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Re: Getting to the limit with an NST powered SGTC

Original poster: "Dr. Resonance" <resonance@xxxxxxxxxx>

I'm being misunderstood here and I need to correct.

I advocate using 20-30 scrap wire turns to explore the entire possible
tuning range.  Some experimenters build a nice copper tubing 8 turn primary
only to discover the coil tunes at 11 turns.  They endure racing sparks and
all kinds of frustration before they realize they have too few turns on the

Always --- and I repeat ALWAYS --- start with a large number of "scrap 12
AWG wire" turns.  Start around turn 3 and move outward until you hit the
first resonance --- usually the very best point because it's the lowest
resonance point.  Use house wiring and just scrape a bare point every turn.

When you find this resonance point, example, at 7 turns, then wind your
final copper tubing primary at say 9 turns.  We usually go 2 over on most
coil designs.

Don't spend hours shaping copper tubing only to find out later you don't
have enough turns on the coil or have made the base too small or too large.

We use some old scrap pieces of plywood, 12 AWG scrap wire, and hold it in
place on cardboard edgeslit pieces and hot glue.  This allows us to find the
proper number of turns (first advantage) and, (second advantage) to only
construct the base as large as it needs to be.  A small coil on a huge base
makes the sparks look smaller.  A proper sized base gives a neat appearance
without having excessive (or too few) primary turns.

Your sec coil needs to be elevated approx 1.5 inches above the horizontal
plane of the primary coil and the racing sparks will stop --- assuming you
found the lowest resonance point (least number of turns) at tuning and are
not trying to run at some odd harmonic multiple.  In short, your sec-pri is
overcoupled and this will cause racing sparks.  also, elevated your sec the
1.5 inches will set the proper coupling and increase output slightly.

Dr. Resonance
> I notice that Dr. R. usually advocates tuning with a 20-30 turn primary
> tuning at much more turns than I currently am.  However I cant see how to
> do this without making the topload much larger.  And also I know that he
> would say allow at least an inch height between base of secondary and
> primary coils.  Are these the secret ingredients to squeezing the extra
> of performance I am not getting?  >
> Kind regards,
> Ian