Hello Folks,
I am tasked with writing a operations manual for our club station on the
Monterey Peninsula for a soon to be larger group of relatively new hams. We
have and will emphasize HF operations and have a number of KW level
amplifiers, mostly 3-500Zs in grounded grid. (Drake L-4, Heath SB 220 and
some Homebrew 4-400As in GG.
I want to develop a intro manual for the new Amp user, with the objective of
preventing/minimizing of operator errors that destroy the amps. I would
welcome input from seasoned hams that can tell me what to focus on, as far
as the most common operator mistakes that can cook a 3-500Z amp. I have
used them for decades, so I don't know what kinds of mistakes the newbie QRO
operator is likely to make. For 3-500Zs, the most obvious things I would
think of is watching grid current, ensuring adequate loading during tuneup,
quick achievement of resonance, watching for correct antennas and band
switch presets, and, to a lesser degree, watching Plate current maximum
value.
Also, since the L-4B and the SB 220 were really designed during the 1KW
INPUT limits era, what would be the recommended maximum power output level
to use, now, with 1.5KW out being the limit, say in heavy duty cycle use, as
in contesting? Can the L-4B power supply and amp handle reliably 1.3KW
output, CW? SSB? How much for RTTY? The power supply seems beefy. The SB
220, less so.
I liberally use muffin fans on the cabinet above the tubes, and in the
Drake, on the power supply cover.
Your input greatly appreciated.
Pat, aa6eg@hotmail.com
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