Digest of Articles - QST Apr 94 (Long - 46k)

Digest of Articles - QST Apr 94 (Long - 46k)

Post by W. E. Van Hor » Wed, 20 Jul 1994 22:26:48

DIGEST OF ARTICLES - QST April, 1994

Following are digests of articles printed in the April, 1994 issue of
QST.  Such digests are being prepared for each issue of QST, and posted
periodically.  Subsequent issues will be posted one per week until they
"catch up" to the current date in mid-1994, thereafter monthly.

It is hoped that other hams will volunteer to post similar digests of
the other ham technical publications such as QEX, CQ, 73, COMMUNICATIONS
QUARTERLY, RTTY JOURNAL, et al.  Especially desirable would be digests
of publications in other countries, such as the RSGB RADIO COMMUNICA-
TIONS and ham magazines in Europe, Japan, Australia, and other countries
around the world.  We English speakers would especially enjoy them if
they were translated into our language, but they would also be valuable
additions to the world's knowledge if they were posted in the language
of origin.  Who knows?  Some bi-lingual ham somewhere might translate
them into English and re-post them.

Worldwide communications are getting better and better.  The time has
come to make the world's ham press available to all hams throughout the
world!

The major value of digests is to give readers sufficient information to
decide whether to obtain a copy of the full text.  If any U.S. reader
wants a copy of an article in QST, please inquire of other hams in your
own neighborhood.  Many have collections of back issues.  Anyone who is
unsuccessful in finding a fellow ham with a collection should try every
library in the area, especially those at universities and technical
colleges.  If all else fails, a copy can be obtained from the ARRL
Technical Department, 225 Main St., Newington, CT 06111-1494 USA for a
fee of $3.00 per copy.  Remember, it is both cheaper and quicker to
obtain one locally.

Readers in most other countries can obtain copies from their own
national ham organizations, sometimes translated into their own
languages.
-------------------------------CUT HERE---------------------------------

COPYRIGHT NOTICE: Copyright to all the following material from QST
Magazine is held by the American Radio Relay League (ARRL), effective on
the date of issue.  Permission is granted for redistribution of the
following in its entirety, or in part, provided that this copyright
notice is not removed or altered and that proper attribution is made to
ARRL as publisher of QST, to the authors of the original articles, and
to W. E. "Van" Van Horne, W8UOF, author of this compilation.
                              _________

                          TABLE OF CONTENTS

       (line number in parentheses - counting from CUT HERE line)

TECHNICAL ARTICLES (TA)

TA1:Build Your Own LOWFER Transceiver                                 75
TA2:The Trigonal HF Beam                                             125
TA3:A Function Generator with a Frequency-Counter Digital Readout    180
TA4:The RingMaster Ring Detector                                     221
TA5:The Elkhart County Tone Alert                                    262

PRODUCT REVIEW (PR)

PR1:ICOM IC-707 MF/HF Transceiver                                    304
PR2:Solder-It Soldering Kit                                          369
PR3:Radioware SSTV Explorer                                          401

HINTS AND KINKS (HK)

HK1:Adding a Noise Filter Can Be Worse Than No Filter At All         446
HK2:An RF Sniffer Meter                                              471
HK3:Curing RF Noise in a Fluorescent Shop Light                      494
HK4:Speaker Connectors as Power Terminals                            507
HK5:A Spinner for Kenwood Tuning Knobs                               518
HK6:Using Computer Graphics for Equipment Construction and Repair    537
HK7:A Handy, Padded H-T Case                                         556

TECHNICAL CORRESPONDENCE (TC)

TC1:Automatic Antenna Tuners for Wire Antennas                       573
TC2:Sniff! Sniff! I Smell Line Noise!                                616

LAB NOTES (LN)

LN1:Where Am I?                                                      638

NEW HAM COMPANION (NHC)

NHC1:Packet Without Computers                                        675
NHC2:The Doctor is IN                                                701
NHC3:An INDESTRUCTIBLE Dipole for 10 Meters                          717
NHC4:A Climatological Analysis of the Dayton HamVention              739
NHC5:The SWR Obsession                                               777
NHC6:Do I Need a Linear Amplifier?                                   803

RADIO TIPS (RT)

RT1:The 10-Meter Band Plan                                           831

GENERAL INTEREST ARTICLES (GI)

GI1:Operating Backpack Portable                                      857
GI2:Reading Radio Fiction                                            870
GI3:Digital Signal Processing: The Final Frontier                    886
GI4:Electromagnetic Fields and Your Health                           912                                                                   1162

------------------------------------------------------------------------

TECHNICAL ARTICLES (TA)
                               _________

Title>TA1:Build Your Own LOWFER Transceiver
Author>Curry, David - WD4PLI
Source>QST Apr 94, pp. 26-31
Abstract>Operating in the 1750-meter band which does not require a
license.  Power input is limited to 1.0 watt and the antenna must not
exceed 15-meters in length (49-feet), including feeder.  Range of up to
200 miles is possible.  Includes construction information for a suitable
transceiver.

Digest>The subject of this article is the 1750-meter (160- to
190-kilohertz) band which is not, strictly speaking, an amateur band;
it is open to all without the need of a license.  Transmit input power
is limited to 1-watt.  In addition, the transmitting antenna is limited
to a total of 15-meters (49-feet) in length, including the feedline.

Mr. Curry indicates that almost any kind of an antenna will do if one
wants to transmit no more than one mile (1.6 km).  If "DX" operation
(several, to as many as 200, miles) is desired, a resonant vertical
antenna is necessary.  He recommends a vertical made of aluminum tubing
with a 12-foot (3.5 meter) diameter "top-hat".

For resonance, a large diameter, multi-turn loading coil must be
attached at the base and a minimum-length coax feedline should be tapped
across the first few turns.  The coil should be close-wound of number
18, or larger, enameled wire on a 6-inch (15-cm.) diameter form.  The
total number of turns should be determined by experimentation to
establish resonance at the desired frequency.

The author provides a schematic diagram and construction details for a
complete transceiver, which he calls "Model 893".  It uses 6 integrated
circuits, including the voltage regulator; receiving-type variable
capacitors, and several dozen other electronic parts, all readily
available from sources listed in the article.  He also recommends a
low-pass filter for the input from the receiving antenna to minimize
reception of noise and interference from strong broadcast band, and
other local signals.

On the 1750-meter band, common practice is not to use full amateur call
signs.  Three- or four-letter combinations are usually adopted; many
hams use the first and last two or three letters of their calls.

A kit of all parts except the enclosure and knobs is being offered by
the author for a price of $94.00, including USA shipping.  With the kit
comes a manual detailing the construction, and also information about
antennas, and operating hints.  For further general information, he
suggests that interested parties might want to join the Longwave Club of
America, 45 Wildflower Road,  Levittown, PA 19057.
                               _________

Title>TA2:A Trigonal HF Beam
Author>Bird,*** - G4ZU/F6IDC
Source>QST Apr 94, pp. 34
Abstract>Describes a switchable beam antenna made of wire.  It is
comprised of 3 dipoles with a common parasitic reflector behind them.
The radiation pattern has 3 switchable lobes, 120-degrees apart.

Digest>In this article, Mr. Bird shows the construction of a switchable
beam antenna made of three dipoles aligned as the legs of an equilateral
triangle, with a common reflector behind all three.  The beam is
switchable to three different directions, spaced 120-degrees apart
around the azimuth.

To understand the arrangement of the wires, it is necessary to draw an
equilateral triangle.  Then, from each apex toward the mid-point of the
opposite side, draw a line.  If done properly, the three lines will meet
at a common point at the center of the triangle.  Of each of the lines
just drawn, erase the portion between the common center point and the
center of the respective side.

Now, three lines join at each apex of the triangle.  Draw an insulator
in each of the three lines close to, but not touching, the apex.  Also
draw an insulator in the center of each side of the triangle.  The
drawing of the plan view of the antenna is now complete.

Feeders lead to each of the three center insulators in the sides,
representing the dipoles.  The "Y" made up of the three wires that join
at the center is the "trigonal" reflector which directs the beam of each
of the three dipoles, whichever is e***d.

On the 20 meter band, the author used a dimension of 33-feet
(10.06-meters) for each dipole; each leg of the "Y" was 17-feet,
10-inches (5.44-meters), measured from the center to the insulator; the
total distance from the center point of the triangle to each apex is
19-feet (5.79-meters).  Those dimensions, in feet, can be calculated for
any frequency by dividing a number (N) by the frequency in MHz, as
follows:
        For the length of the dipole, N=468
        For the length of each reflector arm, N=252.7
        For the total distance from center point to apex, N=269.1
To convert feet to meters: 1-foot = 0.3048 meters.

Accompanying the article is a plot of the radiation pattern of the
antenna on 20-meters when it is mounted 25-feet (7.6-meters) above
average ground.  It shows a rounded cardioid pattern with good
directivity and excellent front-to-back ratio.  The author reports that
he built such an antenna that showed a measured forward gain of nearly 9
dBi and a FB ratio of more than 34 dB.  The antenna analysis performed
using "Elnec" antenna software indicates about the same amount of
forward gain, but a FB ratio of between 22- and 25-dB, which is still
quite respectable for even a 3-element Yagi although this is only a
2-element design.
                               _________

Title>TA3:A Function Generator With a Frequency-Counter Digital Readout
Author>Spencer, Ben C. - G4YNM
Source>QST Apr 94, pp. 35-39
Abstract>Construction of an audio-frequency function generator with
integral frequency counter.  Functions available are sine, square, and
triangular waves.

Digest>One of the most important items of bench test equipment required
on an experimenter's workbench is an audio-range function generator
capable of generating signals of various waveshapes, including
especially sine and square waves.  Mr. Spencer has designed and built a
versatile unit capable of generating those two, plus triangular waves,
over a frequency range of 10-Hz. to 80-KHz.  For sine and triangular
waves, the range extends to 100-KHz.

The function generator circuit itself is contained in a single
integrated circuit.  In addition, a dual op-amp chip contains the
remainder of the active elements.  The addition of a couple dozen
resistors, a few capacitors, and some switches completes the entire
instrument.

The frequency counter is contained on a separate PC-board and uses 6
decade-counter chips, 3 dual-digit LED displays, and a few other
components.  The power supply is built on a third PC-board, and produces
+12 and -12 volts regulated output.

The author estimates that a constructor can probably duplicate the unit
for a total cost of $50, including enclosure.  Final adjustment requires
a voltmeter and an oscilloscope.  The article includes full
instructions.

No complete kit of parts for this project is available, although a set
of three PC-boards, etched and drilled can be obtained from FAR
Circuits, 18N640 Field Court, Dundee, IL 60118-9269.  The price is
$17.50, including domestic shipping.  A PC-board template package is
available from the ARRL for an SASE.  Address the request to Spencer
Function Generator Template, Technical Department Secretary, 225 Main
Street, Newington, CT 06111.
                               _________

Title>TA4:The RingMaster
Author>Rumbolt, Robin - WA4TEM
Source>QST Apr 94, pp. 40-42
Abstract>The advent of "Caller ID" by telephone companies defeats
private repeaters' secret telephone numbers.  Described is a device that
uses the "RingMaster " (TM) service, also available from phone
companies, to restore privacy to the private repeaters.

Digest>The device described by this article was designed to overcome a
severe problem that was occasioned by the introduction, in some areas,
of "caller ID" by the telephone companies.  Caller ID allows anyone who
subscribes to the service to be able to see the phone number of the
telephone where the incoming call originates.  This seemed to represent
a disaster for repeater operators who use secret phone numbers known
only by members of the club supporting it.  In its basic form, it would
seem to allow anyone with a Caller ID display to make autopatch calls to
themselves and see the repeater phone number.

In some areas, Caller ID can be blocked by using certain call
sequencing, but in the author's area, this is not allowed.  What is
allowed is a "RingMaster" (TM) service.  This allows several telephone
numbers to be assigned to one phone line.  The ring timing differs
depending upon the number used to call.  Dialing the main number causes
the phone to ring in the normal "2-seconds ON, 4-seconds OFF" sequence.
With the three special RingMaster numbers, there are two additional
special sequences.

The author has designed an electronic circuit that is programmed to
answer only a ring using one of the special sequences, specifically
sequence No. 1, which is "0.8-seconds ON, 0.4-seconds OFF", repeated
continuously.  If a would-be hacker should place a call to himself, the
Caller ID would display the main number of the repeater, but not the
special number.  The repeater would not respond to the main number.

The circuit is assembled on a single PC-board.  The input is
electrically isolated from the phone line by an optoisolator and logic
devices detect the proper sequence, which closes a relay that connects
the phone line to the autopatch.
                               _________

Title>TA5:The Elkhart County Tone Alert
Author>Drudge, Dennis A. - W9XD
Source>QST Apr 94, pp. 43-46
Abstract>Construction of an alarm system to operate in conjunction with
an amateur repeater to provide tone-alert alarms of severe-weather
situations.

Digest>In Elkhart County, northern Indiana, the organization that
maintains the repeater decided to develop a tone-alert system to notify
all members of severe-weather situations as they develop.  They designed
a very effective system which included the design of an alarm that all
members were encouraged to build.  Mr. Drudge describes the system and
gives construction information in this article.

The system, in operation, responds to either of two 3-digit DTMF
sequences, and also the Long Tone Zero (LiTZ) signal.  The latter is a
3-second zero tone used as a universal distress call on repeaters, with
the endor***t of the ARRL.  When actuated, the system sounds an alarm
for 5-seconds, switches the received audio to a speaker, and starts an
LED blinking.

A circuit diagram is included in the article.  The logic is embodied in
nine ICs plus a voltage regulator.  They include a DTMF decoder chip, a
4- to 16-line decoder, and several logic chips.  All parts required to
build the unit are readily available from a number of sources, several
of which are listed by the author.  He makes available a "partial kit",
made up of a PC-board, a DTMF chip, and a latching relay for $30.00,
including domestic shipping.  He estimates that the total cost of a
unit, including a case, should be less than $50.00

For those who want to do the whole job themselves, a template package
containing the double-sided PC-board pattern and parts overlay can be
obtained from the ARRL Technical Department Secretary, 225 Main Street,
Newington, CT 06111.  Enclose a business-size SASE and request the
Elkhart County Tone Alert System PC-Board Template.
------------------------------------------------------------------------

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

Title>PR1:ICOM IC-707 MF/HF Transceiver
Author>Ford, Steve - WB8IMY
Source>QST Apr 94, pp. 75-78
Abstract>Performance review of ICOM's latest "entry-level" MF/HF
transceiver.

Digest>This transceiver is ICOM's answer to the low-priced "entry-level"
rigs that are now coming onto the market.  It is a small unit that
provides most of the functions that even the most sophisticated modern
ones offer.  However, to establish a low price, some functions must be
omitted, and the reviewer discusses several.

The front panel is free of much of the clutter common on larger units,
but all the essentials are there.  There is a large Power rocker switch;
also a very large and well-designed tuning knob, an RIT knob, an AF
Gain/Squelch knob, and two tiny knobs for mike gain and r.f. power,
respectively.  Seven switches are to the left of the tuning knob: Tuner,
RIT, Tuning Speed, Preamp/Attenuator, Mode, Noise Blanker, and Scan.
The Mode switch steps through CW, USB, LSB, AM, and FM.  On the right
side of the tuning knob are four push-buttons that control the dual VFO
and Memory functions.

The unit is well designed for mobile use; unique in its class, it has a
speaker on the front panel facing the driver of an automobile.  Jacks on
the back panel are available to make connections for operating in
digital modes, and also to drive an amplifier.

The reviewer pointed out a number of limitations, some of which are
serious.  Especially in CW operations, there are a number of annoying
features.  One is the AGC; it is set either "Fast" or "Slow", and the
settings cannot be adjusted.  In "Fast", the attack is so slow that it
makes moderate to strong signals annoying.  Also, the CW tone is set at
a fixed 800 Hertz, which is uncomfortably high for many experienced
operators.

Digital modes are received in the SSB setting and the lack of narrow
i.f. filtering is "painfully evident".  The reviewer states that the
manual suggests a "workaround" method of using the CW i.f. filter for
digital operations, but it is clumsy, at best.  In SSB operation, the
reviewer missed having a VOX function.

The most glaring omission for the reviewer was the lack of a
manually-operated transmitter switch.  For a ham who uses a manual
antenna tuner, it is necessary to switch the rig into continuous
transmit mode while adjusting the tuner.  In absence of such a switch on
the front panel, the operator has to use the microphone push-to-talk
switch, or hold the CW key down, while tuning.

In all other aspects of transmitting, the rig performed very well,
indeed. Its frequency control is extremely stable, even from a cold
startup. All reports on the quality of the audio were good to excellent.

The performance of the receiver was found to be good in testing.  The
noise floor, with a 500-Hz. i.f. filter in use, was between -120 dBm.
and -138 dBm., depending upon frequency band in use.  Dynamic range was
111 dB. to 128 dB.; 2-tone third-order IMD dynamic range was from 90 dB.
to 87 dB.

To summarize, the reviewer said: "The IC-707 provides good basic radio
performance for new hams and veterans alike, on a budget."  The
manufacturer's list price for the IC-707 is $1032, without power supply,
antenna tuner, or any other optional features.
                               _________

Title>PR2:Solder-It Soldering Kit
Author>Gruber, Mike - WA1SVF
Source>QST Apr 94, pp. 78-79
Abstract>A kit allowing anyone to solder together many different
combinations of metals, including aluminum, stainless steel, and zinc.

Digest>This soldering kit is made up of a small butane torch and a
collection of solder-paste syringes.  The syringes are like hypodermic
needles and each contains a paste made of soldering flux mixed with
powdered solder.  Each is designed for a different metal or combination
of metals.  To tin or solder, one spreads the paste on the surface to be
wetted and heats it with the torch.  First, the flux, then the particles
of solder, melt and bond to the work piece.

Four different pastes are supplied.  The Aluminum paste is, perhaps, of
most interest to amateurs because of the great difficulty of soldering
aluminum.  The reviewer found that he had good results soldering
aluminum to aluminum, and also soldering aluminum to other metals such
as brass.

He found that he had to clean the surfaces to be soldered very
thoroughly, using steel wool.    He advises some practice on test pieces
before undertaking a critical soldering job.

In summary, the reviewer was impressed and found that the kit enables
one easily to solder "an unbelievably wide range of metals".  The
manufacturer is Solder-It, Box 20100, Cleveland, Ohio 44120.  The list
retail price for the soldering kit is 59.00.  Replacement syringes are
$6.00 each and a variety of tip attachments are also available.
                               _________

Title>PR3:Radioware SSTV Explorer
Author>Pagel, Paul - N1FB
Source>QST Apr 94, pp. 80-81
Abstract>Describes a hardware/software package that allows any amateur
with a transceiver and computer to receive SSTV.

Digest>The Radioware SSTV Explorer is a hardware/software package that
allows anyone with an HF receiver and DOS computer to receive SSTV
images.  Nothing else is required!

The package is made up of a floppy disk (either 3.5- or 5.25-inch size),
and a 60-inch cable.  The cable is terminated with a DB-25 connector on
one end and a 1/8-inch diameter, 2-conductor audio plug on the other.
The DB-25 attaches to the computer's RS-232 serial port; the audio plug
to the audio output of the receiver.  That, plus a 27-page instruction
manual, is all there is to it; the only electronic hardware required is
on a tiny PC-board that is inside the DB-25 connector!

For good results, the computer should contain a VGA display board able
to display at least 32,000 colors, and also a one-megabyte, or more, of
video memory.  Anyone equipped with that will be able to receive the
full range of SSTV images now being transmitted on the HF bands.

The software is quite complete and allows one to receive, display, and
save on disk, any images received.

The reviewer found the manual to be quite complete in giving full
instructions concerning the use of the software.  It enables one not
only to capture and save the SSTV images, but also allows them to be
edited.  After they have been received, one can invert, mirror, rotate
in 90-degree increments, zoom, remove all color, filter, and otherwise
manipulate the images.  The manual does not, however, contain any
technical description of the hardware or software, an omission that the
reviewer regretted.

The manufacturer is Radioware, 225 Stedman Street, No. 27, Lowell, MA
01851.  The list price is about $50.00.
------------------------------------------------------------------------

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

Title>HK1:Adding a Noise Filter Can Be Worse Than No Filter At All
Author>Shelhamer, Mark - WA3YNO
Source>QST Apr 94, p. 82
Abstract>Describes a condition in which a noise filter inserted in the
d.c. power leads, rather than eliminating it, actually causes an
increase of electrical noise in a car.

Digest>The author relates that he had problems with electrical noise in
his automobile AM/FM radio and, to try to eliminate it, he installed a
commercial noise filter in the d.c. power leads.  The result was a
negligible improvement.  Upon investigation, he found that the shield of
the antenna coax was attached to the radio chassis ground at one end,
and to the frame of the car at the other.  He realized that the
commercial filter blocks r.f. from flowing on either the positive or
negative d.c. power leads.  Hence, noise that otherwise would have been
grounded through the negative d.c. lead was blocked and flowed through
the coax shield instead.  This, then, was capacitively coupled to the
center conductor, and so to the antenna input of the radio.

When he removed the commercial filter and grounded the receiver ground
directly to the negative battery terminal, the noise was greatly
reduced.
                               _________

Title>HK2:An R.F. Sniffer Meter
Author>Hoyt, Emerson - WX7E
Source>QST Apr 94, p. 82
Abstract>Describes a very simple but sensitive meter to detect the
presence of r.f. energy in circuits.

Digest>Mr. Hoyt provides a schematic diagram, and also description, of a
meter that he has used to detect the present of r.f. in circuits of all
kinds, including antennas.  It is built from a small microammeter with a
germanium diode (1N34, or similar) attached to each meter terminal.  The
diodes are installed with polarity such that, if any current flows, it
will tend to drive the meter upscale.

He attaches a length of No. 18 bus wire, about 2-inches long, to the
free ends of both diodes, then twists them and solders them together at
the outer end to form a probe.  He slips a piece of insulating tubing
over the leads, leaving only the tip exposed.

He finds that this meter is a very sensitive detector of r.f. of any
frequency.
                               _________

Title>HK3:Curing R.F. Noise in a Fluorescent Shop Light
Author>Lee, Mitchell - KB6FPW
Source>QST Apr 94, p. 82
Abstract>A bypass capacitor cures noise from a fluorescent light.

Digest>Mr. Lee found that a new shop light in his home caused tremendous
noise that appeared on all HF bands from 160-meters, up.   He eliminated
almost all the noise by bridging a 0.22-mfd. metallized-film capacitor,
rated for use on 125-volt a.c., across the power lines at the point
where the cord enters the fixture.
                               _________

Title>HK4:Speaker Connectors as Power Terminals
Author>Bauer, Jeff - WA1MBK
Source>QST Apr 94, p. 82
Abstract>Speaker connectors can be used as d.c. power connectors.

Digest>Spring-loaded speaker terminals were noted in Hints and Kinks,
December, 1987, as good for plugging in crystals.  Mr. Bauer also finds
them useful as light- to medium-duty d.c. connectors.
                               _________

Title>HK5:A Spinner for Kenwood Tuning Knobs
Author>Nollet, Kenneth E. - K0EN
Source>QST Apr 94, pp. 82-83
Abstract>How a bent wire can convert a standard Kenwood transceiver knob
into a spinner-knob.

Digest>The author uses a Kenwood transceiver, yet likes the type of
tuning knob used on ICOM gear, among others, that provides a shallow
hole in the face of the knob into which the operator can poke a finger
and use it as a spinner.  He fashioned a comparable spinner out of a
piece of plastic-coated, heavy-gauge aluminum wire.  He bent the wire
into a small circle to act as a finger hole, then extended the length
just far enough that it could be bent over the edge of the knob as far
as the set-screw hole, and stuck it into that hole.  When he bent the
wire to form a snug fit over the knob, it held itself in place and acted
as an effective substitute for the hole cut into the knob itself.
                               _________

Title>HK6:Using Computer Graphics for Equipment Construction and Repair
Author>Whitsitt, Ronald V. - N5JSC
Source>QST Apr 94, p. 83
Abstract>Using common computer software to prepare labels for "homebrew"
projects.

Digest>Applying printed labels to the face of "homebrew" projects is
always a problem.  Mr Whitsitt gets good results using his computer and
a laser printer to print appropriate labels on paper,  He states that
almost any "paint" program running on a PC will be able to print
lettering, as well as arcs for meter scales, etc., to form attractive
labels.

After the label is printed on paper, he covers the paper with Scotch
Magic Tape (TM).  Then he cuts it to size with a hobby knife and glues
it onto the equipment using *** cement.
                               _________

Title>HK7:A Handy, Padded H-T Case
Author>Norman, Nona M. - N8CKS
Source>QST Apr 94, p. 83
Abstract>A padded oven mitt works well as a case for an H-T.

Digest>Ms. Norman needed a padded holder for carrying an H-T in her
briefcase.   She discovered that a padded oven mitt, commonly sold in
houseware stores, can be used as is, or else trimmed to shape and
resewn, to do the job.  For sewing, turn the mitt inside out, sew the
edges around the desired shape, and trim off the excess.
------------------------------------------------------------------------

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

Title>TC1:Automatic Antenna Tuners for Wire Antennas
Author>Belrose, John S. (Jack) - VE2CV
Source>QST Apr 94, p. 84
Abstract>Even though an antenna tuner may be able to tune a short whip
to resonance at a low frequency, it will not be an efficient antenna.
A high-Q, base-mounted loading coil will be much better.

Digest>This letter is a commentary on the article by Jeff Bauer, WA1MBK,
reviewing the SGC, Inc. "Smartuner" automatic antenna system tuning unit
(ASTU) in QST Nov 93.  In it, Mr. Bauer noted that he was able to tune a
15-foot piece of wire on 160-meters and expressed the opinion that as
little as 8-feet of wire could be used for frequencies above 3.3-MHz.,
"making a 102-inch CB mobile antenna More Than Sufficient for multi-band
mobile use".

In this letter, Mr. Belrose points out that such an antenna would be
extremely inefficient, largely due to losses in the ASTU itself.  He
reports a series of tests which show a graph of the effective output vs.
frequency over a range of 2- to 13-MHz. for a 20-foot whip antenna used
in two different configurations.  The first configuration is with a
large, high-Q, base-loading coil, and the other is with the same antenna
mounted on a boat with an ASTU inside the cabin.  A third antenna, a
small diameter transmitting loop, is also plotted for reference.

The report shows that the 20-foot whip with a proper base-loading coil
will deliver a signal only about 4-dB. below that of an isotropic
radiator.  The same whip operated with an inside ASTU, on the other
hand, produces a signal that is more than 15-dB. below isotropic.  When
he scales the results to estimate the performance of a 102-inch CB
mobile antenna on 80-meters, he finds the result to be off the scale of
the graph at a level of more than 20-dB. poorer than isotropic.  The
curve for the small transmitting loop shows performance between the two
configurations of the 20-foot whip.

Mr. Belrose also shows that any capacitance to ground in the antenna
circuit between the ASTU and the radiator, itself, is a source of
substantial loss of signal.  Even the capacitance across a feedthrough
insulator and a base-mounting insulator loses considerable power if it
is between the tuner and the radiator.   Only when the loading coil is a
part of the radiator, itself, are those losses eliminated.
                               _________

Title>TC2:Sniff! Sniff! I Smell Line Noise!
Author>Thorington, Lloyd - N0RQU
Source>QST Apr 94, p. 85
Abstract>Describes a hand-held Yagi antenna used for locating the source
of line noises.

Digest>This letter describes a portable 3-element Yagi antenna built by
the author for use in locating the source of line noises of various
types.  It is designed to operate at about 130-MHz.  It is constructed
of a piece of wood with 3 commercial "rabbit ears" TV antennas, spaced
appropriately as the driven element, reflector, and director of a
3-element Yagi.  The elements collapse against the stick for carrying,
but when opened up, very effectively identify the source of arcing atop
poles, or other noise-makers on power lines.

------------------------------------------------------------------------

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

Title>LN1:Where Am I?
Author>Gruber, Mike - WA1SVF
Source>QST Apr 94, pp. 86-88
Abstract>Description of Latitude/Longitude and grid locator position-
measuring systems.

Digest>This article is written in the form of questions and answers.
It is a fictitious conversation between a ham asking questions and an
unnamed authority providing the answers.  It explains how the earth is
divided by latitude and longitude designations, and also by the world
grid locator system.

The world of ham radio was divided into "grid squares" of the Maidenhead
Locator System at a meeting of hams in 1980.  Each grid square is one
degree of latitude by two degrees of longitude.  Grid squares are
indicated by two letters, dubbed the "field", and two numbers, called
the "square".  The squares are further divided into subsquares by the
addition of two letters after the grid square.  The subsquares measure
2.5-minutes of latitude by 5-minutes of longitude.  Various ARRL
publications and computer programs allow one to find the grid square and
subsquare for any location in the USA.

Very precise maps of the entire United States, which include elevation
above sea level as well as geographic features down to individual
houses, in some cases, are published by the U.S. Geological Survey
(USGS).  They are called Topographical Maps and can be obtained from the
USGS Map Distribution, Bldg. 810, Box 25286/Denver Federal Center,
Denver, Colorado 80225.  They can also be found, along with an index, in
many public libraries.
------------------------------------------------------------------------

NEW HAM COMPANION (NHC)

        The New Ham Companion is a regular section of QST. It features
articles of primary interest to newcomers to the hobby.
                               _________

Title>NHC1:Packet Without Computers
Author>Wolf, Fred - N3CSL
Source>QST Apr 94, pp. 64-65
Abstract>Using a "dumb terminal" for packet operation, instead of a
computer.

Digest>This article points out that a computer is not an essential part
of a station that can communicate via the packet mode.  It is entirely
possible to operate a packet station with a "dumb terminal" instead of a
computer.  Very large numbers of terminals were built and used to
communicate with central computers in office settings before personal
computers (PCs) became common on most desks.  Many are now surplus and
available for low prices.

The author describes an amateur packet station using a terminal, a
terminal node controller (TNC), and an amateur transceiver.  The
transceiver can even be an H-T.  

A station so equipped will be able to send and receive packet messages
as well as any.  There are certain other desirable functions, however,
that require a computer.  Among them are recording, editing, and
manipulating the text, driving a printer to print the messages on paper,
and others.
                               _________

Title>NHC2:The Doctor is IN
Author>Various
Source>QST Apr 94, p. 66
Abstract>Questions and answers of interest to newcomers.

Digest>The questions discussed this month include: how to obtain copies
of obsolete software that the manufacturer no longer supports; the
proper length of a 2-meter whip antenna; frequencies within a band on
which it is legal to operate CW; use of foreign languages by American
amateurs on radio; the fact that it is not legal to transmit amateur
radio from a commercial airliner; problems in computer operation when a
new board was plugged in; and how to use a Commodore 64 computer on
packet mode.
                               _________

Title>NHC3:An Indestructable Dipole for 10-Meters
Author>Bowles, Chester S. - AA1EX
Source>QST Apr 94, p. 67-68
Abstract>Construction of a simple and inexpensive 10-meter antenna.

Digest>This article is meant to demonstrate how simple it is to build an
antenna for 10-meters.  The author shows photographs and describes a
dipole that he built using 1/2-inch (12-mm.) galvanized steel electrical
conduit, a wooden dowel for an insulator, and hose clamps to attach the
two conductors of the coax cable feedline.  He supports the antenna by
attaching it directly to wooden supports, without insulators.
Presumably, he only operates it in dry weather!

In a sidebar, Steve Ford - WB8IMY, points  out that the 10-meter band is
not completely dead, even though sunspot activity is approaching the
minimum.  He advises that anyone interested should scan the band,
especially from late morning through early afternoon hours.  Even at the
bottom of the sunspot cycle, there will be sometimes when contacts are
possible on the band, even DX.
                               _________

Title>NHC4:A Climatological Analysis of the Dayton HamVention
Author>Friedman, Neil D. - N3DF
Source>QST Apr 94, p. 69
Abstract>Weather conditions at Dayton HamVentions are almost always bad!

Digest>The Dayton HamVention is the world's largest gathering of hams
and is held yearly in Dayton, Ohio, at the end of April.  Many thousands
of hams come from all over the world to view the exhibits of equipment,
which are held inside arena buildings, and also to browse the enormous
flea market which occupies every space of the large parking lots that
surround the facility.

Because the paved parking lots are entirely occupied, many visitors park
in temporary "lots" in the surrounding area that are actually open
fields.  Year-after-year, visitors have come to realize that the weather
conditions in Ohio in late spring are characterised by wide swings in
temperature and frequent rainfall, often heavy.  Old-timers tell many
tales of parking lots that turned to seas of mud, stranding many cars;
drenching rainfall accompanied by winds that blew down canopies and
tents; and of other such calamities.

The author has made a study of the climatological records and presents
bargraphs showing the range of temperatures and the frequency of
rainfall for each day of every HamVention that has been held for the
past 20 years.  His information shows that in only four years of the
twenty did no rain fall during any of the three days.  In only one year
did rain fall all three days; but rain fell in two out of the three days
about one-third of the years and at least on one day in the rest.
Temperatures have ranged from 30 degrees F. (-1 degree C.) to almost 90
degrees F. (33 degrees C.).

The author presents the information without stating any conclusions
except that he intends again to be present this year, and that he plans
to have with him clothing suitable for almost any conceivable weather
condition.
                               _________

Title>NHC5:The SWR Obsession
Author>Ford, Steve - WB8IMY
Source>QST Apr 94, pp. 70-72, 74
Abstract>There is no value in reducing SWR below certain levels,
depending on frequency and type of feedline.

Digest>In this article, the author attempts to put Standing Wave Ratio
(SWR) in proper perspective; and also to compare the two basic kinds of
feedlines in common use: open-wire and coaxial cable.

Many hams make a *** of obtaining SWR as close as possible to an
exact 1:1.  Usually it is a waste of time to struggle to lower an SWR
much below 2:1 because the reduction of energy loss in the feedline to
be accomplished would make a negligible difference in the perceived
signal strength at the remote receiver.

The author gives five hypothetical examples to illustrate typical
examples of performance.  All show that antennas fed with coax perform
poorly when the SWR is high, even at HF; and that VHF/UHF antennas
show severe losses with long runs of coax, even with low SWR.  Open-wire
lines, on the other hand, provide high efficiency with either long runs
or high SWR, or both.
                               _________

Title>NHC6:Do I Need a Linear Amplifier?
Author>Aurick, Lee - W1SE
Source>QST Apr 94, pp. 73-74
Abstract>Do not spend money on an amplifier until every other means of
improving signal strength has been used.

Digest>In this article the author takes a hard look at the benefits,
versus the cost, of a linear amplifier in a hamshack.  If an existing
station radiates 100-watts, an amplifier can be added to boost that
power to from 400-watts up to the 1500-watt legal maximum.  If, in a
given QSO, one receives a signal report of S-7, boosting the power to
400-watts would raise the strength to about S-8; going to the full legal
limit would raise it to S-9.

The cost of a 400- or 500-watt amplifier (new) would be of the order of
$800 to $1500.  To go to 1500-watts, the cost would be $2500 to $5000.
Individual hams must make up their own minds concerning whether the
benefits to be obtained are worth the cost.  No ham should commit to an
expensive amplifier until other means of increasing signal strength,
such as better antennas, have been thoroughly considered.
------------------------------------------------------------------------

RADIO TIPS (RT)

These are short items, scattered among the articles in the NEW HAM
COMPANION section.
                               _________

RT1:The 10-Meter Band Plan
Author: Anonymous
Source: QST Apr 94, p. 68
Abstract: Recommended frequency allocations.

Digest: Frequency              Service
        28.000-28.070          CW
        28.070-28.150          Digital modes
        28.150-28.190          CW
        28.190-28.200          New beacon subband
        28.200-28.300          Old beacon subband
        28.300-29.300          Phone
        29.300-29.590          Satellites
        29.600                 FM Simplex
        29.610-29.690          FM repeater outputs

        FM Repeater Pairs: (input/output)
        29.520/29.620
        29.540/29.640
        29.560/29.660
        29.580/29.680
------------------------------------------------------------------------

GENERAL INTEREST ARTICLES (GI)
                               _________

Title>GI1:Operating Backpack Portable
Author>Andera, Jim - WB0KRX and Sample, Bill - N0IET
Source>QST Apr 94, pp. 21-25
Abstract>The pleasures of taking radio gear along on hikes and climbs.

Digest>The two authors are midwesterners and enthusiastic outdoorsmen,
fishermen, hikers, and campers.  They are also hams and enjoy taking
radio gear with them on their backpacking hikes through the hills and
mountains of the midwest and west.

                               _________

Title>GI2:Reading Radio Fiction
Author>Lisle, Larry - K9KZT
Source>QST Apr 94, pp. 51-53
Abstract>A brief review of fiction written about radio operations.

Digest>This is a description of some of the fiction that has been
published about radio, or people involved in radio, down through the
years.  The author states that it was largely fiction that kept him
interested while learning the rudiments of radio when he was young.  He
concludes by suggesting that any radio club that has a program for
newcomers, especially ***agers, might well include some fiction to
e*** their interest.
                               _________

Title>GI3:Digital Signal Processing: The Final Frontier
Author>Moseley, Robin - WA3T
Source>QST Apr 94, pp. 54-55.
Abstract>April Fool's Day fiction.

Digest>Many years ago, every April issue of QST contained an article
written by the "famous inventor", Larson E. Rapp (pronounced: Larceny
Rap).  Each of these was a description of a new "invention" which
started out as a reasonably credible statement of fact and observation.
As the story went along, it became more and more unlikely until it
finally ended with a preposterous mechanism or circuit that performed
miraculous things, often repealing the laws of Physics.  This was QST's
way of celebrating April Fools' Day!

The present article describes the use of digital signal processing
(DSP), along with electronic neural networks, to build a machine that
would take a skull, such as one from an archaeological dig, analyze the
acoustic resonances in the bone, and use them to calculate what the
actual face looked like when the skull was covered with flesh and skin.

There is no editorial comment that indicates whether the author, Mr.
Moseley, is related to Larson Rapp.  But whether or not he is of the
same *** line, it is certain that he follows in the same tradition.
                               _________

Title>GI4:Electromagnetic Fields and Your Health
Author>Overbeck, Wayne - N6NB
Source>QST Apr 94, pp. 56-59
Abstract>Whether or not fears of damage to humans from radio waves are
valid, take reasonable precautions to avoid excessive exposure.
------------------------------------------------------------------------