testing rectifiers in tube testers

[WSHU ENGINEERING]

----- Original Message -----
From: john w. king <jbkking at BELLSOUTH.NET>
To: <BOATANCHORS at LISTSERV.TEMPE.GOV>
Sent: Monday, January 14, 2002 3:14 PM
Subject: testing rectifiers in tube testers


> I have several 5U4GB rectifiers that I have tested on my B&K mutual
> conductance tube tester. All of the tubes check weak or QUESTIONABLE  on
the
> tester. Are tube testers relatively accurate indicators of the quality of
a
> rectifier tube such as the 5U4$GB . Whaty has been your experience? 73,
> John, K5PGW
>
John,

Most tube testers have a diodes OK line which is usually in the "BAD"
portion of the meter, if it reads above that line, then the tube is supposed
to be good. I agree with the philosophy that the only true test of a
rectifier is in circuit. put a volt meter on the B+ of a power supply under
load and compare the results of the tube(s) in question against a know good
or a new tube. You will usually see fairly radical differences on a bad
tube. The warm up characteristics are also an indication of how much life is
left in the tube. If a good tube brings the B+ up to snuff in under 30
seconds but another tube reaches the same voltage but only after 2 or 3
minutes of operation,  the slow tube is nearing the end of it's life even
though it still works.

73
Paul A. Litwinovich
Chief Engineer/ Webmaster
WSHU AM&FM, WSUF-FM
N1MUC
"RF IS GOOD FOR YOU"

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