RCA Test Oscillator, ca. 1929

[polyphase]

Here is a piece I picked up on the auction site a while back, thinking it might be a fun restoration project. That was not to be. All it needed was batteries.

It is an RCA Test Oscillator, model TMV-97-C, circa 1929. Range is 90 to 25,000 kHz with built in modulator. It is spot on accurate, but the numbers on the vernier are near microscopic, so a magnifier is needed (at least I need one).

[bob91343]

It's a beauty; I would love to have just the vernier dial. What circuit does it use? I see an 80 tube, which would be a rectifier, yet you are running it on batteries.

[mstaton]

looks like 2 80's??

[bob91343]

I never saw an 80 used as an oscillator. I suspect something like a 45. But what is the modulator?

[mstaton]

I doubt it's 2 80's but the lettering is worn down to where you cant tell in the pics

[bandersen]

Cool oscillator. I believe the tube on the right is a 30. The other other might be a 30 too.

[snelson903]

I aways like old test equitment ,look nice and in good shape. its def. a 30 i have a army version of that one from 1945 and it has at least two 30 's in it

[bob91343]

Two 30 tubes would do it, one the rf oscillator and one the audio oscillator. So it does need batteries.

[polyphase]

Originally Posted by bob91343

Two 30 tubes would do it, one the rf oscillator and one the audio oscillator. So it does need batteries.

I haven't been able to find the official schematic, but you are exactly right.