[AMPS] L-4B grid ckt shorts

Tue, 23 Sep 1997 07:38:10 +0000

> From:          "Ian White, G3SEK" <G3SEK@ifwtech.demon.co.uk>
> Subject:       Re: [AMPS] L-4B grid ckt shorts
> Date:          Sun, 21 Sep 97 21:49:35 +0000

> The same conclusion still applies, though. It seems incredible that so
> much grid current could be flowing in an oscillation condition. I mean,
> if that was the grid current, how big would the cathode current have to
> be... and where would it come from?

That's a good question Ian, since even 2000 volts of positive grid 
and anode voltage wouldn't drive that much current through the tube.

The peak emission current of an ideally constructed thoriated 
tungsten filament tube is just over 100 mA per watt of filament 
power. 

15 amperes at 5 volts is 75 watts. 75 watts times 100 mA is is 7.5 
amperes.

It's obviously not oscillations.

73, Tom W8JI

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