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Re: [Amps] Runaway Plate Current

Subject: Re: [Amps] Runaway Plate Current
From: "" <>
Date: Sat, 28 Dec 2013 17:26:39 -0500
List-post: <">>
Working on an amp at 1:30 in the morning?  ;-)

Seriously, I'm guessing the cause will be on a very short list
soon to be posted by the amp gurus here.

I'm curious to learn the reason as well - not that I'll ever be
brave (in my case crazy) enough to try to build what you have.

Trying to finish up my 6m Junk Box Amp. Quad 4x150a's, 1700v anode, ~355vdc
screen, ~ -55v bias. Input terminated in 50ohms, output terminated in
50ohms. Keying the amp with no excitation to adjust idle current all goes
well. Idle current adjustable from ~150ma to 400ma +. Screen current is ~
-8ma depending on idle current. Grid Current is 0. As soon as I unkey,
which removes the screen voltage, plate current goes through the roof
forcing an instant shutdown. Anybody have an idea what might be causing this

73, Roger


David (NOT Dave) Colburn, KD4E - Nevils, Georgia USA

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