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[Amps] AL82 pi network C2 failure

To: "" <>
Subject: [Amps] AL82 pi network C2 failure
From: Rob Atkinson <>
Date: Tue, 7 Dec 2021 20:30:14 -0600
List-post: <>
My guess is that you are not sequencing your station, or you are, but
there's a timing problem.  When you run high power you have to have a
sequencer so everything that changes state can do so and pull in
before RF gets generated.   The idea is that for example, your
receivers mute, VFO comes on, receive preamps power down, antenna
change over happens, and any switching out at your antenna feedpoint
is done before the transmitter RF comes on.  Then when going to
receive, RF drops first, and everything else flips back over next.  It
seems like there's something hot switching, some relay maybe is a few
milliseconds too slow out at your antenna so for an instant, your
power amplifier sees an infinite impedance.   That will flash over
somewhere.  A vac. cap won't save a hot switched relay or contactor in
your system.  You need to delay your RF on make, and have it drop
first on break.

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