HI:
It's perfectly normal for the pitch antenna to squeal when touched. Surprisingly, you can get very interesting effects doing just that.
(If a volume antenna squeals when touched - big problem.)
However, your issues of severely impaired range of octaves CAN be dealt with. It would be helpful to know a few things:
First, are you saying that once the change occurred, that your range shrank even AFTER you'd left the school -- in other words, the anomaly became permanent?
Secondly, if you are setting your pitch knob at 5 o'clock to get "zero beat", that's what I'd consider to be too far over. Is that the case -- that 5o'clock is where you achieve zero beat?
Third, has anything like this happened before?
Fourth, did ANYTHING, regardless of how inconsequential, happen to the theremin during transport? Was it unprotected (i.e., not in a carrying case), did it get jostled, knocked during setup, etc.
The most likely fix would involve re-tuning your pitch circuit – I’ve done this approximately three times to my theremin in the past eight years. It will give you back a wide pitch range again. In addition, you can also recalibrate ( perhaps not the correct term, but Kevin K. really knows his stuff and he can definitely help with precisely what to call things ) the pitch knob. In either case, you will be making very “fine tune” adjustments to the little “screws” on the tops of both the fixed and variable frequency oscillators. (How’m I doing, Kevin? ) It’s weird – I can DO it, I just have trouble SAYING it.
Both of these procedures involves opening up your theremin to make adjustments with a little plastic tool that’s like screwdriver. Exactly what to do depends upon what theremin you have. For a standard Etherwave, it can take about forty-five minutes. Increasing the pitch range is fairly straightforward. The trickiest part is getting the pitch knob to give you zero beat when positioned at about 12:00 rather than 5:00. It’s tricky because the lid has to be taken on and off repeatedly to make the adjustment.
If you’ve got a standard Etherwave, there are instructions in the manual, but they were written by Moogian Martians, so they’re a little difficult to understand.
Anyone who wants to jump in here, if you’ve performed the procedure and can offer a concise written description of how to do it?