George & Marijke Guerin wrote:
We tried
to make an 80 meter trap using a big high voltage 150 or 200 pfd door knob
and blew it up on the first test with power!! Three 75 pfd door knobs in
parallel or four 50 pfd door knobs worked OK for that trap with the
inductance trimmed to 80 CW
Boy, I can relate to that. I just put up a trapped inverted L for
160/80, using two 100 pfd 5KV doorknobs in parallel. Testing revealed
that when the power hit 500w CW, the heating caused the value to change,
and the SWR started sliding up, and up. I can only imagine what would
have happened if I had tried it at full power first.
Now I am looking for a LIGHT 200 pf capacitor that has a decent current
rating! I have some big micas, but they are much too big and heavy.
Vic K2VCO
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