I had the same experience in past.
In message "Re: [Amps] Doorknob quality"
on 09/02/22, "Edward Swynar" <gswynar@durham.net> writes:
: Hi Evert,
:
: Do not assume that merely because a capacitor like this may be rated for
: some 20-KV, it does NOT mean that it will be stable & suitable for use in a
: final pi-tank network...!
:
: I learned that the HARD way with my homebrewed amplifier here: as I keyed
: the rig, my RF output would slowly drop---and the plate / grid currents
: would (naturally) be all over the place.
I operated the contest as a guest op and there was a 8877 home brew
amp. While I keyed the amp, amp was going off tuned. I gave up use
the amp in the test.
After the test, we tried to find the reason why the amp going off-tuned.
YES, the padding doorknob caps would be hot by the RF current then
the capacitance was changed.
I'd like to know what kind of doorknob capacitors will be used in
the RF tuned circuit.
---------
Tack Kumagai JE1CKA/KH0AM
JE1CKA <je1cka@gmai.com>
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