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Reply to Jason Judd


From: 	Thomas McGahee[SMTP:tom_mcgahee-at-sigmais-dot-com]
Sent: 	Tuesday, September 16, 1997 8:21 AM
To: 	Tesla List
Subject: 	Reply to Jason Judd



> From: 	Jason Judd[SMTP:Jason.Judd-at-anu.edu.au]
> Sent: 	Monday, September 15, 1997 7:43 PM
> To: 	Tesla List
> Subject: 	Re: Peak cap voltage, was 12kV, 30ma TC specs, 42" spark
> 
> 
> Hi all,
> 
> I am just starting to get good results with my 6" 15Kv 60MA setup.
The tank
> capacitor is 14 nF (for 50Hz) rolled poly (two series 28 nF caps).
The best
> I have done so far is 35". I am using a tripple gap system quenched
with a
> microwave oven fan. What I have found is that to get the long
sparks the
> gap must be made quite wide to take advantage of the resonant
charging.
> When I got to about 12MM (1/2") the terminals from my two 15Kv 30
MA
> tranies started to arc to the case which is about 10MM from the
edge of the
> HV insulator. I suppose this is a good saftey gap and may well have
saved my
> transformers.

Try using more gaps and keeping the size of the individual gaps
smaller. 
Three gaps is really not enough. The fan you are using will only
provide 
a minimum of cooling. I highly recommend the use of a vacuum gap
system.
This is not all that much harder to build. Contact me if you need
more
details about such a system.

You are having to pull your gap wide to get max sparks, and that is
not
good. Try increasing the size of your capacitor. That will require
some 
re-tuning, but will allow you to process more power with a smaller
gap 
setting. The TESLAC program recommends .0075 mfd at about 38KV.

With this arrangement you would be getting more gap firings per
second
and thus the total energy processed will be greater, even though you
would typically have a lower max gap voltage. Your gap must be quite
robust, though. I recommend eight or more gaps, 3/4 or larger hard
copper pipe, at least 3 to 4 inches long mounted flat with a really
good vacuum motor sucking air right through the gaps.

PUT A TRUE SAFETY GAP IN YOUR SYSTEM. It is only sheer good luck that

you didn't destroy your transformer when the sparks raced across your

HV bushings!!! It would be a SHAME to destroy a 15KV 60 ma tranny
just
because you had no safety gap!

> 
> My question is how far should I open the gap to take advantage of
resonant
> charging ? 

With a 15KV neon using resonant charging may be overkill.
Don't destroy your transformer!

> The gap has never miss fired yet. It appears to me that I should
> set the gap to fire around the 30 KV mark. I'm not game to do this
because
> my caps were not designed with this voltage in mind , but in the
future
> they will be.
> 

Jason, your transformer wasn't designed for that level of voltage
either.
You will do far better to increase your cap size and build a gap
that will help you process the power at a lower voltage level.
You want to get the max spark possible without destroying your
cap and transformer.

> Cheers,
> 
> Jason
> 
> 

Hope this helps.
Fr. Tom McGahee