Four Band SSB Transmitter
Front panel. The case is made from some scrap tempered aircraft aluminum I got from the sheet metal shop at the Air Force base where I was stationed at the time. In retrospect this radio was an ambitious undertaking, but at the time I was in my early 20s and it never occurred to me that I might not succeed!
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I built this transmitter from about 1968 to 1972. It was originally a phasing type rig that I later converted to a filter type when I could afford a filter. The design is basically one I found in the ARRL SSB handbook titled "Filter Type with 100 Watt Output". Among other things, it uses a 7360 tube for the carrier oscillator and balanced modulator, a circuit I had nothing but trouble with.
This radio was described in the September 1992 issue of Electric Radio.
When it was built the only test equipment I had was a Heathkit VTVM and an RF probe! Needless to say when I finally got some decent test equipment two decades later I discovered it needs a lot of rework. The chassis is way too small, making modifications difficult in my "later years". Maybe one of these days I'll tear into it...
Top view. A single 6146 PA puts out about 50 watts PEP on 80 thru 20 and hardly anything on 15 for reasons I have never figured out. The filter is a 9 MHz crystal unit with 2.8 KHz bandwidth. It was made by an outfit called ESEL (Excelsior Springs Electronic Labs). Bet you never heard of them.
Bottom view. A lesson learned here is don't homebrew with a chassis that's too small! Familiar ARC-5 VFO components are seen in the upper right. I have used these in all my radios with excellent results.