Re: Blown Neon transformers

Subject:       Blown Neon transformers

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

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

>> I completed my large transformer today, and two of the four 
>> neon transformers went bad after just a few minutes of 
>> operation.  I was using four 15kV neon transformers in 
>> parallel... The spark gap consists of two cylinder gaps in
>> series with a rotary gap. 

>If you are running a rotary gap on a coil powered by neon sign
>transformer you are simply begging the neon to fail.

>I don't know how many times I have posted about this:

>Neons or other shunt core transformer don't need rotary spark
>gaps. By placing a rotary gap on a coil powered with these
>transformers you are asking for trouble in the form of a failure.
>These transformers actually deliver better performance with high
>quality static gaps.

>Save the rotary for a pole pig, potential, or plate type power
>supply the requires external current limiting.

>Richard Quick

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

Jim Watson,

I don't know how cheap or plentiful neon xfmers are in your area but 
here in Ontario, Canada, the neon sign guys like to hang on to good 
used transformers for their high resale value in case a customer needs 
one.  With a new 60MA 15KV neon priced at about $175.00 U.S., before 
tax, a customer at a pizza parlor with a sign out will gladly fork over half 
that to obtain a good used transformer.  I have been able to buy a good 
used pole pig like a 10KVA, 16000 volt unit from a utility company
for less than the price of a new neon!  With your new .025 cap and rotary break 
it looks like a good time to invest in a 5 KVA pole pig.  Good luck 
with your coil!  Sounds like your'e getting there.  If it makes you 
feel a teensee, weensee bit better, I just blew up two furnace 
ignition transformers in the continuing quest to come up with 
protection.  My new handwound RF chokes (air core 142mH) appear to work
OK by themselves, and I still haven't lost a transformer with them,  but when you add
a 250pF bypass cap to the transformer output terminals, KA-BOOO....phttt!

Happy coiling! rwstephens