Original poster: "Dr. Resonance" <resonance@xxxxxxxxxx>
You can always see a single prominent fundamental freq usually at or
close to the 1/4 lamda freq. We use 0.96C when calculating this
freq as the propagation never quite approaches C (speed of light).
When you couple two coils with a nice toroid at least 2 X sec dia.
you can see on a scope the fundamental freq. If you increase
coupling too much this fundamental will split into two side
frequencies each of which starts absorbing energy and creating beat
frequencies.
You could be right regarding the interharmonic distortion. I have
not investigated this in detail, but we always check our coeff. of
coupling right to the peak where it starts to split and then reduce
it a bit in our initial design work.
I guess the very best source to help make this clear is the Radio
Amateur's Handbook --- they have good drawings in there illustrating my point.
Don't overcouple and racing sparks are simply a non-issue.
Dr. Resonance