Keppinger tube theremin builders - Finding Parts

Posted: 9/20/2010 1:29:11 PM

From: Richmond Hill, Georgia

Joined: 9/18/2005

The variable cap value is not critical. Just be sure to have the minimal amount specified. A little more is okay; you will just have more C per revolution, and your tweaking/tuning will be a tad more touchy.

Modifications are okay! I had to mod mine just to get it to work reliably.

Posted: 12/16/2023 10:12:13 PM

From: Anacortes, Washington

Joined: 5/5/2009

Hello; Ross here. I have some questions and a few requests.
I have what I remember is a Mark Keppinger Tube theremin (chassis') that uses theĀ 
6sn7s, 6J5, 6H6, 5Y3, 0D3, and 6V6 tubes.
The tone sound is as close to Clara as I will get at the moment- it's acceptable.
[Am also playing with building an RCA that I use to play that the Bellingham Sparks Radio Museum under John Winters.]
BUT my "Keppinger?" chassis linearity is horrible. Low octaves are nice but can get too extended. The high pitch octaves are impossible to play the closer you get to the pitch antenna.
Does anyone have the SCHEMATICS to this chassis?
Does anyone know tube circuitry enough to supply a additional circuit or repair to extend the octaves and space the linearity out more evenly?
I like to play Classical pieces and am struggling to play this thing.
I would appreciate any help you all can give, short of a free shovel and grave plot. :o(
We know enough here to modify the chassis but are not circuit designers.
Any "DRAWN schematics" can be interpreted- I DO NOT know how to read "verbal" vacuum tube circuit technical language.
I can easily READ any visual schematics.
Please if anyone can help send some PDF schematics?

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