I think you've hit the important points.
Biggest mistake I see newbies make when tuning up amplifiers is watching
output and plate current while ignoring grid current, and cooking grids. I
watch output and grid current, and tend to ignore plate current, and my
3-500ZGs will probably outlive me. The pair of 3-500Zs in my old Henry 3K
(filament voltage properly adjusted!) were the same after 25 years as they
were when new....
WB2WIK/6
"Success is the ability to go from failure to failure with no loss of
enthusiasm." -Winston Churchill
> -----Original Message-----
> From: Pat Barthelow [SMTP:aa6eg@hotmail.com]
> Sent: Tuesday, February 11, 2003 2:33 PM
> To: amps@contesting.com
> Subject: [Amps] Operations/precautions Manual for Club
>
> 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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