[Amps] Operations/precautions Manual for Club

[Steve Katz]

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 at hotmail.com]
> Sent:	Tuesday, February 11, 2003 2:33 PM
> To:	amps at 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 at hotmail.com
> 
> 
> 
> 
> 
> 
> 
> 
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