[AMPS] explain this one

[Bill Vogler]

Ladies and Gentleman:

The saga continues with my amplifier recently purchase Amp Supply LK500-ZA.
I received a very helpful response from a member in this group familiar
with the amp and I have decided to replace the padding capacitors in the
tank circuit.

As I mentioned in the 1st post, one of the 160 meter padding caps was
fried/burnt which is located on the Load side of the PI circuit. I also
mentioned that the previous owner mentioned that when operating on 10
meters he smelled something burning. I did not believe that the particular
160 meter capacitor that showed signs of burning was related to the 10
meter problem since the capacitor was not physically connected when
switched to the 10 meter position. 

So I connected a dummy load and transceiver to the amp and plugged it in
and tuned it up on 10. After getting a good match I left it key down for a
few seconds and sure enough I WAS WRONG. The 160 meter capacitor started
smoking

I am at a loss for an explanation on this one. When switched to 10
meters/AUX, the 160 meter capacitor in question is out of the circuit. I
checked the bandswitch wafer(s) and there is not a short or problem,
everything checked out like it should have (or at least I think).

The 160 capacitor is connected to a beefy wire that is connected between
the wafer and a side wall. This lead is long and goes across the top of the
variable Load capacitor in the PI/Tank circuit. I might also mention that
the tube is running much hotter at 10 than on the other bands, the outer
case above the tube is uncomfortably hot.

My only guess/explanation is that there some type of coupling going on and
the only way this could happen is at a very high frequency. Did I inhale
too much of the burning capacitor? I feel like changing my call to
kr6ack!!!

73s

Bill, w6qd

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