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Re: [Amps]  Runaway Plate Current

To: Jim Thomson <>,
Subject: Re: [Amps]  Runaway Plate Current
From: peter chadwick <>
Date: Mon, 30 Dec 2013 11:03:00 +0100
List-post: <">>
I agree that biasing the control grid off is better.

Because of negative screen current, an active (rather than VR tubes or zeners) 
shunt regulator is best, and not difficult to do, although the heavy bleed 
current approach worked.

Question: Why do these modern ceramic tubes show negative screen grid current 
under some conditions? What is the mechanism that causes it? Straight 
thermionic emission from the screen seems unlikely, especially as a gold 
sputter would effectively prevent it.

73 es HNY

Peter G3RZP

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