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.