[Amps] al811h reverse grid current

[gudguyham at aol.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.

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On Friday, February 20, 2026, 7:19 PM, Curt Nixon <radio.ku8l at 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 at 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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