[Amps] al811h reverse grid current

[gudguyham at aol.com]

No, one on each filament line feeding the tubes.  You could put another on the feed trace to the input of the inpu section.  Then you are fully covered.


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On Monday, February 23, 2026, 9:10 AM, Randall, Randy <Randy.Randall at UCHealth.com> wrote:

Jim would there be any practical gain in installing four GDT's instead of two on an 811H?

Thanks!

Upcoming out of office

Randy E. Randall AB9GO
Network Architect
UC Health
Randy.Randall at UCHealth.com
Desk Phone 513-585-7146
Cell 812-621-3884



-----Original Message-----
From: Amps <amps-bounces at contesting.com> On Behalf Of jim.thom jim.thom at telus.net
Sent: Sunday, February 22, 2026 1:12 PM
To: amps at contesting.com
Subject: Re: [Amps] al811h reverse grid current

****WARNING: This email originated outside of UC Health**** DO NOT CLICK links or open attachments unless you recognize the sender and know the content is safe.

From: "gudguyham at aol.com" <gudguyham at aol.com>
To: Curt Nixon <radio.ku8l at gmail.com>, Kurt Cathcart
        <Kurt at kuhlroad.net>
Cc: <Amps at contesting.com>
Subject: Re: [Amps] al811h reverse grid current

>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  each filament wire to ground. ?That?s the way it?s done.

Then also wire a 100K @ 3 watt  MOF directly in parallel  with each  GDT.
2 x GDT's required.  2 x 100 k resistors required.  GDT's are  160 V
rated.  Same as ameritron uses.

Jim  VE7RF
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