The Microwave Project
Page 2

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Microwave pg. 1
Microwave pg. 3
Microwave pg. 4

Other Sites

Mt. Lemmon
Mount Bigelow
Mule Mountain
Heliograph Peak
Elephant Head
Dark Canyon

The next big breakthrough occured in 1996 when K7PRS came across a pair of Granger-Telettra HR-2 tranceivers. These were much more modern synthesized 2GHz tranceivers. We were able to obtain a service manual and set out learning about the radios. It seems that they were designed to work in frequency bands located either above or below the amateur 2GHz allocation. Upon further examination we found that the micro-stripline circuit boards were identical for either tuning range. The manufacturer simply tuned the striplines with some silver paint. Now all we had to do was learn to tune micro-striplines!

Close up of Telettra RF section
We were in luck, however, because our group has expertise in the form of Jim, WA7CJO, a microwave moonbounce expert. We took the problem to him and after tuning a number of the radios he taught us the procedure to get them moved to the right frequency range. We also learned a lot about MEK and silver pen solvents.

All we needed now were more radios. It was time to make a trip to the Dayton Hamvention.

In 1997 a large contingent of CARBA and SARBA members made the trip to Ohio to find more radio equipment. We searched the flea market with great diligence until on the last day Chris, N7TWW, made the find of the weekend. There were about 25 of the Telettra radios sitting on the bottom shelves of a surplus dealer's display. Negotations were made, money was pooled together, and the radios were loaded into John, KC7IM's motorhome for the trip to Arizona.

RF Filter
Microwave filters and circulator

Once we recovered from the trip, it was time to begin making things work. First we tuned up 5 pairs of radios, but we couldn't use them without filters and duplexers. The filters were a big problem. We needed filters and circulators to make the radios full duplex into one antenna. We had to start disassembling the older SS-2000 radios we had. We found there were two types of filters and the ones that were most plentiful required machining to make them tune in the ham band. KB7RFI came to the rescue and prepared all the filters we would need for our original project. This involved shortening the tuning elements, mounting them on rack panels with the circulators and cabling up the panels to make duplexers.

Meanwhile, N7CK and WA7ELN tuned the filters and antenna feeds. We also had a MUX party where we checked out, repaired and aligned about 40 of our mux cards. MUX tuning party at WA7ELN's

The microwave construction story continues on Page 3

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