On Tue, 13 Oct 1998 07:24:07 -0700 Vic Rosenthal <rakefet@rakefet.com>
writes:
>
>The 3-500z in my SB1000 seems to be getting a little tired. It seems
>to take
>more drive to get less grid current and output then before, and power
>seems to
>drop off as it gets warm.
>
>I'm going to open it up (the amp, not the tube) and look around.
>While I'm at
>it, I'm going to bring the filament pins to the back of the chassis
>through a
>couple of 10k resistors so I can have a convenient place to check the
>voltage.
>
>My question is twofold: First, does anyone have a suggestion as to
>what to look
>for other than the tube? And second, if I do get a new tube, what do
>you
>suggest? Should I look around for a NOS Eimac tube? Are the Chinese
>tubes any
>good?
I seem to remember that you had problems with that amp in the past.
If the power decreases quite a bit as you go up thru the bands I would
suspect the tube. That amp and the AL-80 clones treat the 3-500Z very
rough.
Chinese tubes have been very reliable the past 3-4 years; buy from a
known source and just dont shop price. If you go graphite leave the fan
on for a good 3 minutes after RF use before shutting off the AC.
73 Carl KM1H
>
>Thanks,
>Vic, K2VCO
>Fresno CA
>
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>
>
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