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An old picture of my homebrew all-mode HF transmitter with a pair of 6KD6 sweep tube finals (above) from 1974 when I used to operate as DU1AFS.

Today I like using a 1950's vintage Collins KWS-1 transmitter. 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 upgraded its frequency stability using an AD9851 chip with OCXO (oven) reference.

Also added an AFC stabilizer to the KWS-1 VFO tied to the same OCXO reference. The KWS-1 still works just like before and the modifications are completely transparent. There are no extra switches and no digital display. The OCXO makes the 1956 transmitter extremely stable at 0.1ppm. The VFO is now truly set and forget.

AFC control unit as installed on top of KWS-1 vfo (above).

KWS-1 power supply with access door open.

Popular washing powder since the late 1800's until the mid-1950's, the origin of the name for the Collins KWS-1 and 75A4 twins. Fairbanks called the black twins Goldie and Dusty during their advertising campaign. Goldie and Dusty were real people who toured the country advertising the product. By late 50's P&G entered the business, introduced modern marketing methods, clobbered the competition, and Fairbanks famous product dissappeared!

Homebrew remote antenna tuner in weather proof container located outdoors. It is remotely controlled from inside the ham shack.


8179069 Last modified: 2017-06-25 01:04:53, 2316 bytes

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