Homebrew all-mode HF transmitter with a pair of 6KD6 sweep tube finals (above) from 1974.
I've been using a 1950's vintage Collins KWS-1 as my daily transmitter for almost 20yrs now. It likes to drift a few hundred hz over 2 or 3 hours. This was state of the art in 1956 but nowadays people get very concerned when they hear someone drift that much. Therefore I decided to upgrade its frequency stability to be at least equal to modern rigs. I designed a homebrew DDS frequency control board for the KWS-1 using an AD9851 chip with OCXO reference.
Also added an AFC stabilizer to the VFO tied to the same OCXO reference. The KWS-1 still works just like before and the modifications are completely transparent but the OCXO now makes the 1956 transmitter extremely stable at 0.1ppm.
1774634 Last modified: 2015-03-11 16:40:45, 1197 bytes
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