2023-11-27 RCA BFO Audio Oscillator Photos

Chuck commented about the audio oscillator being a BFO, and it reminded me that I’ve got an old RCA BFO audio oscillator stuck away in the garage. It was a cheap way of getting an audio sine wave that covered the full audio band without any switching. Nowadays it’s all done in sine and other waveforms by a function generator, up to 2 MHz or more.

So I dragged the old clunker out and took some photos. Sadly, when I got it the power transformer was melted and dripping tar. So it’s never worked for me. And it was missing its tubes – no worry, they’re marked on the chassis. This is probably the first and last time you’ll ever see one of these. Almost all the tech benches had a HP 200 audio generator, so why bother with cheap RCA equipment? 👍

The front face and dial would look impressive if it was cleaned up. But I’ll let someone else do that. I’ve got a half dozen function generators that need to be fixed. When was the last time you saw one of those chassis mounted power resistors with multiple taps on it? I don’t have a schematic but I would guess that the taps are for screen grids? Or just lower voltage B+?

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