I've been fiddling with my Mk1 Jaycar theremin lately, I've applied Maxie's mods, built a different cabinet and tuned it. Pitch-wise it's reasonably playable, but the volume circuit's giving me trouble.
The transition from quiet to soft is quite abrupt and in the transition zone, there's a "put-put-put" sound. I replaced the 2k-ohm trimpot with a 25-turn version and this helped a bit, but I'm still getting the noise.
I'm using the original pitch antenna that came with the kit, I replaced the volume plate with an 8cm diameter circular antenna I pirated from a TV antenna, but it's probably still a bit small.
Any help would be most appreciated :)