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.
Sent from the all new AOL app for iOS
On Monday, February 23, 2026, 9:10 AM, Randall, Randy
<Randy.Randall@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@UCHealth.com
Desk Phone 513-585-7146
Cell 812-621-3884
-----Original Message-----
From: Amps <amps-bounces@contesting.com> On Behalf Of jim.thom
jim.thom@telus.net
Sent: Sunday, February 22, 2026 1:12 PM
To: amps@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@aol.com" <gudguyham@aol.com>
To: Curt Nixon <radio.ku8l@gmail.com>, Kurt Cathcart
<Kurt@kuhlroad.net>
Cc: <Amps@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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