Re. Great sparks! Then....

>Original Poster: Travis Tabbal <bigboss-at-xmission-dot-com> 
>One question, durring my higher powered runs I noticed something I had not
>seen before. I kept getting a small arc from my secondary ground wire to
>the inner turn of the primary. This happened at the higher power levels. I
>tried putting some poly in the way, but that didn't help.
>Do I need a larger inner turn on the primary? Or am I missing something
>here? I'm a few turns in from the outside on the tap, so I could loose a
>turn or two from the center and retune still. It's a 6" secondary with a
>flat spiral primary, inner diamater on the primary is 8". 

Do you have air core chokes?

I once had a problem were any part of my tank circuit wanted to arc to
ground.  The problem was my use of large air-core chokes (~8mH, 2"Dx7"L)
in a classic LCR low-pass filter NST protection circuit, between the main
gap and the NST terminals.  Despite my using 3K ohm de-Qing resistors,
the chokes insisted upon ringing, elevating my entire tank circuit to
some incredible potential above ground.  Changing to heavily insulated
ferrite-core chokes eliminated the problem, though I now believe that
chokes do more harm than good.

Regards, Gary Lau
Waltham, MA USA