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[AMPS] 3-500Z storage

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Subject: [AMPS] 3-500Z storage
From: (Bill Cotter)
Date: Mon, 24 Feb 1997 17:24:00 -0500

I have a Drake L4B that has been in the closet (sitting up as normal) for
over three years now and I just brought it out. I installed new 3-500z's in
about 1989-90 and am worried about the potential for problems. I also
replaced the diodes and filter capacitors about the same time as the tubes.
My plan was to bring up the HV supply slowly on a variac to "reform" the
capacitors and bring up the filaments to check the voltage on them. What
steps should I take to check for a gassy tube? Non-destructive steps :-)

If a tube is gassy, is there anything that can be done for them? ie:


Bill N4ALG


At 04:32 PM 2/24/97 EST, you wrote:
>Hello Robert and all.
>First of all the 3-500Z must be stored in a vertical position. Many
>friends have had the misfortune of buying a new set of spares only to
>find them shorted upon use many years later. All of them were stored on
>their sides. I'm not saying that it is a certantity, just that it does
>The gas factor is one that I have been unable to pin down, possibly
>others might wish to comment. What I have seen, on occassion, is a
>customer bring in an SB220 or the like that has been idle for many years
>that has a gassy tube. As near as I can discover they were all Eimac
>tubes with 1985-90 era date codes. Those old 1970's era tubes seem to be
>bullet proof. 
>Some of the early Chinese tubes had many problems which appear to be
>I hope this helps a bit.
>GL and 73   Carl   KM1H
>--------- End forwarded message ----------
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