UHF FM Repeater

May 25, 2019 | Juan Rivera | HAM RADIO

This is one of the first Ham Radio UHF FM Repeaters in the Los Angeles Area. I built it in 1963. That’s right – 56 Years Ago! It was fashioned around a GE Pre-Progress line mobile radio. I cranked the output up from 7 watts to 50. I also built a touch-tone Autopatch when my area still used rotary dials. I had to decode the tones and convert the output to rotary dial pulses. My mobile was full-duplex. I built the diplexer from scratch.

It was all vacuum tubes except for the Touch-Tone decoder. It used TTL IC’s. That was a great learning experience!

Colinear Before and After

I designed a 4-element collinear array using copper pipe and a coaxial phasing harness. After moving to the Santa Rosa area in Northern California, and constructing KBBF-FM, I installed the repeater at the transmitter site on 4000-foot Mt. Saint Helena. The antenna was nar the top of my 75-foot tower. All was well (Left), until winter came (Right). This location had some of the worst icing conditions I’ve ever seen!

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