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Blown Neon transformers

 * Original msg to: Jwatson-at-students.uwf.edu

Quoting Jim Watson <jwatson-at-students.uwf.edu>:

> When I was tuning this coil, the only sparks that I got were 
> some very intense thick blue arcs that went from one point on 
> the toroid to either the beginning of the primary (about 3') or
> the beginning of the RF gorund.  The arcs were very fast, went
> straight down, and I could not tell precisely where they were 
> striking.  The point that the arcs originated from was the 
> blunt end of a brass screw that was pointing down (it is now 
> very smooth and is pointing up).

This indicates a possible coupling problem. 1/4 wave coils, when
coupled too tight, splash sparks up and down the secondary. Raise
the secondary up a bit to loosen the coupling.

> I would appreciate any comments or suggestions that you can 
> find the  time to make.  I would like to think that the 
> transformers were weak, but I just don't really believe they 
> were.  I don't want to replace them and have the same thing 
> happen again.

Jim, neons are inherently weak. They only serve well on smaller
coils, and/or when they are treated like babies.

This coil you just described is ready for a heavier commercial
type transformer with external ballast, either a potential or
pole pig, possibly a pair of plate transformers in series. You
already have a very sturdy cap in the .025uF-at-20kvac CP unit.

If you can pick up some used neons cheap then go ahead and put
them on-line, sans rotary gap, until you can get commercial
transformer for your power supply.

A am sorry about the failures happening so quick, but this is a
very powerful coil set you are energizing. It is sure to blow
through the weak spots, which in this case was the power supply.
When setting up and energizing a larger system for the first time
I like to use some 9KV neons and a static gap to get things in
rough tune, especially if I do not have access to an O'Scope,
signal generator, and frequency counter. 

After everything checks out with 9KV neons and a static gap, then
I switch over to a commercial transformer (well ballasted) and a
rotary gap running at 3k+rpm.

Try it, you'll like it.

Richard Quick


... If all else fails... Throw another megavolt across it!
___ Blue Wave/QWK v2.12