[Amps] Excessive grid current - AL811HXCE

[Evert Bakker (PA2KW)]

Hi Martin,

I don't know which type of tubes this amp is using, but either it's
oscillation or it's DC drift due to unstable grid/screen voltage(s).

73's, Evert PA2KW   

-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Martin Kratoska
Sent: Sunday, May 18, 2008 14:09
To: amps at contesting.com
Subject: [Amps] Excessive grid current - AL811HXCE

A friend of mine has an AL811HXCE which started to behave wild. After
switching on, the amp works like a champ but after a warm up period the
grid current goes from normal 100-150 mA to that level which can't be
measured, the meter needle bumps to its stop. When switching off and
leaving a minute, the grid current returns back to normal (after a warm
up period it goes to wild values again).

I never seen this amp but collecting ideas what to do because I plan to
go there and help to repair it.

73,
Martin, OK1RR
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