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Re: [TCML] Terry Filter Caps Suffering From Early Death


Be sure there are 10Meg resistors across them all and that none of those resistors has failed.

There value is pretty small and if there were and HV leakage, that might make the voltage across the string to be uneven and stress some more than others.

Tear one open and unravel it to see how the dielectrics look. Melted, one big blast hole, thousands of small holes usually along the edge of the metal.?

I don't remember of hearing of problems with those caps before.


Scott wrote:
Hello Everyone,

As I work on my second coil, it has come time to install the NST
protection.  One very odd problem I noticed with my last Tesla Coil, a
9/30, is that the caps on the Terry Filter would periodically blow out
for no apparent reason.  Even with a RF ground directly in the Earth
and no sings of arcing through the filter (with the exception of the
safety gap), the caps at the end of the strings would die for no

The filter is grounded with a single 10awg wire 1 foot long going into
a 2 foot long 6awg car battery cable going directly to my grounding
post.  It's positioned 2 feet away from the NST.  When a cap blows
out, it seems to have little effect on the coil performance, but as
soon as one goes, the ones behind it blow up very quickly.

Now the second coil is a 15/60, 3 times the power of first, and I
would like to get this issue resolved.  Does anyone have a possible
answer to why this is happening?  Is there a more robust alternative
to the caps recommended in the Terry Filter recipe:

Thanks for any help with this problem.  I'm sure the Filter has done a
great job protecting the coil, its just annoying replacing these
little 60 cent caps every 5 minutes of run time or so.
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