file: uwave.txt   update: October 24, 1994

Getting on Microwaves
Zack Lau, KH6CP, ARRL Laboratory Engineer

The cheap way to get on microwaves is with 10 GHz Gunnplexers.  
The intrusion alarm sensors, while not optimized for 
communications, have been used for 83 mile contacts with horn 
antennas (conditions that day were very good).  More typical 
distances are 20 to 40 miles, line of sight.  Radar detectors 
often have 11.5 GHz Gunn transceivers inside that can be tuned 
into the amateur band. 
     In addition to the Gunn transceiver, you typically want to 
build an FM receiver to listen to other 10 GHz WBFM stations and 
a modulator to talk to other stations.  The p. 32-45 of the 1993 
ARRL Handbook describes how to hook 88-108 MHz FM radios to act 
as IF receivers. Page 32-54 of the same book shows how to 
modulate a Gunn diode with an LM317 regulator.  Modulating the 
supply voltage allows even the cheapest Gunn transceivers to be 
used.  They lack varactor diodes used for modulating expensive 
units.

The disadvantage of this system is that some groups insist on 
using a 30 or 33 MHz IF, none of which are compatible with each 
other or an FM radio IF.  They are either using modified FM 
radios or distance measuring devices known as Telurometers.  The 
latter was made by Pye Ltd of Cambridge in the UK and apparently 
has been available inexpensively in Canadian and Australian 
surplus stores.  Also, you may wish to have a pair of units to 
insure that you have the proper offset to work anyone else in a 
group.  Two gunn units on the same frequency will not be able to 
work each other.  They have to be offset by the IF to work 
properly.  Thus, one typically sets one unit to 10.25 GHz and the 
other to 10.28 GHz if one has a 30 MHz IF.  This is the most 
common choice of frequencies.

Varactor tuned Gunn transceivers are also available.  These have 
been selling for $66 from

SHF Microwave Parts Company
7102 W. 500 S.
La Porte IN  46350  does not deal by phone.
They also have a variety of used and new Gunn transceivers for 
$20 and up,
as well as related parts.

The varactor will let you tune to a variety of offsets., though 
you will need an FM receiver or receivers that will handle the 
different intermediate frequencies.

This is the cheapest approach known.  One activity center for
30 MHz IF Gunnplexers is in Northern Vermont/VE3.  If you don't 
live near an activity center, you might consider starting your 
own.  One way to find out about such centers is to look at the 10 
GHz contest listings.

However, the other approach is to use SSB/CW, which makes non-
line-of-sight contacts much easier, though this approch is much 
more costly for most people.
 
In the Northeast, one of the stumbling blocks to promoting 
microwaves has been the reliance on 2 meter SSB/CW.  Why?  It turns 
out that 2M SSB/CW is the most effective way of coordinating 
microwave activities among distant stations.  FM repeaters are an 
obvious solution that doesn't work.  Some people don't appreciate 
extended communications on "their" repeater.  Even simplex 
doesn't always work, as I've been reminded that some group 
intends to use 146.55 MHz in a few hours.  Aside from the social 
problems, there remains the fact that FM is often a poor mode for 
coordinating schedules.  If you are in the middle of everything, 
such as on Mt Greylock FM might actually be preferred.  But 
stations far to the North and South might find themselves 
"locked out" due to the capture effect associated with FM (weak 
signals are completely gone while a strong station transmits).

One possible solution is to plan your schedules ahead of time and 
stick to the microwave bands.  This may not work if the roads to 
the hills are as deceptive as some CT roads.  You see West Peak's 
Castle on your right as you get off exit 4 of Rt 691 west.  But, 
to get there, you need to take a pair of lefts!  People who have 
been there before have been known to take an extra hour to get 
there.

So why don't I just buy a 2 meter SSB rig?  The two current 
options are the Yaesu FT-290R Mk II and the Kenwood TS-751A, 
which are fine radios except for there cost, which is usually 
over $500.  What about a used one?  Surprisingly expensive, often 
selling for around $400.  Older base/mobile rigs such as the Icom 
IC-251 and the earlier Yaesu's can sometimes be had for $250, but 
these are pretty rare.  The IC-202 can be had for as low as $150, 
but finding one for sale is quite difficult in metropolitan 
areas.

A possibility is to build your own SSB/CW 2M SSB radio.  January 
and April 1993 QSTs show much how to build a low power (2 
milliwatt) transceiver.  The VHF/UHF DX Book describes a 2 
meter transverter.  The transmit stages of this transverter could 
be added onto the transceiver to get 10 watts of RF output.

Finally, it is possible to call CQ on 1296 and 903 MHz if you
are in an excellent spot.  However, merely being on the highest 
hill around for hundreds of miles may not qualify.  Just as 
important is having people listen in your direction.  The 
difficulty is many people are using antennas with high gain, and 
may only be able to look at 15 to 30 degrees of the azimuth at a 
time. As a result, people have gone to great spots and not worked 
anyone, because nobody pointed their beams that way.

Down East Microwave sells a line of transverter kits for 432 to 
5760 GHz.  
Box 2310 
Troy, ME  04987
phone 207-948-3741   fax 207-948-5157


Microwave Bibliography and sources for microwave components.
Zack Lau, KH6CP, Internet: zlau@arrl.org

903 MHz 

144 MHz IF transverter July 1991 QST p.25
20 mW output, under 4 dB NF.  28 MHz IF operation
is possible if tighter filters are used.  Unfortunately,
such filters normally require tuning or a precision 
machine shop.  Precision teflon board filters are also 
possible, except that nobody has done the work necessary.
Ordinary G-10/FR-4 is not made to high tolerances, so 
precision work with this involves adapting the design to
each production run of board.

Recommended way of getting to 10 watts on this band
is to buy a hybrid module, such as the Hitachi PF0011
(DEM), and hook it up according to the data sheet.
DEM also sells kits.  If linear operation in necessary,
make sure your hybrid is linear.  Many class C hybrids 
are available, though the newer ones tend to be linear 
to allow the power to be controlled.

125 watts, 10 dB gain.  April 1988 QEX Two 7289s on 
903 MHz.  An air cooled amplifier that is rather 
complex mechanically to build.  It is assumed that the
builder knows how to build the amplifier in the March
1970 issue of Ham Radio for 23 cm.

1296 MHz

144 MHz IF transverter ARRL Handbook p 32-15.  Boards are 
available from DEM.  Unfortunately, board artwork is not 
available from the ARRL.

28 MHz IF transverter ARRL Handbook 32-5.  Requires a fair amount 
of tuning to get going.

10 mW to 3 watt power amplifier.  1993 ARRL Handbook p. 32-18.  
DEM sells kits and parts.  The only critical traces on the 
circuit board are the input and output 50 ohm microstrips.  They
could be replaced with coax.

7 and 18 watt power amplifiers.  1993 ARRL Handbook p. 32-19.
Perhaps superseeded by hybrid modules such as the M57762. These 
are available from DEM amd RF Parts.

250 watt amplifier.  1993 ARRL Handbook p. 32-29.  2C39 tube 
operated in excess of rating, but is the most common way of 
generating lots of power on this band.  Lots of metal work 
needed.  Caution is needed, since this much power can easily be 
dangerous.

Power combining 250 watt amplifiers to get 400 watts.
April 1991 QST pp. 28-30

2304 MHz.

No-Tune Transverter Dec 1992 QST.  Artwork is available from the 
Technical Department secretary.
A 0.8 dB NF 14 dB gain preamplifier appears in the May 1989 QST, 
p 31-36 and the ARRL 1993 Handbook p. 32-22 to 32-28.  While 
no-tune, adjusting the bias current is sometimes necessary for
optimum performance with these preamps.

If a 14 or 15 volt supply is available, the Avantek UT0-2013
hybrid module in a TO-8 case will deliver 20 dBm.  This unit
is sometimes available in surplus assemblies.  The ATF-10135
may work as a power amplifier, except that device variations
(within specifications) as well as biasing/stabilizing circuit
limitations often limit the power below its 20 dBm power 
specification.

A repeatable no-tune 2304 power amp has yet to be published for
getting above the 20 mW level.  The adventurous may wish to take
nearly any power GaAs FET available, put it on a board with half 
wavelength 50 ohm traces, bias it according to the manufacturer's 
specification sheet (or whatever seems reasonable), and tune it
for maximum output power with copper foil.  A major difficulty is
that power GaAs FETs basically aren't designed for 2 GHz operation in
mind--perhaps indicating the lack of a big customer.  28 volt 
bipolar devices are available, except that amateurs don't seem to 
be interested enough to develop designs.

3456 MHz.

No-Tune Transverter June 1989 QST. Etching your own high accuracy 
teflon board isn't recommended, though the author will supply 
artwork.  Most people buy etched boards from DEM.

A 0.9 dB NF 23 dB gain preamplifier appears in the May 1989 QST, 
p 31-36 and the ARRL 1993 Handbook p. 32-22 to 32-28.  While 
no-tune, adjusting the bias current is sometimes necessary for
optimum performance with these preamps.

WA8NLC sells a pair of boards for using the AT-8140 and Avantek 
IMFET.  The AT8140 should put out a watt with 10 dB of gain.  The
IM2935-3 IMFET costs about $300+ new, but is one way to get 4 or 
5 watts on this band.

Much of the high power work is done with surplus TWTAs and solid 
state amplifiers.

5760 MHz
Simple transverter with no RF amplifiers.  A Single-Board 
Bilateral 5760 MHz Transverter," QST October 1990 pp 27-31.

Mixers, filters, and low level (4 mW??--data sheet says 5 mW
at 4 GHz) amplifier.  1992 Microwave Update. Mixers, etc. for 
5760 MHz, Paul Wade p. 71-79.

A 1.2 dB NF 18 dB gain preamplifier appears in the May 1989 QST, 
p 31-36 and the ARRL 1993 Handbook p. 32-22 to 32-28.  While 
no-tune, adjusting the bias current is sometimes necessary for
optimum performance with these preamps.

Much of the high power work is done with surplus 5 watt solid 
state amplifiers and TWTAs.

10 GHz
A transverter for duplication by experienced microwave 
experimenters has been written up for QST and is currently being 
edited.  It puts out 10 to 20 mW and has a noise figure under 3 
dB.

The Microwave Update 1991 and the Microwave Handbooks by the RSGB 
describes some kits sold by Petra, G3WDG's XYL.  The kits will run 
about $500 U.S.  The claimed noise figure is 3 dB and the saturated 
power output is +20 dBm.  There are many tuned stages to adjust 
for proper operation. (circa March 92)

Petra Suckling
314A Newton Road
RUSHDEN
Northants
NN10 0SY UK  Tel 8-01144-993-411446

NF 18 dB gain preamplifier appears in the May 1989 QST, 
p 31-36 and the ARRL 1993 Handbook p. 32-22 to 32-28.  While 
no-tune, adjusting the bias current is sometimes necessary for
optimum performance with these preamps.

A 0.8 dB NF 11 dB gain preamp appears in the Dec 1992 QEX.  A 
template is available for an sase from the Technical department 
secretary.

SHF Microwave Parts Company
7102 W. 500S.
La Porte IN  46350

She sells a wide variety of 10 and 24 GHz Gunn modules (new and 
used), as well as a small selection of parts and small horn antennas.

For the Really Ambitious:

5.7 and 10 GHz transverters that put out over 1 watt, 100 mW 24 
GHz transverter.  Noise figures are 2.4, 3.0, and 4.0 dB for the 
LNAs.  Parts availability could be a problem, as the author is 
Japanese.  Microwave Update 1992  5.7-GHz, 10-GHz, and 24-GHz 
All-Mode Linear Transverter 
p.100-146.

SSB/CW Equipment concepts for 24 and 47 GHz.  1989 Microwave 
Update.  How you might go about building equipment for these 
bands, assuming you can find the right pieces.  It took Tom two 
years before serious construction of the 47 GHz unit could begin, 
and he knew what he was doing.

24 GHz Low Noise Amplifiers. 1991 Microwave Update.  How to build 
amplifiers that take hours to tune up, even with experience and 
expertise.  10.8 dBm output for the best transmit amp, 3.5 dB NF 
for the best LNA.

Various Parts Sources
RF Parts MGF 1302, MGF 1402, and Hybrid Modules

Mainline Electronics 
P.O. Box 235 
Leichester LE2 9SH  England
has MGF1302, MMICs, and other semiconductors Dayton 92

Microwave Components of Michigan
P.O. Box 1697 
Taylor MI  48180  313-753-4581

Wide selection of parts, including MMICs, diodes,
and teflon board material.

DEM=Down East Microwave
Box 2310, RR1
Troy ME  04987   phone 207-948-3741   FAX 207-948-5157

MCM=Microwave Components of Michigan

M/A-Com Semiconductor Products Inc
Burlington MA  01803  Phone 617-272-3000
Probably not as helpful to amateurs as when the company was
owned by a well known amateur.

Advanced Receiver Research Box 1242
Burlington CT  06013 is a distributor for MA/-Com.
phone 203-582-9409.  They sell complete Gunnplexer transceivers 
with genuine FM for 10 and 24 GHz.

Jose Balzac 
14 St AB-5
Cero Gordo Valley
Bayamon, PR 00956

Where to Get the Pieces

     Here's a list of vendors that supply the parts used in 
the 10-GHz transverter.*** Catalogs and/or price lists are 
available from each listed supplier.

Down East Microwave, RR1 Box 2310, Troy, ME 04987, tel 
207-948-3741, fax 207-948-5157, and Steve Kostro, N2CEI, RFD 1 
Box 341A, Frenchtown, NJ 08825, tel 908-834-1304 (days) or 
908-996-3584: MMICs, MGF1302, chip capacitors, SMA connectors, 
mixer diodes (only DEM carries the HSMS 8202; both stock the 
HSMS 2822).

Mainline Electronics, PO Box 235, Leicester LE2 9SH, England: 
MGF1302, MMICs, transistors, voltage regulators.

Microwave Components of Michigan, PO Box 1697, Taylor, MI 
48180, evening tel 313-753-4581: MMICs, 15-mil 5880 board 
material, MGF1302, HSMS 2822, chip capacitors, UT-141, SMA 
connectors, feedthrough capacitors.

Nemal Electronics, 12240 NE 14 Ave, N Miami, FL 33161, tel 
305-893-3924: SMA connectors, semirigid cable.

Ocean State Electronics, PO Box 1458, Westerly, RI 02891, tel 
401-596-3080, fax 401-596-3590: LM555, 78L05, 2N3906, 2N2907A, 
ICL7660, 1/4-watt carbon-film resistors, electrolytic 
capacitors, tantalum capacitors.

SHF Microwave Parts Co, 7102 W 500 St, La Porte, IN 46350: 
HSMS 2822, MMICs. Also sells Gunn transceivers.

Small Parts, PO Box 4560, Miami Lakes, FL 33014, tel 305-557-
8222: brass sheet stock, stainless-steel screws, #2-56 taps, 
many other items of interest to microwave-equipment builders.

RF Parts, 1320 Grand Ave, San Marcos, CA 92069, tel 619-744-
0700, fax 619-744-1943: MGF1302.

***This is not intended to be a complete list of dealers that 
carry these products.
[end of sidebar 2]

North Tesas Microwave Society
c/o WA5TKU Wes Atchison
Rt. 4 Box 565
Sanger TX  76266  
 
NTMS Feedpoint comes out 6 times a year.  They sponsor the Microwave
Update, but it is a local club in many repects--monthly meetings and
tune-up sessions for getting the gear running.

