[sdiy] Shielding around Theremin RF Oscillators

[R. D. Davis]

Looking into mods for my Theremax, I happened upon Fred Nachbaur's
great website.  Unfortunately, Fred Nachbaur is deceased so there's
not much point in emailing him to ask him about his Theremax mods, and
not being skilled at using a Ouiji board to contact him, well, that's
that.  So... I'll ask here.

At http://www.dogstar.dantimax.dk/theremin/mytherem.htm, there's a
photo of his super-modded Theremax, and it shows what looks like
copper shieldling around the circuitry for each RF oscillator.  Does
anyone know if that's copper, or, if not, what's best to use?  Is the
shielding likely connected to ground?

Another web site I happened upon recommended swapping out the PAIA
supplied IF transformers for Xicon IF transformers since they're
better for tuning (more turns, I think)... so I'm ordering some of
those.  Has anyone else here swapped those? 

Also, I see he's added an echo board to his theremin.  Just the other
day, I happened to find an old assembled Radio Shack reverb kit under
some other things, along with the original documentation, that didn't
work right about 25 years or so ago, which I never got round to
fiddling around any more with.... if I can find some mu-metal to
shield the AC transformer on its pcb, or better yet the entire PCB,
and if I get it working again, I could put that in the theremax case,
and perhaps get power for the theremax from that as well.  If I recall
correctly, it uses an SAD1024 delay-line chip (still there).

-- 
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