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[Amps] Why does power output increase?

Subject: [Amps] Why does power output increase?
From: "jim.thom" <>
Date: Sat, 4 Jun 2022 08:35:10 -0700
List-post: <>
Date: Sat, 4 Jun 2022 13:26:32 +0000 (UTC)
From: "" <>
To: Shane Youhouse <>,  Victor Rosenthal 4X6GP
Cc: Amps reflector <>
Subject: Re: [Amps] Why does power output increase?

##  what is the idle current ???  Try it on SSB  (hi voltage)...and also on
CW  (low voltage).   IE: put xcvr on  SSB, mic gain on zero, key the PTT.

##  IF the resistor in the fil primary heated up, it's resistance would
INcrease, not decrease.   Tube emission would decrease.  PO would drop, not

##  Your bias vdc may be screwed up..and changing with a load applied.
Even this doesn't make sense.   Typ, when zeners fail, I believe they typ
fail shorted....which would result in sky high idle current. Which would
make it easier to drive the amp.

## But in this case, it's as though the zener V starts off normal, then
decreases, and I find that hard to believe.  Something else is amiss, and
it maybe one or both tubes has gone wonky.

##  do u have a dead on wattmeter to test with....or a scope ?

## The zener has to handle cathode current....which is the sum of the plate
and grid current.  I'd replace the zener with a string of  1N5408's.   I
have had no luck with zener's.

Jim   VE7RF
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