Digest of Articles - QST Nov 94 (Long - 51k)

Digest of Articles - QST Nov 94 (Long - 51k)

Post by W. E. Van Hor » Thu, 22 Dec 1994 03:20:03

Following are digests of articles printed in the November, 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

       (Following are line numbers - counting from CUT HERE line)

TECHNICAL ARTICLES (TA)

TA1:An ATV Station for 915 MHz - Part 1: A Miniature 1.5-W ATV        81
        Transmitter
TA2:A Home-Brew Loop Tuning Capacitor                                132
TA3:Just Enough Radio - The SP-750 Spider Junior                     203
TA4:A Single-Board Superhet QRP Transceiver for 40 or 30 Meters      227

PRODUCT REVIEW (PR)

PR1:AEA SWR-121 HF Antenna Analyst                                   281
PR2:JPS SSTV-1 DSP Filter for Slow-Scan TV                           332
PR3:MFJ-1796 Half-wave Vertical Antenna                              372

TECHNICAL CORRESPONDENCE (TC)

TC1:A Practical, Compact, Multiturn Transmitting Loop Antenna for    421
        80 Meters
TC2:Eclipse-Enhanced HF Propagation                                  457

HINTS AND KINKS (HK)

HK1:An Experimental 1/2-W CW Transmitter                             496
HK2:Repairing Heat-Cycling Failures in VHF/UHF Rig Output Modules    515
HK3:Constant-Carrier AM for the Drake Twins                          542
HK4:Wrist Rest for Keyboard Operators                                566
HK5:Curing Intermittent Meter Operation in the Telex Tail-Twister    585
        T2X Rotator
HK6:A One-Switch Compact Loop                                        604

FEEDBACK (FB)

FB1:"An SWR Detector Audio Adapter" QST Jul 94                       626
FB2:"A Smart Charger for Nickel-Cadmium Batteries" QST Sep 94        636
FB3:"A Reevaluation of the Caron RF Impedance Bridge" QST Sep 94     649

NEW HAM COMPANION (NHC)

NHC1:The Doctor is IN                                                672
NHC2:A Fishing Tackle HF Station TO GO!                              686
NHC3:Hams 'R Us Kids Net                                             704
NHC4:A NiCd Never Forgets.  Or Does It?                              723
NHC5:Building and Adjusting Trap Dipole Antennas                     754
NHC6:The Repeater Eater                                              781

RADIO TIPS (RT)

RT1:Selective Calling                                                822

GENERAL INTEREST ARTICLES (GI)

GI1:The World's Greatest DXer                                        849
GI2:Hams of Ability                                                  864
GI3:The DCDXF/IARU International Beacon Network - Part 2             893
GI4:Exploring the Internet - Part 3                                  924
GI5:The Wire Antenna                                                 981
GI6:3Y0PI - The Peter I Island 1994 DXpedition                       997
GI7:In the Line of Fire                                             1013
------------------------------------------------------------------------

TECHNICAL ARTICLES (TA)
                               _________

TA1>An ATV Station for 915 MHz - Part 1: A Miniature 1.5-W ATV
        Transmitter
Author>Graf, Rudolph - KA2CWL and Sheets, William - K2MQJ
Source>QST Nov 94, pp. 23-29
Abstract>Construction details for an amateur TV transmitter using
discrete components.

Digest>This article describes a simple and inexpensive way to get onto
amateur TV (ATV). The selection of the "915-MHz." band (actually 902-928
MHz.) introduces a band that is "at the doorstep" of the microwave
spectrum, which is usually considered to begin at 1000-MHz.

The transmitter uses amplitude modulation (AM).  It produces a complete
NTSC video signal and a 4.5-MHz. FM audio subcarrier, both modulated
onto the r.f. carrier.  The entire transmitter is built in a tiny
cabinet, 2.5 x 4 x 1 inch in size (63 x 100 x 25 mm.) and its output is
about 1.5 watts.

The circuit uses a crystal-controlled oscillator at approximately
57-MHz. into a chain of four doublers; the output of the last doubler is
near 915-MHz.  Following, is a driver that feeds the final amplifier.
Audio input from a microphone, amplified by one transistor, controls a
voltage-controlled oscillator (VCO) at 4.5-MHz., producing an FM signal.

Video input from a camera, VCR, or other source, is amplified by a video
modulator.  The FM modulated signal and the video signal are combined
and used to modulate the driver transistor that impresses the combined
video AM modulation and audio FM modulation on the output signal.  

The construction is straightforward.  The completed unit can be adjusted
using only a VOM, a frequency counter capable of measuring 4.5-MHz. (up
to 1000-MHz., if possible), and a dummy load for which construction
instructions are included.  In addition, an oscilloscope, a spectrum
analyzer, and a dip meter, would be helpful though not strictly
necessary.

A photograph with the article illustrates two home-built corner
reflector antennas; one is used for the transmitter, the other with a
down-converter for reception.  At the end of the article, it is
announced that a companion down-converter for use with this transmitter
will be described in another article in a future issue of QST.

The authors report that, with corner-reflector antennas high and in the
clear, excellent picture transmission was achieved over paths of up to
15-miles (25-kms.), with the receiving antenna only 6-feet (2-m.) above
ground.  They feel that the range could easily be trebled if a
higher-gain Yagi antenna were used at heights of 30-feet, or more, at
both ends.
                               _________

Title>TA2:A Home-Brew Loop-Tuning Capacitor
Author>Jones, Bill - KD7S
Source>QST Nov 94, pp. 30-32
Abstract>A tuning capacitor having very low losses is made of
telescoping copper pipe with Teflon dielectric.   A motor drive allows
remote control.

Digest>In the last few years, miniature loop transmitting antennas for
use on HF bands have received a great deal of attention.  It is a
well-proven fact that they are capable of good performance when properly
made and tuned.

The key to success with a miniature antenna is to achieve exceedingly
low ohmic losses in the loop and its tuning capacitor.  The reason is
that the radiation resistance of a small antenna may be as low as a
fraction of one ohm; unless the resistance of the antenna conductor,
capacitor, and all solder joints is very low indeed, it may be higher
than the radiation resistance.  In that case, more than half of the
input power would be lost as heat.

In many ways, the most crucial component of the antenna is the tuning
capacitor.  Conventional variable capacitors made of aluminum and held
together with screws will not perform adequately.  To minimize the
resistance, every joint must be carefully soldered or welded.  A sliding
electrical contact of any kind is out of the question.

This article describes a capacitor, designed and built by Mr. Jones,
that overcomes most of the limitations of conventional capacitor design,
yet is easily constructed using home tools.  To avoid sliding electrical
contacts, it uses a split-stator design.  The completed design mimics
the slide of a trombone.  The "rotor", in this case, is an elongated "U"
shape, the arms of which are made of copper tubing that slide into
larger diameter copper tubes.  The bottom of the "U" is formed of a
short piece of tubing and two right-angle elbow fittings.   Sliding the
"U" farther into the two half-stators increases the capacity, and vice
versa.

The tubing used for the stators is 3/4-inch (19-mm.) ID copper water
pipe; the sliding portion is 1/2-inch (13-mm.) ID pipe.  The OD of the
half-inch pipe is 0.625-inches which, when centered inside the
0.750-inch ID of the 3/4-inch pipe leaves .0625-inch (1.6-mm.) clearance
for the dielectric of the capacitor.  If the resulting capacitor were
air-spaced, that small spacing would limit the breakdown voltage of the
air gap and hence the power-handling capacity of the antenna.  To obtain
a much higher breakdown voltage, and also an insulating slide to keep
the tubes concentric, the space is filled with Teflon.  Several layers
of a thin sheet of that material is wrapped around the slide members
until the diameter of the slide forms a smooth slip-fit into the stator.
Since the voltage breakdown rating of Teflon film is of the order of
1000-2000 volts per mil (.001-inch, or .025-mm.), the breakdown voltage
of this capacitor is at least 6000-volts.

Mr. Jones made his capacitor 10-inches (25-cms.) long, which produces a
maximum capacitance, with the slide fully inserted, of 56-pf.  This is
5.6-pf. per inch (2.2-pf. per cm.) of length, which figure can probably
be used as a design parameter for similar capacitors of different value.

This capacitor was built as an integral part of a loop antenna for
operation on bands from 10- through 20-meters.  The loop was formed as
an octagon of 3/4"-inch copper pipe, 3-feet (91-cm.) across.  The tube
forming the top side of the octagon was cut in the center and elbows
soldered in place to hold the stator tubes vertical.  The entire
capacitor was enclosed inside a plastic box fabricated from 1/4-inch
(6-mm.) thick plastic sheet.  Also inside the box is mounted a
reversible gearhead motor driving a threaded brass rod that acts as a
lead***meshing with a nut soldered to the base of the "U"-tube.  The
motor is controlled from the author's operating position so that he can
retune the antenna every time he changes frequency.
                               _________

Title>TA3:Just Enough Radio - The SP-750 Spider, Jr.
Author>Agsten, Mike - WA8TXT
Source>QST Nov 94, pp. 33-36
Abstract>Construction details of a single-frequency, crystal-controlled
QRP transceiver with 1-watt output, for either 80- or 40-meters.

Digest>In this article, Mr. Agsten describes what is one of the simplest
and lowest-cost transceivers capable of reasonable QSOs in the ham
bands.  It is a single-band crystal-controlled CW transceiver, and when
supplied with 14-volt d.c. power, it will produce 1-watt output and
provides QSK T/R switching.  Its frequency can be varied only by
changing crystals.

The receiver section uses direct conversion.  It has RIT and an audio
bandpass filter.

The unit can be built to operate on either 40- or 80-meters.  A complete
kit of parts, including a mini-telegraph key and earphone, but not
including the crystal and plastic case, is available from Lectrokit, 401
W. Bogart Rd., Sandusky, OH 44870.   The price is $38.50, including
domestic shipping.  The kit also includes a detailed assembly manual.
                               _________

Title>TA3:A Single-Board Superhet QRP Transceiver for 40 or 30 Meters
Author>Benson, Dave - NN1G
Source>QST Nov 94, pp. 37-41
Abstract>Construction details of a simple, but effective, CW QRP
transceiver that provides almost all the functions of a full-size rig.

Digest>Described is a transceiver design created by the New England QRP
Club as a club project.  The transceiver was named the 40-40 because it
was designed for 40-meters at a target cost to the builder of $40.00.
More than 200 of them have now been built successfully.

The receiver section is a bona fide superhet with a dual crystal i.f.
filter.  It contains a variable-frequency oscillator (VFO) with a tuning
range of about 40-KHz. on 40-meters, which is adequate to cover the part
of that band most useful for QRP CW activities.  As designed, the unit
does not provide an RIT function, but that can be added as an outboard
option.

The receiver circuit is straightforward and takes advantage of the
sophisticated ICs now available to put most of the functions of a
high-performance receiver on chips.

The receiver and transmitter sections use the same VFO, which operates
at about 3.0 MHz.  The maximum transmitter output is about 1.5-watts.
The entire transceiver is built on a single PC-board 2.8 x 4 inches
(72-mm. x 101-mm.). There are only two controls on the front panel:
tuning and gain.

The ARRL laboratory tested the author's transceiver and found that it
meets FCC requirements for spectral purity.  They also evaluated the
receiver performance and found a 2-tone dynamic range of 90-db. and a
blocking dynamic range of 115-db., remarkable for so simple a receiver.

A 30-meter version of this same transceiver is now being built.  The
circuits are the same except for the frequencies.  The 30-meter version
has a slightly narrower operating bandwidth, limited to about 25- or
30-MHz.

The author reports that feedback from a number of builders has been
highly favorable.  He, using it himself, has had ragchew QSOs all over
the US and also with a half-dozen European nations, all on the 40-meter
band.

A complete kit of parts is available for $50.00, including postage, from
Small Wonder Labs, 80 E. Robins Ave., Newington, CT 06111.  Included are
all required crystals, all onboard parts, wire for the toroids, and a
manual.  Be sure to specify either the 40- or 30-meter version.
------------------------------------------------------------------------

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

Title>PR1:AEA SWR-121 HF Antenna Analyst
Author>Ford, Steve - WB8IMY
Source>QST Nov 94, pp. 77-79
Abstract>Describes an antenna analyzer that sweeps a band of frequencies
and displays a graph of the SWR of an antenna.  It can also feed the
data into a computer for display and/or storage.

Digest>The Advanced Electronic Applications (AEA) Model SWR-121 Antenna
Analyst contains a microprocessor that synthesizes an r.f. signal,
limited to less than 4-milliwatts, sufficient to energize an antenna
with a measurable level of forward and reflected power.  Its internal
circuitry makes these measurements and displays the information in the
form of a graph on a small (about 2-inches x 3-1/2-inches, or 51- x
89-mm.) LCD display.  Two versions of the SWR-121 are offered: one for
HF (1- to 32-MHz.) and the other for VHF/UHF (120-175, 200-225, and
400-475 MHz.)

The instrument is hand-held.  On the top of the case is a coax connector
which is the antenna input terminal.  In addition to the LCD display,
the front panel contains a keypad that controls the instrument.

Most commonly, the unit is used to scan across a frequency range and
plot the SWR in the form of a curve.  The user sets the desired center
frequency and the sweep bandwidth, using the keypad.  Width can be
anything from zero (a single frequency) to as much as 22-MHz. on the HF
version.

Included in the instrument is a serial port and connecting cable through
which the instrument can be connected to an MSDOS or Windows computer.
Such a connection allows the user to save repetitive scans and display
as many as six at once, for easy comparison.  Also, they can be saved
permanently on disk.  By comparing measurements made months apart, one
can often detect gradual changes that may be occurring in an antenna.

The reviewer found some minor annoyances in operation.  For one thing,
if one is operating the instrument on internal AA batteries (8 are
required), they find that the operating life is distressingly short.
Another is that the graph that is plotted on the integral LCD display
provides calibration marks along the vertical axis that are not set at
integral numbers; the microprocessor automatically scales the
coordinates to cover the width of data obtained but assigns irrational
values to the scale divisions.  Consequently, it is well-nigh impossible
to read an exact value from any point on the graph.

The reviewer's summary calls the SWR-121 "probably the ultimate
antenna-measurement tool for amateur radio applications", but the price
rather stiff.  The manufacturer's list price for the HF unit is $399;
that for the VHF/UHF unit is $469.  Computer software adds another $75.
                               _________

Title>PR2:JPS SSTV-1 DSP Filter for Slow-Scan TV
Author>Taggart, Ralph E. - WB8DQT
Source>QST Nov 94, pp.79-81
Abstract>A single-purpose DSP filter for optimum rejection of
interference to SSTV reception.

Digest>Slow-scan television (SSTV) operating mode utilizes analog
single-sideband analog signals in the same frequency bands where SSB
voice is used.  Interference throughout those bands is a continuous
problem, and it is especially so on SSTV in which interference of all
types is permanently recorded on the image being transmitted.

Digital signal processing (DSP) is a very powerful method for making
precise filters capable of shaping the received audio spectrum, at will.
JPS has taken advantage of DSP technology and designed a filter system
specially optimized for SSTV reception.

The audio spectrum utilized by this mode uses the frequencies from 1100-
to 1300-Hz. and from 1500- to 2300-Hz. only.  The optimum receiver
filter would be one that passes only those frequency bands, and rejects
all others.  The Model SSTV-1 approaches that ideal very closely.

It is built in a compact enclosure about 6-inches wide, 4-1/4-inches
deep, and 1-3/4-inches high (152-mm. x 108-mm. x 44-mm.).  Being a
single purpose device, it has no complex assortment of adjustments or
controls and is very easy to set up.  The only controls are power ON-OFF
and filter IN-OUT.

The reviewer made many tests under operating conditions and also in the
laboratory.  He found that the performance is as advertised, and the
effectiveness for on-the-air conditions is quite striking.  He cites
cases in which, without the filter in use, the interference was
sufficient to block any transmission, at all - the screen was black -
but with the filter in use, a decent picture was received.

The manufacturers list price for the SSTV-1 is $160.  Any dedicated SSTV
enthusiast should seriously consider obtaining one.
                               _________

Title>PR3:MFJ-1796 Half-Wave Vertical Antenna
Author>Cain, James D. - K1TN
Source>QST Nov 94, pp. 82-83
Abstract>A simple and relatively economical miniature antenna for bands
from 2- to 40-meters, not including the WARC bands.

Digest>The MFJ-1796 is a miniature half-wave vertical antenna that
covers the 2, 6, 10, 15, 20, and 40 meter bands.  Being only 12-feet
(3.66-m.) in height, it can be called an electrical half-wave because
both ends are at high impedance and the feed line attaches at a low
impedance point between them; but it is far from a half-wave in length
on any except the 2- and 6-meter bands.

Any shortened antenna will suffer from two limitations: first, the
radiation resistance is reduced in proportion to the reduction in
length; second, the operating bandwidth is narrowed.  The low radiation
resistance means that much higher currents must flow to radiate a given
amount of power.  High currents mean higher resistance losses and heat
dissipation, hence reduced signal strength.  One should expect that the
signal reports that such an antenna will produce will be of the order of
1 to 3 S-units lower than that from a full-size dipole at a comparable
height.

As should be expected, on 40-meters the bandwidth over which SWR is no
greater than 2:1 is only 55-KHz. wide.  Although the limitations of
shortened antennas are real, whether they are important factors in
everyday amateur operation is up to the individual.  For rabid DXers,
nothing short of a 100-foot tower mounted multi-element beam will be
acceptable.  But for a great many hams whose interests are directed to
shorter-range activities, such antennas are very satisfactory
performers.  For them, the fact that the MFJ-1796 does not require
radials, does not occupy much space, and is not terribly expensive, will
make it appealing.

The reviewer found that the antenna required no more than two hours to
assemble and was relatively easy to erect.  Tuning it, however, was a
bigger job.  It required lowering the antenna to the ground at least a
dozen times before the tuning was complete; at that, he admitted that it
was still not optimally tuned - he just ran out of patience.

The manufacturer's list price is $200.
------------------------------------------------------------------------

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

Title>TC1:A Practical, Compact, Multiturn Transmitting Loop Antenna for
        80-Meters
Author>Jones, Jon K., M.D. - NO0Y
Source>QST Nov 94, p. 87
Abstract>A miniature loop antenna for 80-meters that provides relatively
good efficiency.

Digest>Many articles have been printed about miniature loop antennas
over the past several years.  Most of them have emphasized the need for
reducing ohmic losses to the absolute minimum to avoid severe losses of
transmitter power.  Mr. Jones describes a loop that he has built for
80-meters and the precautions he has taken to maximize its efficiency.

The antenna is rectangular in shape, 9-feet wide and 7-feet tall
(2.74-m. x 2.13-m.), and it contains 3-turns.  He made it of No. 10
copper wire and inserted a capacitor in the center of the bottom side of
each turn.  Initially, he made each capacitor from a length of RG-8 coax
cable; one side of the capacitor is the center conductor and the other
side the shield.  He tuned the loop to resonance at the frequency he
desired by t*** each capacitor a bit at a time, keeping them all of
equal length.  RG-8 coax has a breakdown voltage rating of 5000-volts
and it makes very good capacitors.  Nevertheless, after he had finished
tuning, the author replaced them with doorknob capacitors of equal
value.  No provision is made for retuning during operation.

The author calculated the theoretical efficiency of the antenna and
found it to be 9.2-percent.  Although this means that more than
90-percent of the transmitter output is lost as heat in the antenna, it
is substantially higher in efficiency than many such antennas that have
been described in the literature.  Using the antenna and his 100-watt
transceiver, he has had excellent results.  During the ARRL 1994 Phone
DX Contest, he worked 9 DX contacts, including Portugal and Hawaii, on
75-meters from his home in Kansas.
                               _________

Title>TC2:Eclipse-Enhanced HF Propagation
Author>Lewis, David K. - W2HMT
Source>QST Nov 94, pp. 87-88
Abstract>Results of a study of radio propagation on the 80- and 40-meter
bands during a recent annular eclipse.  Signals improve dramatically as
the moon's shadow passes over the earth.

Digest>On May 10, 1994, an annular solar eclipse was visible over most
of the United States.  The author used the opportunity to make a study
of radio propagation, before, during, and after the shadow of the moon
passed across the country.

Before the eclipse occurred, he carefully observed band conditions both
the day before, and also on the morning before the it began.  On May 9,
band conditions during the daylight hours on both 80- and 40-meters were
normal. He did not detect any propagation paths longer than about
350-kms. on On 80-meters, nor 700-kms. on 40.

On eclipse day, May 10, the 80/75-meter band was totally dead until the
moon's shadow came within radio range at about 1703 UTC.  At that point,
the author states: "...the band literally popped open."  Strong signals
from as far as 1350-kms. were heard, 10- or 20-dB. over S-9.

Conditions on 40-meters were similarly enhanced.  Signals of up to
20-dB. over S-9 were heard from as far as 1400-kms.  After the eclipse
was over, and the moon's shadow totally left the earth, there were still
numbers of strong signals, but the distances shrank to no more than
650-kms.

It is clear that radio propagation responds very quickly, indeed, to
changes in solar radiation.
------------------------------------------------------------------------

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

Title>HK1:An Experimental 1/2-W CW Transmitter
Author>Smith, Lew - N7KSB
Source>QST Nov 94, p. 84
Abstract>Describes a transmitter made from a single CMOS chip.

Digest>Mr. Smith's letter, including a wiring diagram and parts list,
describes a crystal-controlled oscillator made from a single CMOS chip,
a 74HC240 high-speed octal buffer.  One section acts as a crystal
oscillator, four sections in parallel form a power amplifier.  Three
sections are unused.  Output power is about 0.5-watts.

The unit should be operated with a controlled power supply voltage
between 7.8- and 8.0-volts.  The output circuit is a bandpass filter to
remove harmonics.  Component specifications are included for 10-, 15-,
and 20-meter operation.  The ARRL Laboratory has tested the unit and
verifies that its spectral purity meets FCC regulations.
                               _________

Title>HK2:Repairing Heat-Cycling Failures in VHF/UHF Rig Output Modules
Author>Gruenwald, John - K0BF and Stockton, David - GM4ZNX
Source>QST Nov 94, pp. 84-85
Abstract>Describes home repair of open-circuits caused by a broken
substrate resulting from excessive heat.

Digest>Both authors report success in home repair of out-of-warranty rig
failures caused by overheating of the output stages.  Mr. Gruenwald's
Kenwood TM-732 developed an intermittent failure to transmit.  He
removed the power amplifier module which is a gray block.  The cover is
easily removed if one pries open some small tabs.  Nine transistors
built on a thin ceramic base act in parallel as the amplifier.  The
ceramic had cracked, breaking a lead in a printed-circuit r.f. ***in
the driver stage.  He soldered over the break, reassembled the rig, and
it has been operating properly ever since.

Mr. Stockton reports similar problems that occur because many VHF/UHF
mobile rigs do not have sufficient heat-sink capacity to handle the load
of long ragchewing.  Usually breaks in the ceramic substrate can be
repaired by soldering one or more fine wire bridges over the gap.

The editor notes that manufactured rigs can often be repaired at home,
saving considerable time and money.  But this should be done only to a
rig for which the warranty has expired, for obvious reasons!
                               _________

Title>HK3:Constant-Carrier AM for the Drake Twins
Author>Thomason, Steve - WB4IJN
Source>QST Nov 94, pp. 85-86
Abstract>Describes a conversion for the Drake T-4XB transmitter to
improve the quality of the signal received by a remote listener.

Digest>The Drake 4B-line, as manufactured, used controlled-carrier AM.
This means that, in between words, the carrier dropped to as low as 1-
or 2-watts output.  That makes it difficult to copy using vintage AM
receivers.  The author modified his T-4XB transmitter so that the
carrier level never drops below about 10-watts output, making it far
easier to receive.

He did it by converting the rig's 6AU6A pentode modulator to a triode by
tying together the screen and suppressor grids to the plate.  Then  he
coupled the output to the screen of the 12BY7A driver tube through a
.01-uF. capacitor, screen modulating it.

He reports that the operating results are as he desired.  He finds it
very convenient to be able to switch instantly between SSB and good-
quality AM.
                               _________

Title>HK4:Wrist-Rest for Keyboard Operators
Author>Seaton, S. L. - K4OR
Source>QST Nov 94, p. 86
Abstract>Describes a simple wrist-rest for anyone operating a keyboard.

Digest>Mr. Seaton found it tiring to have to have to hold his fingers
above the keys of his word processor.  He found he could relieve the
stress by arranging a soft pad for his wrists to rest on.

He made the rest from a piece of "Polytherm" insulation, a plastic-foam
tube made to slip over a 7/8-inch (22-mm.) ID water pipe for thermal
insulation.  He cut the tube to a length appropriate for the width of
the keyboard and slit it longways.  He then slipped it over the edge of
a piece of 3/8-inch (9.5-mm.) plywood, and slid the plywood under the
keyboard. The resulting soft rest has made long periods at the keys much
less tiring.
                               _________

Title>HK5:Curing Intermittent Meter Operation in the Telex Tail-Twister
        T2X Rotator
Author>Doherty, Robert J. (Whitey) - K1VV
Source>QST Nov 94, p. 86
Abstract>Addition of ferrite beads prevents RFI from causing false
readings of the antenna direction.

Digest>Mr. Doherty was plagued with intermittent meter indications in
the position-sensing circuit of his rotator.  He discovered the problem
resulted from RFI; when he ran his amplifier at full power, r.f. pickup
in the control leads caused arcs and burned spots on the position-
sensing pot.  He solved the problem by adding ferrite beads on the two
wires at the pot.

The editor notes that Telex will incorporate the ferrite beads in all
units built henceforth.
                               _________

Title>HK6:A 1-Switch Compact Loop
Author>King, John H. - NH6ZF and Galindo, Antoine F. - AC6G
Source>QST Nov 94, p. 86
Abstract>Substitute a superior switching scheme for that described in
the Capon article in QST May 94.

Digest>Author Galindo points out that, in the article by Capon: "You
Can Build a Compact Loop Antenna for 30 Through 12 Meters", QST May 94,
the control circuit shown in the diagram with the article contains
independent switches for "Forward" and "Reverse".  Actuating both
simultaneously will place a dead short across the battery or power
supply.

Both authors King and Galindo suggest an alternative switching
arrangement using a single DPDT switch, with center neutral, to control
the drive motor that tunes the antenna.
------------------------------------------------------------------------

FEEDBACK (FB)
                               _________

Title>FB1:"An SWR Detector Audio Adapter" QST Jul 94
Author>Lones, Dain - KC6WZK
Source>QST Nov 94, p. 88
Abstract>Correction for Figure 1 of the subject article.

Digest>Figure 1 of the article, p. 24, should show on chip U2A, pin 15
should be connected to +5.0-volts and pin 8 to ground.
                               _________

Title>FB2:"A Smart Charger for Nickel-Cadmium Batteries" QST Sep 94
Author>Johnson, Bob - AA4L
Source>QST Nov 94, p. 88
Abstract>Correct an error in the diagram of Figure 2 of the subject
article.

Digest>On Figure 2, a 150-ohm resistor is misplaced.  The correct
connection should be between the emitter and the base of Q1.  Also, the
solution of Equation 4 is incorrect.  R(sense) should be 1-ohm, not
1000-ohms.
                               _________

Title>FB3:"A Reevaluation of the Caron RF Impedance Bridge"
Author>Camillo, Charles - W6TGK
Source>QST Sep 94, p. 88
Abstract>Correct four equations in the subject article.

Digest>In the article, four equations contain mistakes:
        In Equation 6, p. 29, the right side of the equation
                should read: I(2)X(R)
        In Equation 10, p. 29, the denominator of the fraction should
                read: X(R) - X(1)
        In Equation 19, p. 30, the denominator of the fraction should
                be: (C(1) - C(R)) + jwRC(1)C(X) ("w" stands for omega)
        In Equation 20, p. 30, there should be a subscript "U" on the
                "R" in the denominator, like the one in the numerator

These errors are typographical only, they do not affect the end results
described in the text.
------------------------------------------------------------------------

NEW HAM COMPANION (NHC)
                               _________

Title>NHC1:The Doctor is IN
Author>Various
Source>QST Nov 94, p. 66
Abstract>Questions and answers of primary interest to newcomers to ham
radio.

Digest>Quest
ions discussed this month include: non-contaminating coaxial
cable; antennas for use at low heights; switching transceiver input
between a modem and a microphone; waterproofing coax connectors;
problems of over-deviation in FM modulation; and problems of using DOS
programs in a Windows environment.
                               _________

Title>NHC2:A Fishing Tackle HF Station to Go!
Author>Capon, Robert S. - WA3ULH
Source>QST Nov 94, pp. 67-68
Abstract>Illustrates how the author packs his station in a tackle box.

Digest>In this article, Mr. Capon describes how he carries a complete
QRP station in a fishing tackle box.  The box contains a top
compartment and four drawers.  He carries a transceiver, battery,
solar-cell charge controller, SWR analyzer, paddle, and headphones in
the top compartment.  A large number of tools and miscellaneous items
fill all four of the drawers.  A solar panel, an Outbacker antenna
(disassembled), and aluminum foil for a counterpoise are carried
external to the tackle box.

The author does not state the total weight he ends up carrying!
                               _________

Title>NHC3:Hams 'R Us Kids Net
Author>Bernotas, Vince, III - N2WXE
Source>QST Nov 94, p. 69
Abstract>Describes a 2-meter net formed by kids, for kids.

Digest>The author is 11-years old.  On December 12, 1993, he started the
"Hams 'R Us Kids Net" in Plattsburgh, NY.  It is a 2-meter repeater net
that was designed to encourage kids to participate in ham radio.  The
local radio club gave him permission to use the club repeater for the
net one hour on Sunday evenings, starting at 1900 local time.

The author acts as net control and initiates each session by reading a
preamble, then accepting check-ins from kids under the age of 16.  After
a half-hour, check-ins are opened to ***s.  Then the ***s are paired
off with kids in partnerships, which many have found to be rewarding for
both partners.
                               _________

Title>NHC4:A NiCd Never Forgets.  Or Does It?
Author>Gruber, Mike - WA1SVF
Source>QST Nov 94 - pp. 70-71
Abstract>Corrects misconceptions regarding NiCd "memory effect".

Digest>"Conventional wisdom" has it that NiCd batteries are very prone
to a "memory effect".  Supposedly, if one never discharges such a
battery very far through use before recharging, the battery will
progressively recharge to a lower and lower voltage and will hold only a
fraction of its original charge capacity.  The purported way to overcome
this problem is to be sure always to discharge the battery completely
before recharging.

This article refutes that "wisdom".  Although such an effect can happen
under very unusual circumstances, it is rare.  What is common, however,
is the "voltage depression" effect that is caused by long, continuous
overcharging.  A battery suffering from that effect will charge to the
normal voltage but, after delivering power to a load for some period of
time, its voltage will rapidly drop between 0.1-  and 0.2- volts and
remain at that level until completely discharged.

Fortunately, even if a battery reaches this state, it is easy to correct
the problem.  All it requires is one or two complete charge/discharge
cycles; that is, to discharge down to a voltage 1.0-volts, then fully
recharge it.

One should not discharge NiCds below 1.0-volt if it can be avoided, as
shortened life may result.
                               _________

Title>NHC5:Building and Adjusting Trap Dipole Antennas
Author>Edwards, A. W. - K5CN
Source>QST Nov 94, pp. 72-73
Abstract>How to build and tune trap dipoles.

Digest>This article describes how to make, and tune, multi-band dipoles
made with traps in the "classic" manner.  This means a dipole, fed in
the center, with a pair of traps resonant at the highest frequency band
for which the antenna is to be used attached to the ends.  Next, short
pieces of wire are added to each end beyond the traps, and the wire
trimmed until the full antenna resonates at the second highest band
desired.  Another pair of traps, resonant on that band, are attached to
those wire ends.  This procedure is repeated until the lowest desired
band is reached, but no traps are added for that band.  The end
insulators are attached, instead.

To make it easy to adjust the wire length each time a new band is being
resonated, the author recommends the use of copper "split-nut"
connectors (available from industrial electrical supply houses).  The
wire being adjusted is cut in two pieces and the pieces are overlapped
for a considerable length, each pair of wires held in place by two
split-nuts.  Then effective length can be adjusted easily by sliding the
wires past each other.  After the proper dimension is found, the joint
can be soldered.
                               _________

Title>NHC6:The Repeater Eater
Author>Murphy, George - VE3ERP
Source>QST Nov 94, pp. 74-76
Abstract>Describes a 2-meter beam antenna for indoor use.

Digest>This article describes a 2-meter 2-element quad antenna built for
indoor use.  It is made of lightweight wooden sticks, made from pieces
of 3/4-inch (19-mm.) quarter-round molding, supporting the two quad
elements, made of wire.  The antenna is held together by glue and ***
bands and is suspended from the ceiling of an inside room.

The boom, like the spreaders, is a piece of quarter-round molding.  The
two spreaders for the driven element are 793.5-mm. (31-1/4-inches) long
and those for the reflector are 812-mm. (32-inches) long.  The boom is
560-mm. (22-inches) long.  Each of the four sides of the square driven
element is 524-mm. (20-3/8-inches) long; those of the reflector are
550-mm (21-3/8-inches).  The feed point is located in one of the
vertical sides of the driven element.

Each pair of spreaders is glued together as an "X".  At the points where
the spreaders cross, a cradle is formed for the boom to fit into.  It is
made of a 75-mm. (3-inch) long piece of right-angle wood molding, glued
perpendicular to the spreaders and fitted into the crotch of the "X".
The right-angle edge of the boom fits into the right-angle grooves in
the cradles of both elements, and is held in place with *** bands.
The spacing between the driven element and the reflector is adjusted for
minimum SWR.

The author soldered an SO-239 coax fitting into the wires at the
feedpoint, and enclosed it in a plastic 35-mm. film cannister.  The ends
of the spreaders that bear against the ceiling are fitted with *** or
felt furniture bumpers.  To aim the antenna in azimuth, one pulls the
whole antenna down a bit from the ceiling, turns it in the desired
direction, and releases it.  The *** band pulls it against the
ceiling where it is held in place by friction.
------------------------------------------------------------------------

RADIO TIPS (RT)
                               _________

Title>RT1:Selective Calling
Author>Ford, Steve - WB8IMY
Source>QST Nov 94, p. 73
Abstract>"Selective Calling" makes a transceiver respond only to calls.

Digest>Selective calling is a feature that is provided with most FM
transceivers.  This feature allows the rig to perform like a telephone;
that is it can be left "ON", monitoring a particular repeater, or
simplex frequency, but nothing will be heard unless someone specifically
calls.  In order to set it up this way, if the transceiver utilizes
DTMF, the operator must select a certain tone sequence.  If a calling
station starts by sending those tones (the same tones used by touch-tone
telephones), the receiver will be activated.

A different selective-calling scheme is called CTCSS, or PL (Private
Line).  It uses low-frequency sub-audible signals that are mixed with
the normal voice audio.  In most cases, the tones cannot be heard over
the air.  With CTCSS, only one tone is involved, and the calling station
emits that tone continuously for the duration of the conversation.  When
the tone ceases to be received by the called party's receiver, it goes
dead.
------------------------------------------------------------------------

GENERAL INTEREST ARTICLES (GI)
                               _________

Title>GI1:The World's Greatest DXer
Author>Cain, James D. - K1TN
Source>QST Nov 94, pp. 42-45, 83
Abstract>Describes the amateur radio activities of Bob Eshleman - W4DR.

Digest>This is a sketch of the ham career of Bob Eshleman - W4DR.  He
was first licensed in 1950, at age 14.  He is a dentist, a professor and
department chairman at the ***ia Medical College.

Mr. Eshleman has, apparently, won more awards for DX achievements on all
bands from 160- to 2-meters than any other person on record.  The
article contains details of his many accomplishments.
                               _________

Title>GI2:Hams of Ability
Author>Myers, Karen D. - KB7ZXE and Bridgman, Gurnee - W9NT
Source>QST Nov 94, pp. 46-48
Abstract>Describes amateur activities by, and for, handicapped people.

Digest>This article is made up of two short sketches.  The first, by Ms.
Myers, describes the ham activities of Cleve LeClair - N7IXG, who is a
quadriplegic.  Although he is confined to a wheelchair and must use a
ballpoint pen held in his mouth to write, he has become an expert radio
operator, avid DXer and contester, and was a valuable contributor to the
most recent Field Day activities as a member of the Radio Amateur
Volunteer Emergency Services (RAVES).

The second sketch is about the Courage Center's HANDI-HAM system.  It is
an activity that combines camping with learning and is open to disabled
people of all ages who want to become radio amateurs.  Included are
people with all types of physical disabilities: blind, deaf, unable to
write, etc.  Each fall, the organization puts on a one-week session with
the goal of helping each participant become a ham.

The camp is located on Lake George in Northern Minnesota, about
15-miles south of Bemidji.  The Educational Director of Courage Center
Headquarters, located in the Twin Cities, is Sister Alverna O'Laughlin -
WA0SGJ.  Many other hams volunteer their services and find the
experience of helping handicapped people reach their goals is very
rewarding.
                               _________

Title>GI3:The NCDXF/IARU International Beacon Network - Part 2
Author>Troster, John G. - W6ISQ and Fabry, Robert S. - N6EK
Source>QST Nov 94, pp. 49-51
Abstract>Describing new features to be added to the International Beacon
Network in Phase III.

Digest>The first installment of this series, in QST Oct 94, described
the current 14.1 MHz. worldwide beacon network, called Phase II.  That
network, which has been in operation for 15-years, is soon to be
expanded, technically upgraded, and will be called Phase III.  This
installment describes certain technical changes to be made.

The first is to overcome an operational problem that has plagued the
Phase II transmitters.  Namely, the problem of clock synchronization.
Each transmitter must know, to an accuracy of better than plus or minus
3-seconds, when to transmit.  The Phase III system will greatly speed up
the cycling and will force an even tighter tolerance on timing.
Consequently, the new transmitter installation will utilize a GPS
receiver that will provide time synchronization to an accuracy within
1-microsecond!

A second improvement is the addition of a microprocessor to control the
ALC bias voltage on each transmitter so that the power output will be
accurately controlled at the four different output levels: 100-, 10-,
1-, and 0.1-watts, transmitted in sequence.

When complete, the Phase III network will allow one to check for band
openings on all of the 5 bands from 20- to 10-meters within 3-minutes.
                               _________

Title>GI4:Exploring the Internet - Part 3
Author>Ehrlich, Scott - WY1Z
Source>QST Nov 94, pp. 52-54
Abstract>Use of Telnet, Anonymous FTP, and Archie on Internet

Digest>This installment describes several specific ways that information
can be obtained through Internet.  The first is through the process
known as Telnet.  When a person uses the Telnet process, they get
control of a remote computer and can command it to respond with specific
information just as if they were sitting in front that computer and
activating keys on its keyboard.  This is true in spite  of the fact
that the computer may be half a world away!

As an example, a ham can access the call sign database at the University
of Buffalo and get the same data that they would get by consulting a
Callbook.  To do that, one must have a connection that provides Telnet
software along with the link to Internet.  Then type: "telnet
callsign.cs.buffalo.edu 2000".  The server in Buffalo will respond:
"Connected to electra.cs.buffalo.edu".  At that point, one can type:
"help" and the list of available commands will be printed on the screen.
This shows how to look up a ham station by call sign, by city, by last
name, or by zip code.  The user then types the appropriate command, and
the information will appear on the screen.

The next function described is "anonymous FTP".  FTP stands for file
transfer protocol and, using it, one can download a specific file from
any remote computer that allows access in this manner.  It is called
"anonymous" because anyone can log into the computer without
restrictions; that is, one does not need to have an account on the
computer they are logging into.

The author of this article works with the Boston Amateur Radio Club and
maintains a list of files useful to radio hams on a server at Oakland
University in Michigan.  Its anonymous ftp address is: oak.oakland.edu.
Another site with many useful files is University of California, San
Diego.  Their address is: ftp.ucsd.edu.  To log into an anonymous ftp
server, when asked: "name:", the user responds: "anonymous".  To
"password:", they give their E-Mail address.

For people whose access to Internet is limited to E-Mail only, N8EMR
maintains a callsign directory, for U.S. calls only.  To utilize it, one

message must be: REPLY (user's E-mail address).  The second line: "CALL
(list one or more callsigns, leaving a space between them)".  Note: the
commands must be in all capital letters.

The third function described is the Archie utility.  This lets one
search for files and directories throughout the entire Internet system.
To utilize it, one types: "archie (subject)".

An example included in the article shows what happened when the author
entered: "archie hamradio".  The computer responded with a list of many
sites that contain directories named "hamradio".  Using that
information, one can then access each site listed using anonymous ftp.
                               _________

Title>GI5:The Wire Antenna
Author>Schmidt, Steven R. - KR4DL
Source>QST Nov 94, pp. 55-56
Abstract>Humor.

Digest>This is a humorous article describing the attempts made by an
unnamed ham to raise a wire antenna into the top branches of two trees,
using a slingshot, fishing line, and sinker.  After many frustrating
tries, he was unsuccessful.

The story may, or may not, have been an account of the author's personal
experience.
                               _________

Title>GI6:3Y0PI - The Peter I Island 1994 DXpedition
Author>Schmieder, Robert W. - KK6EK
Source>QST Nov 94, pp. 57-61
Abstract>Describes the DXpedition to Peter I Island near Antarctica.

Digest>This is an account of the DXpedition to Peter I Island, which is,
perhaps, the most isolated place on the face of the earth.  It is
located 280-miles (460-kms.) off the continent of Antarctica.

Nine amateurs risked their lives and spent a very large sum of money to
operate ham radio stations on that island for the first time in history.
They succeeded in logging 60,000 contacts at a cost near $4.00 per
contact!  This is the detailed story of their accomplishment.
                               _________

Title>GI7:In the Line of Fire
Author>Wall, Cynthia - KA7ITT
Source>QST Nov 94, pp. 62-63
Abstract>Sketch of Terry L. Johnson - KB5PRF, a forest-fire fighting
pilot.

Digest>This is a sketch of Terry L. Johnson - KB5PRF, who pilots
aircraft dropping fire-extinguishing chemicals onto forest and brush
fires.  He was one of the pilots who tried to save the lives of
firefighters in Colorado in summer, 1994.  The fire ultimately claimed
14 lives, but Mr. Johnson was able to help save 9 others by dropping a
load of chemicals on and around them, allowing them to escape.

Mr. Johnson is also an active radio amateur.
------------------------------------------------------------------------