Is the "absolute" tuning of L5 relevant?
I mean, the output is based on the interference between two HF oscilators, so the absolute tuning frequency should not matter, but only the difference, right? Somewhere on the net I saw a text that said that you should tune L5 so that the oscillator produces 289-290 kHz at one point in the circuit (I don't remember where but I can look it up). In my case, the tuning frequency is probably something quite different, not 289-290 kHz, but I do get a reasonable signal output.
Does the "absolute" tuning of L5 have any effect on the linearity of the theremin? In my case, the highest two octaves are clearly "compressed", i.e. I need smaller movements there. Is this normal, or can I retune L5 and L6 to make all octaves approximately the same "size"?
Also, when I touch the antenna, I get 3 kHz output, but as soon as I remove the finger (even if it's still very close) the frequency jumps abruptly down by 1/2-1 octave. Is this also normal?