[R-390] maintenance

[Ed Zeranski]

Neat post!

Age of New Old Stock does not appear to effect the life of tubes.

	I'm not sure what happened with a couple of sticks of 6C4s I had once. All
10 were NIB RCA but developed grid-cath probs after a few hours use. The RX
was an HQ-170A VHF. After using the NIB tubes and having the problem come
back I tried some old unboxed 6C4s and the RX was (is) fine. Going back in
to test all the NIB 6C4s in the set they all did the same to one degree or
another. Manufacturing?? Storage?? Don't know, they were a gift for doing
some BA stuff.


Do not just toss a tube because it has hours on it or even if it is noisy.

	Back in the '60s I swapped out a lot of 4-1000As from navaids because it
was FAA mandated. The used tubes were not turned in. An old guy knew my sked
and would always be waiting on my site on 'pull day'. Those tubes had some
hours but might still be Hamming today ~8^)

EdZ