Digest of Articles - QST Dec 94 (Long - 50k)

Digest of Articles - QST Dec 94 (Long - 50k)

Post by W. E. Van Hor » Wed, 25 Jan 1995 20:31:42

Following are digests of articles printed in the December, 1994 issue
of QST.  Such digests are prepared for each issue of QST, and posted
periodically.

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 Continues to Grow                      79
TA2:Exploring Intermodulation Distortion in RF Switching and Tuning  116
        Diodes
TA3:An ATV Station for 915 MHz - Part 2: A Tunable Downconverter     146
TA4:The Quick Powerhouse                                             186
TA5:Key Components of Modern Receiver Design: A Second Look          216
TA6:A Simple, General Purpose AF Amplifier                           263

PRODUCT REVIEW (PR)

PR1:Watkins-Johnson HF-1000 General-Coverage Receiver                294
PR2:ASAPS and CAPMAN: HF Propagation-Prediction Software for the     384
        IBM PC

TECHNICAL CORRESPONDENCE (TC)

TC1:Elevated Radials Work!                                           441
TC2:More Tower Safety Tips                                           470

LAB NOTES (LN)

LN1:Lightning Protection - Part 2                                    512

HINTS & KINKS (HK)

HK1:Curing "Wrong VFO" in the Yaesu FT-101E                          563
HK2:Plug-In Bypass Capacitor Stops Keying Glitches                   599
HK3:More on Slingshot Antenna Installation                           614
HK4:PTT Line Protection for Radios in Packet Service                 640

FEEDBACK (FB)

FB1:"A Function Generator with a Frequency-Counter Digital Readout", 661
        QST Apr 94

NEW HAM COMPANION (NHC)

NHC1:QSL Cards? Before You Write that Check...                       675
NHC2:The Doctor is IN                                                694
NHC3:The View from Above                                             706
NHC4:FM Contesting on Taylor Mountain                                751
NHC5:Building an HF Walking Stick Antenna                            770
NHC6:A "Universal"VHF/UHF Antenna                                    799

RADIO TIPS (RT)

RT1:International Third-Party Traffic - Proceed with Caution         830

GENERAL INTEREST ARTICLES

GI1:Exploring the Internet - Part 4                                  854
GI2:Monitoring the Shoemaker-Levy 9 Comet Impacts                    901
GI3:An Interview with Robert W. Jones, VE3CTM                        949
GI4:A Christmas Card                                                 970
GI5:Cuba: A Week to Remember                                         982
------------------------------------------------------------------------

TECHNICAL ARTICLES (TA)
                                _________

Title>TA1:An Inexpensive SSTV System Continues to Grow
Author>Vester, Ben - K3BC
Source>QST Dec 94, pp. 22-24
Abstract>Improvements and additions to the software SSTV system.

Digest>Since K3BC described his software SSTV system in QST Jan 94, a
considerable number of hams have gotten on the air with them. In
response to feedback he has received from users, as well as from his own
continuing experiments, he has made a number of additions and
improvements to the software.  This article contains descriptions of a
number of the software upgrades that he now makes available.

The first is to allow attractive "wallpaper" to be used as the
background for menu screens.  That is, a color photo or other digital
image can be displayed in the background with the words, or other ASCII
characters of the menu, superimposed over it.

Because picture files tend to be very large, a new SAVE routine has been
added to compress the image file as it is being downloaded.
Correspondingly, the TRANSMIT software has been reconfigured to handle
files in either the full or compressed format.

A number of new modes, involving both hardware and software, have been
added to the system.  One was developed to make use of new and more
sophisticated video cards that are now on the market.  Also, a software
mode that doubles the resolution in both directions has been added.
Other software routines have been included to make it possible to use
images not only from a TV camera, but also obtained from Internet sites,
from CD ROMs, or from other sources.

These and a number of other modifications which make for easier
operation are available on the ARRL Bulletin Board system at
(203) 666-0578.  They are all embodied in the file: VESTER_F.ZIP.  The
same file is being mirrored on Internet and on other BBSs.
                               _________

Title>TA2:Exploring Intermodulation Distortion in RF Switching and
        Tuning Diodes
Author>Thompson, Tom - W0IVJ
Source>QST Dec 94, pp. 25-27
Abstract>Lab tests of popular PIN diodes as substitutes for PN switching
types to reduce IMD in receivers.  Also a test of a tracking preselector
for the same purpose.

Digest>The three-part article by Rohde: "Key Components of Modern
Receiver Design" in QST May, June and July, 1994 made a very strong case
that the front ends of currently popular amateur transceivers create
excessive intermodulation distortion (IMD).  He showed that their
performance could be inexpensively improved by the substitution of PIN
diodes for the PN switching types currently used in selecting r.f.
filters.

W0IVJ has made extensive lab tests of readily available PIN diodes rated
for r.f. usage and, for comparison, a diode that contains a PIN
structure but was not designed for r.f. use.  These tests showed
conclusively that r.f.-rated diodes show greatly superior performance
compared to other components.

In addition, the author made a test to see whether a tracking
preselector utilizing PIN diodes to switch capacitors might be an
attractive alternative to the selectable bandpass filters that are
commonly used today.  A schematic diagram of his test circuit is
included.  His conclusion is that it would be a viable alternative.
                               _________

Title>TA3:An ATV Station for 915 MHz - Part 2: A Tunable ATV
        Downconverter
Author>Graf, Rudolph - KA2CWL and Sheets, William - K2MQJ
Source>QST Dec 94, pp. 28-32
Abstract>Construction details of a receiving downconverter as a
companion to the transmitter described in Part 1.  It converts received
signals on the 915-MHz. band to Channel 3 or 4 in the TV broadcast band.

Digest>The first part of this article, in QST Nov 94, described the
construction of the transmitter portion of the station. In this article,
the authors describe a receiving downconverter that is physically small,
easy to build, and designed for mounting outdoors on the antenna mast.
It converts the received signal from the 902- to 928-MHz. band to either
61.25- or 67.25-MHz. (Channels 3 or 4) so that it can be received on a
standard TV set.

The circuit uses two stages of r.f. amplification, a doubly-balanced
Schottky mixer, and a tunable local oscillator.  It is all built on a
PC-board 2-1/2 x 4 inches (63 x 100 mm.).

The authors previously stated that one of their goals is to familiarize
builders with the construction techniques usable at microwave
frequencies.  Accordingly, much of the article is devoted to detailed
instructions on coil winding, soldering, and other specialized
procedures.

Alignment of the finished unit can be done with only a signal source, a
TV set, a suitable power supply, and an analog or digital VOM.  The
signal source could be the transmitter described in the first
installment if sufficient precautions are taken to attenuate the signal
strength so as not to overload the receiver circuits.  However, if a
frequency counter and a signal generator covering the respective
frequencies of r.f. and i.f. were available, they would make the entire
procedure somewhat easier.

An etched and drilled PC-board and other parts are available from North
Country Radio, PO Box 53, Wykagyl Station, New Rochelle, NY 10804-0053.
                               _________

Title>TA4:The Quick Powerhouse
Author>Miller, Russ - N7ART
Source>QST Dec 94, pp. 33-37
Abstract>Construction of a high-power amplifier, with a quick-warmup
tube, for 2-meters.

Digest>According to the author's account, a major goal for designing and
building this amplifier was to obtain quick warm-up.  Most high-power
amplifier tubes require several minutes for the cathode to heat to
operating temperature; N7ART's design uses a new tube, the 3CX1200Z7,
which warms up within 10-seconds after power is applied to the filament.
His concern for such instant response is caused by his interest in
working transient sporadic-E propagation events.

The amplifier he built is capable of producing 1200-watts output on the
2-meter band.  His d.c. power supply delivers 3200-volts at 750-mils.
Operating at full power, the amplifier requires 85-watts of drive; d.c.
input power is 2400-watts and plate efficiency is 50-percent, so plate
dissipation is more than 1200-watts.

The unique features of the design are primarily mechanical.  The tube is
mounted directly on a sub-chassis, without the use of a tube socket.
The design of the output circuits is complex, both mechanically and
electrically.  Much of the design is borrowed from the RADIO HANDBOOK,
23d Edition, W. Orr, Editor, published by Howard W. Sams & Co., 1987.
Anyone contemplating construction of a similar amplifier should consult
that reference for details.
                               _________

Title>TA5:Key Components of Modern Receiver Design: A Second Look
Author>Rohde, Ulrich L. - KA2WEU
Source>QST Dec 94, pp. 38-42
Abstract>Description of a tracking filter used as a preselector in a
receiver front-end to eliminate the IMD caused by filter-switching
diodes.

Digest>This article is a follow-up to the three-part series that ran in
QST May, June and July, 94.  It is also a companion piece to the article
by Tom Thompson - W0IVJ, designated TA2 in this issue.  Dr. Rohde notes
that Mr. Thompson found Motorola MPN-3700 PIN diodes to work about as
well as the Siemens and H-P units, although they cost less than $1.00
each, a significant factor when one is replacing the 40-some diodes in
an amateur-band transceiver.

Described is an alternative means of improving the second- and third-
order IMD performance of receiver front ends: the substitution of a
tracking input filter to replace the bank of switchable bandpass filters
that are commonly used in today's transceivers.

Shown in photographs and also in a circuit diagram is the tracking
filter that is supplied with the Model ESH-2 receiver manufactured by
Rohde and Schwartz Company.  The assembly actually contains two filters,
one of which covers the range from 10- to 20-MHz., and the other 20- to
30-MHz., selected by a relay.  Each filter contains a single resonant
circuit that is tuned by a bank of paralleled tuning diodes.  Relay
switching eliminates completely the IMD caused by switching diodes, but
inserts tuning diodes in the circuits, instead.  To insure good
performance, Dr. Rohde designed the tank circuit using many tuning
diodes in parallel with a high C-to-L ratio.  The use of this filter
guarantees an intercept point of +30-dBm., or better.

A second alternative is a tunable input filter that uses a bank of
diodes to switch fixed inductors and capacitors in binary steps.  As an
example, seven capacitors with values of 1, 2, 4, 8, 16, 32, and 64 pf.,
switched in a binary sequence, would provide a net capacitance
(neglecting leads) of 1- through 127-pf.  A filter using that approach
is also illustrated in photographs and circuit diagrams from another
model receiver built by the same company.

Note is taken of the fact that the earlier series of articles found
the Ten-Tec Argosy VI to be at the low end of the second-order IMD
performance curve.  Since then, a simple modification has been made that
has raised the intercept from +40- to more than +60-dBm.
                               _________

Title>TA6:A Simple, General-Purpose AF Amplifier
Author>Spencer, Ben - G4YNM
Source>QST Dec 94, pp. 43-44
Abstract>Building a very small audio amplifier using two IC chips.

Digest>Described is a general-purpose audio amplifier, small enough to
be built easily into almost any piece of electronic equipment, even the
base of a microphone.  It features very high input impedance, very low
output impedance and ability to provide adjustable gain from 0 to 74-dB.
It will deliver up to 1-watt of output.

The circuit is made up of two ICs.  The first is a low-noise FET op-amp;
the second is an audio power amplifier.  The gain of the first stage is
switched in three steps: 0-, 20- or 40-dB.  A continuously variable pot
controls the power amplifier over the range 0- to 34-dB.  Operating
bandwidth is 16-Hz. to 30-kHz.  Two output connectors are provided; a
"LINE" output with a nominal impedance of 600-ohms, and a low-impedance
output suitable for driving a loudspeaker or other power-consuming load.
Power supply requirements are 12- to 14-volts.

Construction is simple and straightforward.  An etched and drilled
PC-board can be obtained from Far Circuits, 18N640 Field Court, Dundee,
IL 60118-9269, for a price of $5.50, including domestic shipping.
------------------------------------------------------------------------

PRODUCT REVIEW (PR)
        Conductor: Mark Wilson - AA2Z
                   Editor, QST
                               _________

Title>PR1:Watkins-Johnson HF-1000 General-Coverage Receiver
Author>Newkirk, David - WJ1Z
Source>QST Dec 94, pp. 76-79
Abstract>Review of the first receiver marketed to amateurs that uses
i.f. DSP for filtering, AGC, and demodulation.  Has many good features
but falls down badly in others.

Digest>Digital signal processing at audio frequencies became a factor in
Amateur Radio receiving within the last five years and was accepted
enthusiastically by the ham community.  Ever since, amateurs have been
speculating over how long it will be before DSP techniques will be
possible at i.f. frequencies so that all of the functions of i.f.
filtering, automatic gain control, signal detection and demodulation
will be done digitally.  The Watkins-Johnson HF-1000 is the first
product entry on the market to attempt that.

This expensive receiver, selling for some $4000, covers from 5-kHz. to
30-MHz., with 1-Hz. resolution of both tuning and front-panel display.
Its operating modes are AM, Synchronous AM (SAM), narrow-band FM, CW,
USB, LSB and independent sideband (ISB).  It provides i.f. filters with
58 different selectable bandwidths, a noise-blanker, i.f. notch filter,
AGC, squelch, and scanning.  Output connectors are available for
headphones, LINE, separate outputs for USB and LSB during ISB reception,
and speaker.  It can be computer-controlled via an RS-232 serial port.
The front end contains a switchable pre-amplifier.  The signal-level
meter is calibrated in absolute terms, dBm., and the reading is not
affected either by the presence or absence of the pre-amplifier or by
gain-control settings.

Front-end circuitry delivers the input from the antenna to a DMOS FET
passive mixer that up-converts to the 40.455-MHz. first i.f.  A 30-kHz.
roofing filter limits the bandwidth, after which comes some i.f.
amplification and variable attenuation.  A diode double-balanced mixer
converts the signal to the 455-kHz. second i.f., and an analog
multiplexer again converts it to the 25-kHz. third i.f., where digital
signal processing occurs.

Laboratory tests show that receiver noise floor, with a 300-Hz.
bandwidth i.f. filter in use, is -140 dBm. while the pre-amp is in
operation and about -133 with the amplifier off.  Blocking dynamic range
with the same i.f. filter measures between 107- and 112-dB. without the
pre-amp, 103- to 106-dB. with it in use.  Second-order IMD intercept is
+44-dBm. with pre-amp off, +46-dBm. with it in use.  Third-order IMD
intercept measured between 27- and 33-dBm. with the pre-amp off, 16- to
21- with it on.

Despite the creditable performance and the really striking new features
demonstrated by the HF-1000, the reviewer did not give it a good overall
rating because of several glaring deficiencies.  The first major flaw is
the performance of the AGC.  Its decay time can be switched to FAST,
MEDIUM, or OFF, but the attack time is 15-milliseconds, at least ten
times too long!  The result is that any strong signal or noise pulse
causes an extremely annoying "Pop" before the AGC has time to take hold.
Consequently, the FAST and MEDIUM settings are unusable.  Operating the
AGC with long decay time reduces the number of "Pops" that must be
endured, but is clearly not an acceptable condition for most reception.

The next problem in the design concerns passband tuning. The passband
can be adjusted in 10- or 100-Hz. steps over plus-minus 2-kHz., but only
in CW mode!  It is not available in the SSB mode.  This limitation can
be partially overcome if one listens to SSB in the CW mode by setting
the BFO offset to 0-Hz., then adjusting the passband tuning for optimal
rejection of the unwanted sideband; but this makeshift "work-around" is
hardly to be expected in a $4000 receiver.

Third, the notch filter in the HF-1000 is manually tunable plus-minus
10-kHz., and is very effective.  But many outboard DSP filters now in
use offer automatic heterodyne elimination of any number of interfering
carriers.  Why does not the HF-1000 make this function automatic?

For AM reception, synchronous detection is a great asset, and the
HF-1000 offers very high-quality SAM.  But it cannot do selectable-
sideband synchronous AM detection!  It is hard to fathom what possible
reason the designers could have had for omitting this obviously useful
feature.

The final failing described by the reviewer is the very low quality of
the audio produced by the receiver.  It is contaminated by several types
of digital noises, including high-pitched whines, medium-frequency
drones, and low-frequency thumps.  It seems clear that the manufacturer
did not exert the required effort to clean up the circuitry to eliminate
internal cross-coupling.

In summary, the presence of the Watkins-Johnson HF-1000 on the market
shows that the time when DSP receivers providing quantum leaps in
performance will be available for ham use is very near.  But it has not
yet arrived.
                               _________

Title>PR2:ASAPS and CAPMAN: HF Propagation-Prediction Software for the
        IBM PC
Author>Straw, R. Dean - N6BV
Source>QST Dec 94, pp. 79-81
Abstract>Computer programs to allow amateurs to calculate current
propagation conditions.

Digest>Some 20-years ago, a program for mainframe computers was created,
named IONCAP, to calculate probable HF propagation conditions based on
the solar activity and other conditions prevailing at the moment.  Ever
since, QST has run a series of graphs in every issue indicating the time
of day and the frequencies that are likely to provide successful
communication between the different parts of the USA and various
countries around the world.  Continuous improvements in the program have
been made and, by now, it makes reasonably accurate predictions.  But by
the time the magazine gets into the hands of readers, conditions may
have changed considerably in unpredictable ways.

Now the computing capacity of personal computers approaches, or
surpasses, that of mainframes that were available when IONCAP was
developed.  To take advantage of the widespread availability of great
computing power, two new professional-quality programs have been made
available to operating hams that make predictions nearly as good as
those of IONCAP.  Users can now calculate their own predictions using
currently available solar data obtained from WWV broadcasts.

One of these programs, CAPMAN, actually uses the same calculating
routines used in IONCAP and wraps a "shell" of user-friendly features
around it.  The other program, ASAPS, was developed in Australia and
uses somewhat different mathematical algorithms.

ASAPS is primarily designed for commercial broadcasters and
communication networks.  It calculates and reports a number of
propagation and operating conditions that are of importance to to them,
but of less concern to amateurs.   CAPMAN, on the other hand, seems to
be tailored more directly for amateur use.

ASAPS is priced at $275, whereas CAPMAN sells for $89.  The reviewer
tested the performance of both programs, using the logs of active
amateurs who participated in the ARRL CW DX Contest in February, 1994.
Both programs made projections that were quite accurately borne out by
the actual QSOs logged.  What slight differences there were between them
seemed to favor the performance of CAPMAN.  Judging from that
performance plus the greater ease of use and lower price of CAPMAN, the
reviewer recommends it as the better value for hams.

CAPMAN is produced and sold by Lucas Radio/Kangaroo Tabor Software, 2900
Valmont Rd., Suite H, Boulder, CO 80301, (303) 494-4646.  ASAPS' North
American distributor is Jacques d'Avignon, 965 Lincoln Drive, Kingston,
Ont. K7M 4Z3, Canada.
------------------------------------------------------------------------

TECHNICAL CORRESPONDENCE (TC)
        Conductor: Paul Pagel - N1FB
                   Assoc. Technical Editor
                               _________

Title>TC1:Elevated Radials Work!
Author>Bowen, Arlan - N4OO
Source>QST Dec 94, p. 84
Abstract>Results of a 160-meter antenna installation that substituted
four elevated radials for a large number of buried radials, with
superior results.

Digest>N4OO recently moved to a new location and needed to erect a
160-meter antenna quickly to participate in an operating event.  He was
able to get a 51-foot (15.5-meter) vertical into the air, but did not
have time to lay an extensive set of ground radials.  Instead, he strung
four 150-foot (46-meter) radials 10-feet (3-meters) above the ground.
Since the tower rests on an insulated base at ground level, each radial
is attached to the bottom of the tower and rises at a 45-degree angle to
a 10-foot high post located 10-feet from the antenna; from the posts
they run horizontally through the woods, supported by fence insulators
attached to trees.

Since the 51-foot vertical is only some 35 electrical degrees high, it
exhibits a large capacitive reactance at the base.  The author used a
large diameter coil to cancel the reactance, then tapped the feedline
partway up from the bottom, approximating the 50-ohm impedance point.

The results of his antenna installation have been outstanding,
substantially better than those he obtained from his 60-foot, (18-meter)
top-loaded, shunt-fed tower with buried radials at his former location.
                               _________

Title>TC2:More Tower Safety Tips
Author>Burkhart, Howard - KB6MYE
Source>QST Dec 94, pp. 84-85
Abstract>Safety precautions for working on towers.

Digest>This letter contains added comments to supplement the advice
written by Mike Cook - KC8EG in his "Tower Safety Tips", QST Aug 94,
40-41, as follows:

1.  All hard-hats should be held in place with chin-straps.  A side-
blow from a swinging boom can knock an unstrapped hat off one's head
with the first blow, and kill on the return swing!

2.  Cotton gloves are somewhat slippery; leather gives a safer grip.

3.  Be sure that goggles have an ANSI rating for impact protection.

4.  Always remember that there is usually no brake on a rope and pulley
being used to hoist heavy items up the tower.  NEVER stand, on the tower
or on the ground, underneath a load being hoisted.

5.  Rope that is used to tie a person to an object should be nylon,
7/16-inch (11-mm.) diameter for one person, or 1/2-inch (13-mm.) for two
people, using "kernmantle" type construction.  For other uses, nylon
rope with at least a 10:1 safety factor in rated strength should be
used.

6.  Take full account of the weather conditions.  If the day is hot,
make sure that climbers drink plenty of water, not caffeinated or
***ic drinks.  On cold days, beware of frostbite.

7.  Have someone available on the ground who is trained in first-aid,
and have first-aid supplies available.  If someone should fall, don't
move them unless CPR is necessary.  Get professional help first.
------------------------------------------------------------------------

LAB NOTES (LN)
        Conductor: Steve Ford - WB8IMY
                   Asst. Technical Editor
                               _________

Title>LN1:Lightning Protection - Part 2
Author>Tracy, Mike - KC1SX
Source>QST Dec 94, pp. 45-46
Abstract>Advice on methods for lightning protection.

Digest>This article continues a discussion of lightning protection for
an amateur station in a question and answer format.  The first advice
given is to consult experts for specific applications of protective
methods.  One should start with local government to learn about building
codes and safety regulations regarding antenna structures.  Also,
contact the ARRL Section Manager for reference to an ARRL Technical
Adviser or knowledgeable hams in the area.

Grounding materials, in general, should be made of copper.  Copper
flashing (coils of thin strip) is available from lumber yards.  Strip
copper, 1-1/2 inches (38-mm.) wide and at least 0.051-inches (1.3-mm.)
thick is the minimum recommended for ground connections.  Strip material
is better for grounding than wire of the same cross-section because of
lower inductance.  Ground rods should be at least 8-feet (2.4-meters)
long and should be either solid copper, or copper-clad steel.

Since antennas are most probably the highest metal objects on the
property, they are the most likely objects to be struck, so proper
grounding of the tower is essential.  One should establish multiple
paths for the current to reach ground, which means multiple ground rods,
buried radial copper wires, or both.  Splices in wire and connections
between wire and rods should use compression joints with ample contact
area providing copper-to-copper contact.  Do NOT use solder.

To prevent current from following the feedline into the shack, the line
must be grounded OUTSIDE the home or shack.  Any other conductors, such
as rotator control cables, that lead from the tower toward the shack
must also be grounded either directly or through a lightning arrestor.
Several types of lightning arrestors are made by a number of companies.

The only foolproof way to protect station equipment is to disconnect all
equipment from the antenna and also from the power lines when it is not
in use.  Further, the disconnection must be made outside the shack.  It
would not suffice to unscrew a coax lead from a transceiver, then leave
the disconnected coax lying near the rig.

The article ends by listing names and addresses of about a dozen
manufacturers of lightning protection equipment.
------------------------------------------------------------------------

HINTS AND KINKS (HK)
        Conductor: David Newkirk - WJ1Z
                   Sr. Asst. Technical Editor
                               _________

Title>HK1:Curing "Wrong VFO" in the Yaesu FT-101E
Author>Schick, Martin - KA4IWG
Source>QST Dec 94, pp. 82-83
Abstract>Modification of a transceiver to help avoid transmitting on the
wrong frequency when operating split-frequency.

Digest>Many DX stations operate split-frequency; that is, they transmit
on one frequency and instruct listeners to call on a different frequency
to prevent a pileup of callers from obliterating the DX signal.  A
common occurrence is that, when the pileup gets thick, one or more
stations call on or near the DX station's frequency, contrary to
instructions.  The author of this letter speculates that many such
transgressors are doing it accidentally and are probably ignorant of the
fact that it is happening.

His own Yaesu FT-101E contains one switch that controls whether the
external or internal VFO is used for receive or transmit.  It is a
4-position switch.  Operating properly on split frequency requires that
that switch be rotated one step clockwise and one counter-clockwise to
call and listen alternately.  In the "heat of battle", if the operator
by mistake turns the switch one step in the wrong direction, or two
steps in the right direction, from that point on the transmitter will be
on the wrong frequency until the operator notices the error, which
may take some time.

KA4IWG decided that his rig's "human engineering" was faulty; it makes
it too easy to do the wrong thing.  To reduce the likelihood of making
that mistake, he installed a separate toggle switch, mounted on the top
of the cabinet, and rewired the control switching network so as to make
a mistake most unlikely.

Circuit diagrams are included with the letter to enable one with an
FT-101E to duplicate the modification.
                               _________

Title>HK2:Plug-In Bypass Capacitor Stops Keying Glitches
Author>Van Horn, W. P. - K3CP
Source>QST Dec 94, p. 83
Abstract>A bypass capacitor eliminates problem from RF feedback.

Digest>Mr. Van Horn found that, when operating CW while running his 1-KW
amplifier, feedback into the keying circuit held it in the key-down
condition transmitting at full power until he shut it off.  Ferrite
chokes and beads distributed through the circuit did not help.

He found the solution to be a simple bypass capacitor across the keying
jack.
                               _________

Title>HK3:More on Slingshot Antenna Installation
Author>Ashworth, Dennis - K7FL
Source>QST Dec 94, p. 83
Abstract>Tips to save loss when shooting antenna support line over tree
branches.

Digest>Verifying the results of others who have reported success in the
use of slingshots to attach an antenna to a top branch of a tree, K7FL
offers some further details.  He ties a fishing sinker to a short length
of relatively low-strength line, as a leader.  This is, in turn, tied to a
heavier line on a reel.

Used in this way, if the sinker gets wrapped around a branch, he can
pull hard enough to break the leader without losing the entire length of
line.  Usually when he does so, the sinker and leader also fall to the
ground.  If they do not, the only loss is a lead sinker and a short
length of line.

He uses a 2- to 3-ounce (56- to 79-g.) teardrop sinker, 8- to 12-pound
(3.6- to 5.4-kg.) monofilament line as the leader, and 20- to 25-pound
(9- to 11-kg.) monofilament line as the main line.  He reports that he
can repeatedly and accurately shoot lines over his 100- to 125-foot (30-
to 38-meter) high fir trees.
                               _________

Title>HK4:PTT Line Protection for Radios in Packet Service
Author>Stahl, Jim - K8MR
Source>QST Dec 94, p. 83
Abstract>Means of eliminating damage due to transients.

Digest>On at least two separate occasions, VHF/UHF transceivers used as
packet cluster nodes were damaged by electrical storms that left the
transmitters locked up in the TRANSMIT mode.  In both cases, the
transceivers were made by Kenwood but were different models.

K8MR diagnosed the problem as having been caused by a voltage transient
on the push-to-talk (PTT) line.  He solved the problem by mounting a
5.1-volt Zener diode at the mike jack connecting between the PTT line
and ground.  The Zener will clip any transient greater than +5.1 or -0.6
volts.
------------------------------------------------------------------------

FEEDBACK (FB)
                               _________

Title>FB1:"Function Generator With a Frequency-Counter Digital Readout",
        QST Apr 94
Author>G4YNM
Source>QST Dec 94, p. 85
Abstract>Correction of mislabeled capacitors in schematic.

Digest>In Figure 3 of the referenced article, on page 38, C13 should be
labeled "C14", and C14 should be labelled "C15".
------------------------------------------------------------------------

NEW HAM COMPANION (NHC)
                               _________

Title>NHC1:QSL Cards?  Before You Write That Check....
Author>Bowles, Chester S. - AA1EX
Source>QST Dec 94, pp. 64-66
Abstract>Description of different types of QSL cards.

Digest>Exchanging QSL cards is a courtesy and a ham tradition that dates
from the earliest history of amateur radio communication.  There is no
reason that cards must be custom-printed, although most are.

One must never forget the real purpose that a QSL card serves: it
confirms a contact between two amateur radio stations.  The necessary
information is the call letters of the confirming station, the call
letters of the station contacted, the time and date of contact, the
frequency band and the communication mode used, a signal report, and the
name and return address of the sender.  Any card that contains those
pieces of information qualifies as a bona fide QSL card.
                               _________

Title>NHC2:The Doctor is IN
Author>Various
Source>QST Dec 94, p. 67
Abstract>Questions and answers of primary interest to newcomers.

Digest>Questions discussed in this issue include: simplex autopatches;
power requirements of TNCs; cleaning contacts on a rotary switch;
computer memory requirements for running TCP/IP; and strange signals
heard on 160-MHz.
                               _________

Title>NHC3:The View from Above
Author>Ford, Steve - WB8IMY
Source>QST Dec 94, pp. 68-70
Abstract>Capturing earth photos taken by amateur satellites.

Digest>Four of the amateur satellites that are in orbit carry cameras
that periodically take pictures of earth, record them in memory, and
transmit them to earth as digital packet data.

OSCAR 18 (Webersat) is a Microsat (tiny satellite).  Pictures are
snapped on command from the ground-based operators about once per week.
The images are then transmitted continuously on 70-cms. until the next
picture is shot.  Only a receiver is needed to capture these signals, no
transmitter is required.

To receive and display the images, one must be able to receive on the
appropriate frequency, must have a TNC with a phase-shift keying (PSK)
modem and a computer with display software. Because of the slow speed of
transmission, it is not possible to receive an entire picture file as
the satellite is making one pass overhead.  A minimum of two passes are
required.

The software required to decode the image file and put it into a form
that can be displayed on a PC is called "Weberware". AMSAT sells these
programs at reasonable prices.

Oscars 22, 23 and 25 operate differently.  Like Oscar 18, they take
pictures on command from the ground, but they communicate much faster,
at 9600-baud.

To capture a file from one of these, one must first download a Directory
listing the available pictures.  After selecting the one wanted, one
uploads a request and the satellite responds.  Hence, the receiving
station must be equipped both to receive the 70-cm. downlink and also to
transmit on the 2-meter uplink.

Complete information about how to go about this is available from three
sources: "Computer Processing of UO-22 and KO-23 Images", by Walter
Daniel - KE3HP, printed in the Jan/Feb, 1993 AMSAT Journal; "Webersat:
Step by Step", by Steve Ford - WB8IMY, in QST Dec 93, p. 63; THE DIGITAL
SATELLITE GUIDE, which can be purchased from AMSAT, PO Box 27,
Washington, DC 20044
                               _________

Title>NHC4:FM Contesting on Taylor Mountain
Author>Parmley, Bill - KR8L/7
Source>QST Dec 94, p. 71
Abstract>Contesting from a mountain top in Idaho.

Digest>KR8L/7, along with several other local hams, took transceivers
and antennas to the top of Taylor Mountain, 7000-feet (2130-meters)
above sea level. It is located near Idaho Falls, ID in grid square DN43.
They set up their station adjacent to WA7KRP's 2-meter FM repeater and
borrowed operating power from the site.  This article describes the
enjoyment that was had by all participants.

The author describes grid squares, which are a method of dividing the
earth's surface for identifying radio locations.  A grid square map is
available from ARRL Headquarters for $1.00.  Also, grid square
information is in the ARRL Operating Manual.
                               _________

Title>NHC5:Build an HF Walking Stick Antenna
Author>Capon, Robert - WA3ULH
Source>QST Dec 94, pp. 72-74
Abstract>Construction of an easily erected, portable antenna.

Digest>W3ULH and several hams planned a mini-expedition to set up a
temporary ham station on an island off the coast of North Carolina.
Most of the operation was planned to be on 20-meters, although they
wanted to leave open the possibility of operating higher bands. They
wanted an antenna that would be effective, easy to set up and take down,
and also easy to carry.  Accordingly, they built their own, a vertical
made of telescoping aluminum tubing.  The tubing used was 1-, 7/8-,
3/4-, and 5/8-inch (25-, 22-, 19-, 16-mm.) diameters.  The 1-inch tube
was cut to 4-feet, 8-inches (1.42 meters) length; the other three tubes
to 4-feet, 5-inches (1.35-meters).

For use, the tubing can be slid open and held in place with hose clamps,
to form a quarter-wavelength at any band from 10- to 20-meters; four
quarter-wave wire radials are laid on the ground and the antenna is fed
with coax at the base.  The vertical stands on a ***/plastic
insulator and is guyed with ropes at the top of the third section.  When
the tubing is collapsed, it is a convenient length to use as a walking
stick!

A description of the antenna, including a schematic diagram and parts
list, is provided.
                               _________

Title>NHC6:A "Universal" VHF/UHF Antenna
Author>Miller, Dave - NZ9E
Source>QST Dec 94, p. 75
Abstract>Description of a commercial discone antenna.

Digest>This article describes the discone antenna, which is a very
effective omnidirectional antenna that provides a low SWR load on any
frequency over a very wide range.  NZ9E bought a commercial version,
rated at 200-watts transmitting, on any frequency between 50- and
1300-MHz.

The basic discone shape is a broad-based cone pointing upward; a round
disk, nearly the same diameter as the base of the cone, is mounted
horizontally with its center on an insulator at the apex of the cone.
Most practical discones, like the author's, are made as "skeletons" of
metal rods that approximate the cone/disk shape.  The radiation pattern
is approximately the same as that of a ground plane antenna cut for
whatever frequency is in use.

The article finishes with a caution that it is necessary to use a
low-loss transmission line at these frequencies for any cable run longer
than a very few feet.
------------------------------------------------------------------------

RADIO TIPS (RT)

These are short items, scattered among the articles in the New Ham
Companion section, of interest to newcomers.
                               _________

Title>RT1:International Third-Party Traffic - Proceed With Caution
Author>Anonymous
Source>QST Dec 94, p. 70
Abstract>A list of the few foreign countries to which messages can be
sent.

Digest>Messages can be handled through amateur radio between the USA and
other nations only if there is an official Third-Party Traffic Agreement
between the countries.  Then, it is permitted only if it is non-
commercial and of a private, unimportant nature.

The article contains a list of the countries with whom the USA does have
such an agreement.  Most nations in the Americas (even Cuba) are on the
list; also Philippines and Australia (but not New Zealand).  A very few
in Africa, some Pacific Islands, and Jordan and Israel in the Mideast
complete the list.  No European nations are included, with the minor
exceptions of the ITU station in Geneva and special-event stations in
the U.K. having call signs with GB prefixes.
------------------------------------------------------------------------

GENERAL INTEREST ARTICLES (GI)
                               _________

Title>GI1:Exploring the Internet - Part 4
Author>Ehrlich, Scott - WY1Z
Source>QST Dec 94, pp. 47-50
Abstract>Describes software tools Gopher and The World Wide Web.  Also
explains Usenet Newsgroups.

Digest>This installment discusses two software tools, now
available to almost all Internet users, that make finding information
much easier.  They are the programs called Gopher and The World Wide
Web.  Finally, a description of Usenet Newsgroups is included.

Gopher is a utility program that is completely menu-driven. Using
Gopher, one can access computer resources located at almost every
college or university in the developed world, as well as at many, many
other sites.

When one enters Gopher, a menu is displayed listing sources, by name.
After one is selected, a menu of available resources there is presented,
and one can make selections from one after another menus, each narrowing
the field to reach the precise kind of information sought.  Once one
reaches the final item desired, selecting that item from the menu will
cause the actual document, or whatever is else is requested, to come up
on the screen.  It can be read, or downloaded to the user's own computer
memory, as desired.

The World Wide Web system goes even farther.  It allows one to search
for specific information, regardless of where that information may be
found.

Usenet newsgroups are discussion groups, like bulletin boards, devoted
to specific subjects.  As an example, there are about a dozen devoted to
various aspects of amateur radio.  In most groups, anyone is free to
post messages to ask a question, to answer a question asked by another,
or to make comments about one subject or another.

Each newsgroup has a name, which is its address, made up of a series of
qualifiers.  For example: "rec.radio.amateur.misc", for general ham
discussions, "rec.radio.amateur.antennas", for antenna talk, and
"rec.radio.shortwave" for SWL devotees.  There are many thousands of
newsgroups, on almost every conceivable subject, active on Internet
today, and more are being formed daily.  Anyone who has a question about
almost any imaginable topic will probably be able to find a newsgroup
where the question can be asked with a very great likelihood of getting
one or more replies.
                               _________

Title>GI2:Monitoring the Shoemaker-Levy 9 Comet Impacts
Author>Pressler, E. C., Jr. - W3ZXV
Source>QST Dec 94, pp. 51-52
Abstract>Hams build a corner-reflector antenna and monitor radio noise
at 22.210-MHz. from planet Jupiter during its collision with a comet.

Digest>In 1992, the orbit of the comet Shumaker-Levy 9 took it close to
the massive planet Jupiter.  The planet's strong gravity caused the
comet to break into many smaller pieces and distorted its orbit.  Soon
after, astronomers calculated that, on its next loop around, it would
collide directly with Jupiter.

In the process of breaking apart, some of the pieces of the comet were
slowed slightly so that, by early 1994, telescopes showed more than 20
fragments travelling in the same orbit, strung out in Indian-file.  It
became clear that they would strike the planet, one after the other,
over a several day period.

Radio astronomers knew that Jupiter emits radio waves under normal
conditions, and the question was raised whether the comet impacts would
cause detectable changes in that radiation.  W33ZXV and two friends,
Kurt Magni - NN3C and Walt Rauscher - N3EVV, decided to monitor Jupiter
at HF during the impact events.

They selected the frequency 22.210-MHz. as the channel to monitor, since
it is near the peak of the intensity of Jupiter's noise, and also
because it was well above the expected MUF and likely to be clear of
interference.  Then they built a corner reflector, using a half-wave dipole
centered in a corner made of chicken wire supported on a wooden frame.  A
22-Mhz. preamplifier was mounted at the feed point and the output
connected by coax to the author's Kenwood TS-940S transceiver.  A stereo
tape recorder was used to record the radio noise on one channel, and a
time signal from WWV on the other.  The amplitude of the noise was
converted to d.c. which was recorded on a strip-chart recorder.

The first fragment of the comet to strike hit at about 19:48 UTC, July
16.  The separation between Earth and Jupiter on that date caused a
43-minute delay in reception of the signal.  Precisely on schedule, at
20:31 UTC, the normal Jovian hiss suddenly changed to a "rat-a-tat"
sound that lasted for nearly 7-minutes.  At the same time, the chart
recorder showed a clear change.

The recordings and other data gathered was submitted to the Society for
Amateur Radio Astronomy, in Atlanta, Georgia to be combined with all the
other scientific data gathered during this unique event.
                               _________

Title>GI3:An Interview With Robert W. Jones, VE3CTM
Author>Rinaldo, Paul - W4RI
Source>QST Dec 94, pp. 53-54
Abstract>Interview with the new head of the ITU Radio Communications
Bureau.

Digest>Robert Jones is the new director of the International
Telecommunications Union's Radio Communication Bureau.  He is age 50 and
became a radio amateur at 16, which was the minimum age at which ham
licenses were given in Canada at the time.  He later obtained Masters
degrees in both engineering and business administration, and is still an
active ham.  He has held a number of administrative positions with the
Canadian government.

The ITU is the international organization that meets periodically to
negotiate treaties that establish the regulations controlling worldwide
radio transmission.  He will head the administrative staff at the ITU
Headquarters in Geneva, Switzerland.
                               _________

Title>GI4:A Christmas Card - With Apologies to***ens
Author>Silver, H. Ward - N0AX
Source>QST Dec 94, pp. 55-57
Abstract>Fiction.

Digest>This is a story, illustrated with cartoons, in the vein of
***ens' "A Christmas Carol".  The hero of the story is an old ham who
has refused to send QSL cards for many years.  The ghost of a dead ham
friend returns and convinces him to mend his ways.
                               _________

Title>GI5:Cuba: A Week to Remember
Author>Margelli, Janet - WA7WMB
Source>QST Dec 94, pp. 58-62
Abstract>A visit with Cuban hams.

Digest>WA7WMB, her husband Joe *** - N6CL, and Lauren Libby - KX0O
visited Cuba as guests of the Cuban Amateur Radio Association (FRC)
during the ARRL June VHF QSO Party.  In view of the highly strained
relations between our respective governments, the main concern of the
visitors was to foster people-to-people relations between hams.

They had a very pleasant visit, made many friends, and succeeded in
their purpose.
------------------------------------------------------------------------