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This week is the week...need help on spark-gap spacing



Subject:  This week is the week...need help on spark-gap spacing
  Date:   Wed, 28 May 1997 11:15:27 -0500
  From:   Shawn Collins <rubidium-at-worldnet.att-dot-net>
    To:  tesla-at-pupman-dot-com


I am finally at the end of a three month endeavour and need help on
setting
my spark gaps.

I have a 15KV 60mA neon, 15 turn 3/8" tubing primary with .0105 uF flat
plate cap (freezer bags and aluminum foil), 1050 turn 6 " secondary (#22
AWG) and 24"x4" torroid. I am using a single forced-air gap.

I have checked the resonant frequencies of my primary circuit with
scope,
sine generator and freq counter set up and have an incredibly high-Q
primary. (deviating 5% from center frequency I almost lose the signal).
I
have made some 180uH protection chokes for the neon and have protection
spark gaps made on the neon side. 

Would someone please help me with a startup procedure for this? I intend
to
mount the secondary tonight and find its resonant frequency and then
match
the primary to it before any startup.  

 I would assume I  should start with the protection gaps pretty wide
open
and a fairly narrow main spark gap and a low variac voltage. I then
intend
to slowly increase everthing until I am running at 110Vac on the variac.
What should I expect for approximate final gaps for the main spark gap
and
the protection gaps (just ball-park).

 Also, how can I best tune this ? I have heard of holding a discharge
ball
near the torroid and tuning, at low power, for maximum discharge length.
I
am concerned about over/under coupling (my conical primary (30 degree
rise)
is 8.5" diameter on its center with an insulating plastic between it and
the
secondar). THe base of the secondary winding is about even with the base
of
the primary.

Thanks alot for your help.
Shawn