RQ Spark gap numbers

To: tesla-at-pupman-dot-com
Subject: RQ Spark gap numbers
From: Phil Chalk <phil-at-eagles-dot-com.au> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Mon, 10 May 1999 16:41:45 -0600
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

Hi all,

I'm ready to build a (an ?) RQ spark gap, all the copper's cut, bolts
in, etc.  I 'knocked it up' quickly with 7 pipes (6 gaps) just to see
how it went.  Seems fine so far.

I'm using 25mm (1") tubes, 80mm (3.15") long, inside a 150mm (6") id pvc
pipe.  In one end is a 150mm  230cfm (!) fan, the other a nice pvc
mounting flange.  I'll be able to comfortably fit 13 tubes maximum,
giving a total of 12 gaps.

The gap will (soon) be used on a coil with 6.5" x say 25" or so
secondary, & initially at least, powered by a 15kV 60mA Neon.  I'll
never likely go over 15kV, but will probably increase the current at
some time.

Two questions, then:  I know many of you have considerable experience
with these things.

1) What do you suggest as a TOTAL spark-gap length for the 12 gaps, for
15kV/60mA/6"  ?

2) Would I be better using it as (up to)12 (small) gaps in series, or as
two series strings of six, in parallel  ?

I know the answer for 2 (in fact both) is 'trial & error' , but I'd like
to draw on the collective experience here before I go any further, as it
affects slightly how/where I drill the holes & then how to gap it.


Thanks for all opinions,

PhilC.