My Collins KWM-2

by Ernst F. Schroeder DJ7HS

View of my KWM-2 with companion 312B-5

When I first got my amateur radio license in 1961 it was still AM time. So I built my first transmitter around a Geloso VFO and used a RL12P35 as PA with Geloso pi-network. AM modulation was done by an EL84 via the screen grid.

My elmer and good friend Waldemar, DJ6DK (sk), who taught me how to wind transformers, had started to work on SSB. From somewhere he had obtained a circuit diagram of a real SSB transceiver, a KWM-2 from Collins. So we sat down and analyzed those circuits item by item, until we had memorized that whole diagram and all its functions.

Waldemar then successfully built and used more than one single-band version for 80m with just a single 6146 as PA. This was well before the Heathkit mono-banders became available. I also tried my hands at an 80m SSB transceiver, but before I could really finish it other things became more important.

Therefore I got my first Collins device, namely this KWM-2, not before early 1991.

After I had it restored to good working order I started to look around for bits and pieces that could be added, improved and built, always in order to keep up the operational quality of that Collins transceiver.

Here are separate descriptions of some of the things I did:


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