Retrofitting old tube radio into Theremin: can it be done?

Posted: 3/9/2019 4:30:14 AM

Joined: 3/9/2019


I have an old tube radio from the 1930s (ish). It receives three bands: AM, and two others that have no broadcast anymore, probably lower-frequency on the FM scale and something else. 

This afternoon I began wondering if I could make this radio into a theremin. It has a handsome wooden case, and I can envision it with a rod out the top and a loop out the side. 
I have no experience with this kind of engineering but am keen to learn and experiment (hopefully not to the ruination of my old radio). 

What does everyone think ?

Posted: 3/9/2019 5:56:15 PM

From: 60 Miles North of San Diego, CA

Joined: 10/1/2014

I have confidence that if you are young enough when you start your project... you will reach your goal.

If at anytime along the way you think it was not the best approach, I will also support that decision.


Posted: 3/11/2019 5:23:39 PM

Joined: 11/13/2018

It's probably do-able because it's been done (more or less). It will lead to the "ruination" of your old radio though - it won't be a radio when you're done with it. In terms of restoration and value as an antique a radio converted into a theremin will be worth less than one carefully restored to factory specs.

The major challenges IMHO will be fitting the coils (if you go with a design that requires large air coils) and keeping the speaker in place.
You can probably get away with removing the speaker if you change the design to feed an external power amplifier but a tabletop type radio will still not have the room for big air-core antenna inductors so you'd need to look into design alternatives there (big plate antennas & low tank capacitance so you don't need inductors, pi-wound inductors to save space, etc.)

Posted: 3/12/2019 12:03:42 PM

From: Canada

Joined: 8/1/2008

I have seen a couple of very cool looking theremins that were housed in vintage radio cabinets, but their insides were standard Etherwaves that had been transplanted. 

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