Could you isolate it to one tube by carefully removing one plate cap at a time
(after the amp is dead and discharged; but you knew that) and firing it up in
standby? Maybe one tube is drawing more current than the other two.
I recently purchased a "Matched Quad" set of " 572b / 811H" from a California
outfit that were anything matched. One of the four tubes drew 1.0 amps of
plate current out of the box and, the other 3 tubes were all over the map with
grid current and plate currents.
I returned them at my expence the RF Parts only to have them ship me back three
of the FUBAR tubes and a different one that was as screwed up as the first
three.
Find your bad tube, substitute a known good one and see if the plate current
goes down in standby.
Mel
..
--- On Sat, 6/20/09, Larry K4AB <larry.k4ab@gmail.com> wrote:
From: Larry K4AB <larry.k4ab@gmail.com>
Subject: [Amps] Gettering 572B
To: amps@contesting.com
Date: Saturday, June 20, 2009, 9:56 PM
I noticed when gettering a new set of 572B's that I was drawing about 200mA
Ip during standby.
I quicky turned off the juice.
Questions:
1) Should I continue the gettering with the plate caps removed?
2) Is gettering even necessary with high quality tubes?
3) Are,(at least one of tubes) bad?
73,
Larry K4AB
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