electromechanical multi tone generators for tune up or test.

[Opcom]

Just thought I'd throw this out there remembering the dirty 150Hz B+ filtering of the old Moscow radio.

This piece of gear MD-83A/ARN is possibly from an airfield, making the 90Hz and 150Hz tones for glide path (?) as well as frequency-modulating some higher tones of about 9KC at 30Hz. It also makes 1000Hz.  Beside a frivolous suggestion of use as a Voice of Moscow impersonator, this looks like a good, if monstrous, test tone generator.

All the tones are available and can be mixed externally. 2-tone, or as many as 5.
2-tone signals keep the average power down in an amplifier during tune-up while allowing peak power to be seen on the scope etc.

The really cool thing about this item is the tones are all created by either toothed wheels or little synchronous motor-generator sets. It's a pretty rare thing, all mechanical.  Turned up in a load of 7 oscilloscopes, among other oddities. When it rains it pours.