Re. Resonance

>Original Poster: Philip <shadow42-at-totcon-dot-com>
>I have recently been trying to determine resonance of my coil. I dont
>really know what value it has, but ive seen that quite a few people have
>measured theirs.  Does 243khz sound reasonable for a 4.5 x 20" coil?
>Thanks Philip Mac Duffie

You didn't say what you had for a top load.  My secondary is similar:

4.25"D x 23.25"L (winding length) 22 AWG wound on 1/16" wall dried/sealed
PVC drain pipe.  Many layers polyurethane.  Low voltage self-resonant
with no topload at 489 KHz.  With 4.5" x 15.5" toroid, Fr is 290 KHz.
With additional 6.25" x 24" toroid, Fr is about 205KHz.

Regards, Gary Lau
Waltham, MA USA