed between equipment following the two standards. Digest> Most modern HF transceivers have provisions for control by external computers. Each unit is equipped with a serial communications port identified as RS-232-C, referring to an industry standard. When a manufacturer builds equipment with a port that conforms to that standard, the customers are assured that it will be able to communicate through that port with any other piece of equipment similarly equipped. The label: RS-232-C is simply the document number of an engineering standard that was recommended and published by the Institute of Electrical and Electronic Engineers (IEEE). It defines the number of conductors, the functions of each conductor, the voltage levels and pulse characteristics that flow across them, and many other parameters. The RS-232-C standard is designed to send binary data across relatively long lines, 50 feet long, or more. The author discusses, in detail, the functions required in controlling the equipment made by each of the four major manufacturers of ham gear. Although the transceivers are equipped with RS-232-C ports, and use the standard voltages for information transfer, the voltage levels required for control are different. They are defined by the TTL standard (transistor-to-transistor logic). Thus, even though the computer and transceiver both have RS-232-C ports, and they can communicate data, the control signals have to be changed to different values. Hence, an interface is necessary. This article describes the design and construction of a relatively simple, but complete, interface which allows one to implement computer control of any of the modern transceivers built by Ten-Tec, Kenwood, ICOM, or Yaesu. Wiring diagrams and parts specifications are included. In a side-bar with the article he also gives a complete description of both the TTL standard and also the RS-232-C. The side-bar alone is an excellent reference resource, useful to anyone interested in computer control and interfacing. Printed circuit boards and complete parts kits with assembly instructions are available from CW Enthusiasts, 1346 Erickson Ave., Columbus, OH 43227. PC board templates are available from the ARRL Technical Department Secretary for a business-size SASE. ------------------------------------------------------------------------ PRODUCT REVIEW (PR) Conducted by: James W. Healy, NJ2L Sr. Asst. Technical Editor _________ Title: PR1:ICOM IC-728 and IC-729 Transceivers Authors> Wolfgang, Larry - WR1B and Healy, Rus - NJ2L Source> QST Feb 1993. pp. 67-71 Abstract> Specifications and performance review of ICOM's two "entry- level" HF transceivers. Digest: The two transceivers reviewed are ICOM's "entry-level" HF rigs. They are identical except that the IC-728 covers frequencies from 30 KHz. to 30 MHz. whereas the IC-729 extends reception to include the band from 46.2 to 61.1 MHz., and transmitting coverage of 50-54 MHz. Although these are entry-level radios, they have most of the features common to more sophisticated (and expensive) models. Each includes two VFO's, 26 memories, optional 500- or 250-Hz. CW filter, noise blanker, r.f. pre-amplifier, pass-band tuning, fast or slow AGC, and speech processor. Transmitter output is adjustable from 10 to 100 watts on all bands, except for 10 watts on the IC-729 6-meter band. They provide RIT control, but not XIT. However, if the user tunes a station with the RIT control, the transmitter can be moved onto the same frequency by manipulating the "Function" button, a front-panel control. Zeroing the RIT requires manually centering the knob. Although these rigs do not support FSK operation, the digital modes are available using AFSK if one feeds audio tones into the mike input. Automatic antenna tuners are available for use with these rigs. I-Com has several models available; the one specially fitted to operate with the IC-728 and IC-729 is reviewed below. Other optional accessories are several speakers and three types of microphones. Tests made in the ARRL laboratory show that the performance specifications claimed by the manufacturer are practically all verified. The reviewers report that the rigs perform well in operation. In CW the offset is fixed at 800 Hz. which will be considered a drawback by many operators. Although no full breakin mode is provided, the shortest selectable semi-break-in delay unkeys the transmitter between dots at 20 words per minute. Most operators would find that sufficiently close to full break-in for normal conditions. A more serious drawback is the fact that the delay time setting is made by a screwdriver adjustment of a recessed rear-panel control. This will be seriously inconvenient for any CW operator except one whose operation is always at about the same code speed. In single sideband operation, the rigs produce high-quality audio. The reviewers find the lack of an ALC or Compression Level meter indicator disconcerting . The instruction manual suggests setting both knobs between "10 and 12 o'clock", but there is no good way to verify that the mike gain and speech-processor level controls are set to optimum values. Their summary judgement is that the two rigs are "solid entry-level performers". They feel that the IC-728 is "a solid light-weight radio that lends itself well to mobile and portable operation....In ease of use it is a hands-down winner." _________ Title> PR2:ICOM AT-160 Automatic Antenna Tuner Authors> Wolfgang, Larry - WR1B and Healy, Rus - NJ2L Source> QST Feb 1993, p. 71 Abstract> Specifications and performance review of antenna tuner designed to work with IC-728 or IC-729 transceivers. Digest> The same reviewers who reported on the ICOM transceivers above also reviewed the automatic antenna tuner which matches them. It uses relay-selected inductor taps and motor-driven capacitors to match antennas on the 160- through 10-meter bands. It will handle loads with SWR of up to 3:1. The IC-728 or -729 provides control signals that make the tuning automatic. A bracket is provided to mount the tuner on either side of the radio. The AT-160 can be connected to a single antenna or it can also be used with the I-Com EX-627 automatic antenna selector which will automatically select among up to 6 antennas depending upon the operating frequency. Although the tuner is designed to match the antennas with SWR of 3:1 or less, the reviewers found that, in operation, it successfully matched antennas with indicatad SWR as high as 10:1. _________ Title> PR3:A & A Engineering ViewPort VGA Slow-Scan TV System Author> Taggart, Ralph - WB8DQT Source> QST Feb 1993, pp. 72-74 Abstract> A review of hardware and software interface to link an IBM- compatible computer with a transceiver to form an integrated SSTV system. Digest>This system is an interface comprised of hardware and software to link between an IBM PC, or compatible, computer and a transceiver to make an integrated SSTV system. Unlike most interfaces, this one uses the computer's parallel port, rather than an RS-232 serial port. This has the advantage that almost every computer is supplied with a parallel port, normally used to drive a printer, but to obtain a serial port usually requires the purchase of an extra plug-in board. Ironically, the reviewer found that he could not make the system work with his genuine IBM PC. He learned that the problem results from the fact that most IBM clones use a slightly different parallel-port assignment than do true IBM PC's. The manufacturer of the interface designed it to fit the clones, with the result that anyone using a true IBM computer must buy a separate plug-in board containing a parallel port. The reviewer suggests that this problem can probably be easily fixed in software, and A & A Engineering will probably implement the change. The software requires that it be loaded directly into the DOS operating system, not through the Windows shell. The program presents three top-level menus: Receive, Transmit, and Additional Functions. The Receive menu lists ten different Black/White or Color modes, but the Transmit modes are limited to six. The four "Scottie" and "Martin" modes are not implemented for transmitting because the hardware does not provide sufficient accuracy in the time base for proper synchronization. These more demanding modes can be received only because line-sync is provided by the transmission format. The reviewer found when operating the system in receiving, it handles Black/White modes flawlessly. However, when one wants to save the images on a disk, they can be recorded only in a color format, thus the images acquire a color alias when they are reloaded. When receiving color formats, the interface does an excellent job, but for best results the computer must be equipped with a 32,768 color VGA board. If the VGA is limited to 256 colors, the display is less satisfactory. One annoyance is that when one switches into Receive mode, if the system does not receive a sync pulse, it "hangs up". The operator can usually restore operation by tuning off frequency a bit to get a 1200 Hz. beat note. Otherwise, the system must be re-booted. In transmitting mode, image quality is excellent. Images retain the full 32,768 color spectrum. The reviewer notes that the major problem that users must watch out for is external r.f. noise that becomes very obvious on images received from relatively weak signals. Some of the worst noise-makers are computers. He found that the IBM-made computers are relatively noise-free since they are in well-shielded cases with ample noise- suppression components installed internally. The clones that he used, however, were very noisy. He suggests that any noise problem can be overcome with sufficient attention to shielding, filtering, and by-passing, but it helps greatly to have a quiet computer to begin with. Purchasers would be well advised to take a short-wave radio with them to the computer store to evaluate computers they might want to buy. His summary opinion is that the interface was properly adjusted when it was received and functioned perfectly throughout the evaluation. As for the software, he suggested three upgrades: (1) Support for true-IBM parallel ports; (2) a hot-key "Exit" function for times when a sync pulse is missed in Receive mode; (3) a dedicated format for saving monochrome images to disk. ------------------------------------------------------------------------ TECHNICAL CORRESPONDENCE (TC) Conducted by: Paul Pagel, N1FB Associate Technical Editor _________ Title> TC1:At the Races Author> Vogt, John V. III - KM4OB Source> QST Feb 1993, p. 77 Abstract> Describes a theoretical problem that may arise in W9GR DSP unit described in QST Sept 1992. Digest> Mr. Vogt writes about a theoretical timing problem in the W9GR Digital Signal Processor that was described in a feature article in QST, September, 1992. Following the letter, David Herschberger, W9GR, responded. Mr. Herschberger acknowledged the potential problem and thanked Mr. Vogt for pointing it out. He advised that the problem has never yet occurred in practice, but described a complete solution for it for use if and when it does. _________ Title> TC2:Adapting the NU1N Voice-Control Program to the Yaesu FT-747GX Author> Lamendola, Angelo - KC2NT Source> QST Feb 1993, p. 77 Abstract> Relates a special adaptation of software described by NU1N in QST, August, 1992. Digest: Mr. Lamendola describes how he adapted the software described by B. Bergeron, NU1N in an article in QST, August, 1992, to control of his Yaesu FT-747GX. It required Mr. Lamendola to write a Basic language program, which he describes. A copy is available for down-loading on the ARRL Bulletin Board (203) 666-0578, identified as FT757.VC _________ Title> TC3:L-C Constants Author> Nashlund, Eric - NL7ZW Source> QST Feb 1993 Abstract> A simple formula for quickly calculating resonant frequency, capacitance, and inductance of tuned circuits. Digest> Mr. Nashlund has derived a formula that simplifies calculating the resonant frequency of a tuned circuit when the capacitance and inductance are known, or one of the parameters when the other parameter and the resonant frequency are known. His formula is: LC = 25330 / F^2 where: L = Inductance in microhenrys C = Capacitance in picofarads F = Frequency in megahertz ------------------------------------------------------------------------ HINTS AND KINKS (HK) Conductor: David Newkirk, WJ1Z Sr. Asst. Technical Editor _________ Title> HK1:Operate QRP With an Easy-To-Build Attenuator Author> Jeffery, Jay - WV8R Source> QST Feb 1993, p. 75 Abstract> A construction article for an attenuator to allow a modern transceiver to be operated with 5-watts output power. Digest> This hint relates to the fact that sometimes people with full- size transceivers want to operate QRP (reduced power). Usually, this requires output power no more than 5 watts. Many transceivers' output power adjustment cannot be turned down much lower than 10 watts. Mr. Jeffery shows a 6-dB. attenuator which can be connected between the transceiver and the antenna. The rig can then be set for 20-watt output and only 5 watts will reach the antenna. The attenuator is a very simple circuit. The output from the transceiver passes through three 8-ohm, 20 watt resistors in series. The output from the last resistor is connected to the center conductors of two coax connectors wired in parallel. One of these is attached to the antenna and the other to a 50-ohm dummy load. The resistors are available from Radio Shack as Part No. 271-120. It can be seen that approximately one-half the transmitter output power is dissipated in the resistors. The remaining power is split equally between the dummy load and the antenna; hence the antenna receives one-fourth of the total, or 5 watts. When left in the antenna, the circuit also attenuates received signals by 6-dB. but also attenuates the received noise equally. Hence the signal-to-noise ratio is unchanged and, in most cases, it makes a negligible difference in reception. However, the author also offers a diagram of a circuit that uses the push-to-talk line from the transceiver to actuate a relay that will remove the attenuator from the circuit during reception. _________ Title> HK2:Improved "Psycho-Regulation" and Arc Protection for High- Voltage Power Supplies Authors> Levin, Marty - W6BDN and Levin, Dan - N6BZA Source> QST Feb 1993, pp. 75-76 Abstract> Describes two modifications applicable to most high-voltage power supplies to improve performance: One to improve voltage regulation; the other to prevent damage to amplifier tubes from internal arcs. Digest> These authors show hints to improve two conditions that are common with tube-type high-power amplifiers. The first has to do with the voltage regulation of the power supply. Many amplifiers are put into "Stand-by" when not transmitting; this involves increasing the grid bias, removing the screen voltage, or otherwise cutting off current flow through the tube(s) but leaving the plate voltage on. With no current load on the supply, the plate voltage rises to a high level, stressing the filter capacitors and/or components in the amplifier. The authors propose to eliminate that condition by putting a high-power resistor in the ground-return of the rectifier circuit. The resistor reduces the d.c. output voltage to a low level. For transmitting, a relay controlled by the push-to-talk circuit in the transmitter shorts out the resistor. The resistor provides the additional advantage of greatly reducing the in-rush current to the filter capacitors when the power supply is first turned on, and thus protects the rectifiers from heavy current pulses. The second hint that the authors offer is to protect the amplifier tubes in case of a high voltage arc within the tube envelope. Should such occur, if it is not instantly extinguished, it will almost certainly destroy the tube. They propose that a fuse be placed in series with the high-voltage lead for a fail-safe solution to the problem. They suggest that a 3AG fuse holder be mounted on a plastic strip and the strip, in turn, mounted on ceramic spacers behind a hole in the front panel. The hole is to allow the fuse to be replaced easily, if blown. The editor has appended a note calling the reader's attention to the fact that this a very dangerous situation and extreme caution must by used when replacing the fuse under those conditions. The operator must be certain that power is off and all charge is drained off the filter capacitors before approaching that fuse-holder. _________ Title> HK3:Two-Meter Coaxial Antenna Author> Raffaele, Bob - W2XM Source> QST Feb 1993, p. 76 Abstract> Describes a quick and easy 2-meter antenna. Digest: Mr. Raffaele reminds readers that a coaxial antenna is a good one for use on 2-meters. For portable or occasional use, one can be easily and inexpensively made from a length of RG-58 feed-line and a short piece of RG-59 coax. To construct it, the user strips the outer jacket and most of the braid from the first 19-inches of the RG-58. This leaves 19-inches of center conductor and dielectric exposed. Then the builder must take a 19-inch piece of RG-59 and remove the braid, discarding the rest. The RG-59 braid is sufficiently larger in diameter than that of RG-58 that it will slip over the latter cable, outer covering and all. The builder slips the braid over the end of the RG-58, over the 19-inch stripped portion, and 19-inches further until the rear end of the braid comes abreast of the place where the braid of the RG-58 was cut off. Then a solder connection must be made between the two braids, leaving the length of RG-59 braid as a shield over the feedline. This completes the antenna, since the exposed length of RG-58 center conductor is the top half, and the outer shield is the bottom half of the coaxial dipole. The center of the dipole is the solder joint between the inner and outer braid. ------------------------------------------------------------------------ LAB NOTES (LN) Conducted by: Steve Ford, WB8IMY Asst. Technical Editor _________ Title> LN1:What Rig Should I Buy? Author> Ford, Steve - WB8IMY Source> QST Feb 1993, pp. 79-80 Abstract> Descriptions and comparisons of modern ham equipment. Digest> This is a two-page discussion in the form of questions and answers concerning the various attributes and characteristics of modern ham rigs. It is a good tutorial for newcomers, and an equally good check-sheet for old-timers, who may be shopping for new gear. Among the characteristics that the author explains and discusses at length are: i.f. filters, audio filters, notch filtering, pass-band tuning, double VFO's, noise-blankers, memories, computer control, general-coverage reception, antenna tuners, different operating modes, and many other factors involved in a purchasing decision. ------------------------------------------------------------------------ FEEDBACK (FB) _________ Title> FB1:QST November, 1992, p. 68 "Dipoles Above Real Earth" Author> Michaels, Charles J. - W7XC Source> QST Feb 1993, p. 78 Abstract> Corrections to equations; qualification of range of results. Digest> In the letter from Charles J. Michaels, W7XC, "Dipoles Above Real Earth", there is an extra parenthesis at the end of the numerator in Equation 1. In the definition of K, below the RI and XI equations, there is another extra parenthesis. It should read: K=120(ln(48Lf/d)-1). In his reference to "feed-point impedance" in the third paragraph, column one, it should have been: "I've developed a method of calculating the radiation-resistance component of feed-point impedance..." The length curve in Figure 3 becomes grossly inaccurate below 0.2 wavelengths. It should be ignored below that limit. _________ Title> FB2:QST December, 1992, p. 52, "An Inexpensive, Expanded-Range Analog Voltmeter" Author> Grebenkemper, John Source> QST Feb 1993, p. 78 Abstract> Corrections to schematic. Digest> The schematic should show a connection between the negative battery lead and the junction of R2, R3, and R9. Also, the unnumbered potentiometer below R4 is R5. ------------------------------------------------------------------------ NEW HAM HORIZONS (NHC) This is a monthly section in QST. It is comprised of a group of articles directed to the needs of and interests of new hams. _________ Title> NHC1:W1AW at the Flick of a Switch Author> Richey, Lee - WA3FIY Source> QST Feb 1993, pp. 56-57 Abstract> Construction article: a single frequency receiver. Digest> This is a construction article with full instructions for building a crystal-controlled, single-frequency receiver tuned to W1AW code practice transmissions on 80, 40, or 20 meters. Printed circuit boards or complete kits of parts are available from Matric, Ltd., RD #4 Box 240, Franklin, PA 16323. _________ Title> NHC2:Two-Meter FM Mountaintopping...Sort Of! Author> Brook, Dick - KJ1O Source> QST Feb 1993, pp. 58-60 Abstract> Hiking in Maine with a 2-meter HT. Digest> This is a story of a hike along the Appalachian Trail across about three-fourths of the state of Maine. The author carried along a 2-meter FM handheld rig with him to try to access repeaters while on the trail, but was only partially successful. He includes a number of suggestions for those who would be interested in following in his footsteps, to make their radio operation more successful than his was! _________ Title> NHC3:Beyond FM Author> Kearman, Jim - KR1S and Healy, Rus - NJ2L Source> QST Feb 1993, pp. 61-63 Abstract> Different types of operating activity on VHF bands. Digest> Most hams' VHF operations are limited to local 2-meter FM, primarily through repeaters. This article points out the fun that can be had using other VHF bands and modes. Specifically, CW and SSB operation is interesting and challenging on the 50, 144, 220, and 420 MHz. bands. The article discusses equipment, antennas, and operations. _________ Title> NHC4:The Doctor is IN Author> Various Source> QST Feb 1993, p. 64 Abstract> Questions and answers, general. Digest> This monthly feature comprises questions and answers about subjects of interest to newcomers. Questions answered this month regard cross band operation through a 2-meter repeater with link to 10-meters, load limitations of a power supply, strange signals heard on the radio, sunspot activity, using old radio gear, the use of languages on the air other than English, and antennas. _________ Title> NHC5:Falling in Love With Ham Radio for Less Than $200 Author> Gold, Jeff M. - AC4HF Source> QST Feb 1993, pp. 65-66 Abstract> Inexpensive ham activities. Digest> The author describes his experiences assembling a portable station small enough to fit into a back-pack, for a total cost of less than $200 including an antenna. Operating from his home base with only 3 watts output, he was surprised to work a dozen or more European stations within the first couple of hours. He relates the fun that he and his 9-year old son Danny, KD4HQV, have had with his portable station on several vacations to lakes, to the ocean beach, and hiking on mountain trails. ----------------------------------------------------------------------- GENERAL INTEREST ARTICLES (GI) _________ Title> GI1:Hurricane Iniki Rallies Amateurs Author> Ron Hashiro, Ron - KH6JCA Source> QST Feb 1993, pp. 19-22 Abstract> Public service activities. On September 11, 1992, Hurricane Iniki hit the island of Kauai with 165 mile-per-hour winds. The telephone links (carried by microwave) to Oahu and the rest of the world, and even the broadcast stations, were put out of action. For many hours, all communications with the outside world were disrupted, except through amateur stations. This article describes how Kauai amateurs, as well as their counterparts on Oahu and the other islands, distinguished themselves in providing public service when they were most needed. Local, state, and national authorities expressed their appreciation to the hams after the emergency was over. _________ Title> GI2:Classic Rigs and Amplitude Modulation: Friendly, Nostalgic Ham Radio Partners Authors> Courson, Paul S. - WA3VJB and Ickes, Steve - WB3HUZ Source> QST Feb 1993, pp. 43-46 Abstract> Operating with old equipment. Digest> There are a number of hams who enjoy working with old, vacuum- tube gear and AM phone operation. It is said that they tend to adopt an operating style "that yield a slower-paced and somehow deeper train of thought." This article is made up of anecdotes about some of the operators and a discussion of the equipment that many of them use. The authors report that AM activity is concentrated around the following frequencies: 160-meters Upper part of the band 75-meters 3.885 MHz. 40-meters 7.290 MHz. 20-meters 14.286 MHz. 15-meters 21.390 MHz. 10-meters 29.000 to 29.200 MHz. _________ Title> GI3:Ham Radio at Soviet Space Author> Dakin, Steve - WQ5N Source> QST Feb 1993, pp. 47-50 Abstract> Display of Russian space equipment. Digest> In June, 1991, the Soviet Union sent an exhibit of artifacts from their space program to Ft. Worth, Texas for display. Nearly 80 tons of apparatus and equipment of all kinds were set up at the Amon Carter Exhibit Hall for a six-month stay. The exhibit was called "Soviet Space". A group of local hams organized an amateur radio demonstration to coincide with the exhibit. With the enthusiastic cooperation of many companies and individuals, they established a station and manned it with volunteers at least 4-hours per day on weekdays and all day on weekends, for the entire period. It included a VHF/UHF setup, complete with antennas on an azimuth-elevation mount, able to track satellites overhead. Each time the Russian space station "Mir" passed over Texas when the exhibit was open to the public, if the astronauts were free from other duties, a QSO was established. The audio was put on the public address system, clearly audible throughout the hall. As the weeks and months passed, the Texas hams and the astronauts became great friends. Every QSO was thoroughly enjoyable to everyone, notably including thousands of visitors. The exhibit was a great success and more than 250,000 people went through it during its six-month term. _________ Title> GI4:Endurance - Is Geography the Only DX Dimension? Author> Mastroianni, Joe - AA6YD Source> QST Feb 1993, pp. 51-54 Abstract> Fantasy fiction. Digest: This "article" is fiction, a fantasy. It relates the story of a ham who was trying to work a DX station through a pileup when a solar storm caused a radio blackout. After all other signals had disappeared into the noise, he suddenly heard the voice of a British sailor asking for help. The sailor reported that he was stranded on Elephant Island, off the coast of Antarctica, and that the year was 1916. He did not have radio gear and, in fact, didn't know what the words meant. Instead, he was hearing the ham's voice in his head and speaking into space. After the sailor gave more details of the Antarctic expedition of which he was a participant, the ham looked it up in an Encyclopedia. He discovered that the stranded explorers were eventually rescued, so he was able to tell the desperate man that help was on the way. ------------------------------------------------------------------------