Hello all,
I've been struggling to build a lowpass ("Terry") filter to protect my NST
from RF feedback. The first one suffered arc-overs because
the capacitor leads were too close together, and the second one had the
capacitors fail - apparently only 9kV per rail wasn't enough. It's a 12kV
NST so I assumed 18kV > 12kVx(sqrt 2) and therefore would be sufficient.
Apparently not.
What suggestions are available for those who have made a NST filter that
was successful? Particular capacitor types/brands would be welcome, as well
as how the physical layout was accomplished. I use two 500ohm/100W
wire-wound resistors for the R half of the RC filter.
On a different topic I got a used OBIT for $35, but it appears to be a
solid-state one running pulsed DC. The model is Allanson 2275-628G. 17.5kV
"peak", 45mA, at 20khz. I mainly bought this for curiosity to see how it
might perform on a coil. I'm a little suspicious of the voltage and
amperage, as the total VA rating is only 87.5VA - which is a fraction of
the 560VA that would be expected from 12.5kV RMS (17.5kV peak) at a full
45mA!
What experiences has anyone had with one of these?
Cheers,
Joshua Thomas
--
Joshua Thomas
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