My coil spacing (in mm) is currently |3|3|3|6|, which I think may be too wide. So, I'm going to drop this down to |2|2|2|3 or 4|. Also, I'm using acrylic spacers too keep things nice and uniform for the long-term. O-rings would eventually dry out and crack, risking contact between coils.
And as far as what effective freq to set it at, it looks like I'm just going to have to step thru the range. It's gonna take time. Would be nice to know exactly what harmonic areas to target, tho...
55. Fibonacci number. Interesting. I'll be keying on those, for sure...
I presume you are keeping each coil linked together?