Today's topic is a Conversion of the Hallicrafters FPM-300, a 1970's Hybrid Transceiver into an all solid state QRP Transceiver. The Original FP M-300 Long story short about 7 years ago (maybe 9 years) I bought a deal on eBay -- a Hallicrafters FPM-300. That deal turned into a nightmare! The Original FPM-300 was marginal -- the unit I bought was beyond fixing. It drifted, it oscillated, and the rubber band switch assembly kept getting out of sync. [There was a rubber band toothed drive belt that when you engaged the band switch controlled several switches.] Think of the crappy dial string mechanism on the S-38E. In desperation I pulled the solid-state main board and S Meter and sold everything else -- net loss was $20. Not willing to let well enough alone, I designed a QRP Rig around the Main Board and S Meter. This is what we are showcasing today. Yes, this is an older project, but I thought in light of the Matchbox Transceiver episode on the recent hackaday this is right in
Could a Hackaday Lurker pull this off? I have always had penchant for Ten Tec Radios and when I spotted a Ten Tec Model 150A commercial radio an idea came to mind. Why couldn't this 8 Channel, 2-12 MHz SSB/CW transceiver be modified for the lower ham bands? I found one on eBay and the cost was $99. Heck if it was a bust the parts alone would be worth $99. This is not a project where you can simply heat up the iron and solder a few parts and you are there. It is a project where you need the manual, and you need to understand how the radio was designed and intended to work. The stock 150A covered 2-12MHz with a 12MHz IF and operated USB. The BFO/Carrier Oscillator was at a fixed frequency and to add LSB requires a second filter. Drake (and others) did this in the TR-3/TR-4. I could not find the LSB filter so with a bit of Arduino/Si5351 magic I was able to use a single filter. I ran across a ham who worked at Kachina and he had a set of 16MHz USB/LSB filters which he suggested usin