[R-390] Tube testers and other babblings

[Joe Foley]

?
> 
> As long as the tester is OK, not much harm in
> testing them all, but keeping
> them on the tester too long is not a good idea. 
++++++++
Leave them in the tester long enough to let the tube
get up to operating temperature, I've had several that
tested good cold go bad when warmed up.



 You
> should test just prior
> to use, however, you might want to test them all so
> you will know how many
> good tubes you actually have on hand.
+++++++++
Nah, handling is tough on boxes, etc.  I'd test a good
selection of spares for quick emergency changes or hot
swaps but you'd have to test them just before using
them anyway to see if they went gassy.


  A few things
> to keep in mind:
> 
> 1.  Make sure the shorts lamp(s) work and always do
> the  shorts test first
> and make sure you watch and don't blink.  Unless the
> tube is of the
> do-not-tap type (like expensive 1L6's, and maybe the
> 26Z5W's) tap on the
> tube to watch for flashes.  
+++++++++
The military testers have jacks for plugging a headset
in parallel with the shorts lamp to listen for loose
elements or microphonic tubes.  Good idea!


> 2.  Triple-check that you have it set to the correct
> filament voltage.  Also
> a good idea to test in order of filament voltage --
> where applicable -- all
> the 6 volt, then 12, then whatever.  In other words,
> don't test the 26Z5W's
> first and then go to the others, if you think you
> might forget to flip the
> fil. switch.
+++++++++++
ARGH!  Good one, I did that!



> 5.  If the tester hasn't been calibrated, test the
> tester with known good
> tubes to get a general idea.  If it tells you a
> variety of good tubes are
> bad, it needs work or at least recalibration.  If it
> tells you all of your
> tubes or all of a type are shorted, that's another
> problem.
++++++++
Another good point about the military stuff, the
manual will have a good troubleshooting section, also
lots of people have worked on them.


> 
> Those are not particularly collectible in the real
> sense.  Older tubes from
> the 20's -- silvery 4-pin globe shaped ones may be,
> even if not working.
> Not necessarily all that expensive, though.
+++++++
Oh, yeah?

How much you give me for the ones I have?

Joe

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