Folks,
He might want to check the molex connectors between the front panel and the
deck. I had one where they loosened-up and gave erratic meter readings.
(The grid meter would peg)....
73, George
K8BRW
----- Original Message -----
From: "Tom Rauch" <w8ji@contesting.com>
To: <amps@contesting.com>; <nospam4me@juno.com>
Sent: Saturday, June 02, 2001 8:08 PM
Subject: Re: [AMPS] continued Alpha work
:
: Skipp,
:
: > I've relayed to Bob about checking the blocking caps
: > and the tank alignment. He has done said with no
: > positive results. Here is his latest text to me. I'm in
: > the process of relaying some of the amps members
: > posts back to him.
:
: All of that is a waste of time, if indeed he has high grid current AND
: high plate current at the same time.
:
: Open blocking caps cause low plate current and high grid current.
:
: Misaligned tanks cause low plate current and high grid current, or
: high plate current and low grid current.
:
: High grid current comes from a lightly loaded plate circuit----one
: running the tube into a much HIGHER than desired load
: impedance.
:
: High plate current with a shallow dip comes from running the anode
: into a LOWER than desired anode load impedance, and that
: means you can't have excessive grid current.
:
: When you see high plate current and high grid current with a
: shallow plate current dip as you indicated, it is a dead-giveaway
: the metering system is messed up.
:
: If the metering system is messed up and he is trusting it to tune
: the PA, that explains why the output is low. More than likely the
: grid meter is partially reading plate current through a fault in the
: from the B- return to the chassis. When that condition exists, the
: user will "overcouple" the PA because he "thinks" the grid current
: is higher than it really is.
:
: When he overloads the amp to reduce grid current, he will have low
: output, a shallow plate current dip, and at the same time the grid
: meter will (because of the fault) show excessive grid current that
: really isn't there.
:
:
:
:
:
: 73, Tom W8JI
: W8JI@contesting.com
:
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