[Amps] door knob capacitors

[Rob Atkinson]

Yeah but how do you tell a fleamarket doorknob is okay for RF.  If you
have a lot of do re mi and can get them new I guess it's easy, but
your typical $2 doorknob in a box sitting on the pavement in a parking
lot is a different situation.  The markings are often cryptic and vary
by mfr., -- It's better to be safe than sorry.  OTOH, I did not know
micas, eg. the big brown jobs with the binding posts on top ever
leaked.   I test mine with my el cheapo Eico 950 cap tester, one of
those things with the magic eye tube but it only puts up to 500 v. on
one.  If it says a cap is good, I'm not sure it is really good or not
except the eye opens up at or near the spec'd value.

So I'm not sure what to reccomend for 160.  I thought the 1 MHz tx
micas were a safe bet.   the trick is getting them to fit inside.
Some amps are cramped for space.

The Centralab doorknob I used was about 3/4 inch diameter coated with
blue green glaze and 250 pF at 20 KV.

Rob
K5UJ

<<<
Rob,

It depends on the capacitor. The ones intended for high RF
currents are marked to show the maximum reactive current
they can handle. Some time ago I had the same experience
as you, with a cap literary exploding. Now I use only caps
that are spec'd for high RF current. I have had no trouble
wiht those.

73,

George, AA7JV
>>>