Re: terry filter oh no!

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>

Hi Josh,

At 04:08 AM 6/29/2003 +0000, you wrote:
>I guess its time for a new "terry filter"
>Specs of tonight's run:
>3.5/24 inch coil 24awg
>flat pri 16 turns, it likes between 5 and 8 turns depending on top load.
>120bps srsg
>34.6nf mmc geek
>15/60 nst
>classic "terry filter"

Sync gap coil with a big primary capacitance (LTR++)...  Should have been 
just fine...  Maybe the big cap caused the NST to saturate the shunts 
allowing far more...


>I was using a small top tonight. 3" duckt about 12" diameter.
>Set safety
>Found tune at 6 turns
>Began rotating the gap motor to adjust phase. At some point the gap fired 
>intermittently, like it was missing a fire. As I moved it back, I saw that 
>the plastic housing on the filters caps were all cracked and coming off 
>exposing the inside.

The filter caps should never blow!!!  That is a new one there!!!  Cooking 
the MOVs is normally the only real failure mode.

>Darn it I blew the caps!
>The mov's didn't show any thing out of the ordinary and everything was 
>cool, like at the start. That is except the power resisters they were worm 
>like always. It's a shame! And so close to the 4th!
>         Terry, I'm sure this filter saved a few of my nst's. But I fried 
> the filter twice now. (most likely due to miss use, poor construction or both)
>Can you recommend more robust components for your fine filter?

Can I "borrow" your "terry filter"?  I would like to check this one 
out.  I'll pay shipping here and back.  Probably also fix it if I got the 
parts on hand ;-))  I would like to take a direct look at all this to find 
the trouble.  I have recently added to the number of recommended MOVs, but 
filter cap failure is a definite "new" problem.  You "could" run with 
"just" well set safety gaps if you need to run on the fourth...

Those filters are usually very trouble free.  Hopefully, we can find the 
problem and get your's all fixed ;-))

Cheers,

         Terry


>Thank you
>Read you later
>Josh