[Antennas] Checking 3-500 tubes

2002年6月10日 09:32:15 -0400

K0CQ and other comments are excellent suggestions and I have one more to
offer. be careful about using the sb220 as a test fixture. the tubes can
test ok with a VOM for grid to plate short but be gassy. hence they will
only exhibit the nasty short condition with high voltage. with the sb220,
you can either apply high voltage or not - nothing in between.
bill at omega electronics has a refinement. he has the high voltage
transformer primary on a variac and brings high voltage up slowly after the
filament/cathode have had ample time to warm up. as voltage increases, he
monitors the color in the tube. if he sees a blue glow, he shuts down and
declares the tube gassy. this prevents blowing components.
found this all the hard way, had an old 3-500 amp that had not been used for
some time. fired it up and KABOW. gassy tubes.
the alternative is to use a hi-pot test fixture but these are hard to find.
jim
N1NK
----- Original Message -----
From: <[email protected]>
Cc: <[email protected]>
Sent: Sunday, June 09, 2002 9:18 AM
Subject: [Antennas] Checking 3-500 tubes
> To all:
> I ran across 3, 3-500 tubes made for the SB-220 (and other) amps. I need
to
> check these tubes the easiest way. Is there a way of checking these tubes
for
> worthiness with a VOM meter or would I have to put them in an amp under a
load? I
> do have an SB-220. Any comments would be useful. Thanks for your for your
help.
> GT
>> - - -
>> Your moderator for this list is:
> Larry Wilson KE1HZ [email protected]
> _______________________________________________
> Antennas mailing list
> [email protected]
> http://mailman.qth.net/mailman/listinfo/antennas