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Re: [Amps] al811h reverse grid current

To: Curt Nixon <radio.ku8l@gmail.com>, Kurt Cathcart <Kurt@kuhlroad.net>
Subject: Re: [Amps] al811h reverse grid current
From: gudguyham--- via Amps <amps@contesting.com>
Reply-to: "gudguyham@aol.com" <gudguyham@aol.com>
Date: Sat, 21 Feb 2026 11:09:44 +0000 (UTC)
List-post: <mailto:amps@contesting.com>
You did it wrong.  The GDT do not replace the resistors on the grids.  You 
remove the resistors and the caps to ground  on each grid to ground on the tube 
socket.  You directly ground the grid.  Then one GDT goes from rad filament 
wire to ground.  That’s the way it’s done.

Sent from the all new AOL app for iOS


On Friday, February 20, 2026, 7:19 PM, Curt Nixon <radio.ku8l@gmail.com> wrote:

Look for a bad ground in the metering and or bias area.

On Fri, Feb 20, 2026, 7:12 PM Kurt Cathcart <Kurt@kuhlroad.net> wrote:

> Several months ago a seem to have a 572b go bad.  I replaced it and also
> replaced the resistors with GDTs (amoung other mods).
>
> Now I'm getting reverse grid current and the GDTs and lighting up.  I
> put in a net set of 572b and am getting the same thing, The view of my
> Sockets matches the picture on the Instructions .
>
> Advice?
>
>
> -Kurt
>
>
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