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Re: multiple gap question


to: Ralph

In my parallel copper plate subdivided sparkgap design I use a spacing of
.010 inch and this is achieved by machining strips of G-10 phenolic to .010
inch with a tolerance of .0005 inch.  A good machine shop can do this for
you.  We use 2 1/2 x 2 1/2 inch square strips of 0.125 (1/8th) inch copper
plates with two "spacer" strips of G-10 which run 2 1/4 inches deep into
each stack.  We leave the back 1/4 inch as the blower fan tends to blow all
the sparks to the rear and in this area where most sparks occur there is no
spacer material to melt.  With the heat dissipation in the copper this
really isn't a problem anyway -- just a precaution.

A very gentle clamp is formed with two 4 x 4 inch square pieces of 1/4 inch
thick G-10 plate.  1/4-20 phenolic rods vertical in each corner held with
fibrenuts.  Hand tight plus only 1/4 turn on wrench to tighten.  Small
amount of GE Silicone II applied to each strip adheres it to the copper
plate for added stability during rough transport, etc.

I'm drawing up a print set for publication in a future issue of TCBA
Newsletter.

Regards,

Dr. Resonance

-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Saturday, February 12, 2000 12:45 AM
Subject: Re: multiple gap question


>Original Poster: Parpp807-at-aol-dot-com
>
>In a message dated 2/11/00 2:33:18 AM Central Standard Time,
tesla-at-pupman-dot-com
>writes:
>
><<  Mine were gapped at about 0.03", I used a feeler gauge to verify that
> all segments were parallel to one another.  Are yours reasonably parallel?
>>
>
>Hi Gary,
>What's "reasonably parallel?" That's part of my problem and I am wondering
if
>anyone has developed a particular technique for spacing the couplings? I
have
>mine mounted on 8-32 screws and fixed with nuts so I can adjust the
vertical
>height. They look like the olive on the end of a toothpick. :-))
>The toothpicks...uh screws pass thru 1/4-inch thick acrylic with a slot cut
>into it so the screws can slide horizontally. So I have horizontal and
>vertical freedom of travel and adjustment. A nut and washer on top of the
>plastic and under the coupling
>enable the whole toothpick to be locked in place. Brilliant, huh? The big
>flaw is that as soon as you tighten down on the lock nuts it changes the
gap
>settings. Lucky if I can
>guesstimate within +/- 5/1000ths. I cut up a Tropicana OJ jug for shims to
>help get a little more uniformity. Any suggestions---please? The sparks are
>all off of the circular face.
>None are seen to come from the cylinder walls. I have been able to set the
>gap at
>0.028 - 0.030. The mmc is at 0.011 uF. Not even a gap of 0.018-0.020 will
>fill a 0.022 uF mmc.
>
>Happy day,
>Ralph Zekelman
>
>
>