Ive used many, many, old date code pulls and NOS in the amp repair business
and Ive yet to find any 3CX800 with gas or seal leakage including some
stored for 20 or so years.
I have several of the 8873/8874/8875 family that all perform the same way.
The 4CX300A is notorious for leakage as is the glass-metal PL-172.
So there is a thread of truth to leakage but the rest is mythology found on
other forums from the great unwashed hordes from CB and FM.
Carl
KM1H
----- Original Message -----
From: "bob" <n612dw@gmail.com>
To: <amps@contesting.com>
Sent: Saturday, January 21, 2012 4:22 PM
Subject: [Amps] strategies for storing spares for maximum life ??
>
>
> Hi Gang,
>
>
>
> I have a pair of Alpha amps with 3cx800's in them. I like the tube/amps
>
> and the gain they have. Accordingly, I came across some spares (NIB Eimac)
>
> which I purchased, which as you know are rather expensive nowadays.
>
>
>
> What is the general consensus for the best storage strategy for preserving
>
> the life of the spares?
>
>
>
> Every once and a while, I come across something that indicates that the
>
> external anode ceramic/metal tubes likes these do not have as good a seal
>
> as is possible on the traditional glass envelope tubes.
>
>
>
> If this is correct, are we talking about limited shelf life of unused
>
> spares? Or is this just BS?
>
>
>
> For if they are limited life, and given the extraordinary life of them if
> properly
>
> cared for in amateur service, why then buy any spares (assuming one can
> still get them)?
>
> Hell, I may not need 'em for 10 years or more !!
>
>
>
> Since they are quite expensive, I am willing to do a little preventative
>
> maintenance if that is in order given it may be many years before they are
>
> needed. Therefore, what is best practice for preserving spares so they
> will
>
> still be good as new (which they are now) and ready to rock & roll when I
> need them?
>
>
>
> Some stuff I have read suggested that leaving them sealed up in a box
>
> is NOT the way to get maximum life out of them, but go no further to help.
>
>
>
> I have no idea what to believe, but I'm sure there are some resident
> experts
>
>
> on here how know a whole lot more about 'em than I. OTOH, I guess I
> could
> go
>
> out and buy some anti-aging miracle creams from one of those late night
> info-commercials, rub
>
> it all over 'em, and hope for the best too (Cosmoline? :-) ).. But I
> would
> think there is a
>
> better approach.
>
>
>
> A few things to start the discussion thread -
>
>
>
> Should I just leave them in the closet, or should they be exercised
> periodically
>
> in some manner?
>
> And if so, would it suffice to create a little jig with filament xfmr,
>
> socket, and proper cooling, or would B+ need to be applied to be helpful?
>
> Any sequencing needed? Like - filament first for N hours, followed by B+?
> Ramp up the B+ & current
>
> limit for glitches?
>
> How frequently should this be done?
>
>
>
> Position in storage make any diff? Vert/horiz ??
>
>
>
> Anything else/other???
>
>
>
> I'd prefer not to actually rotate them in/out of the amps if I can help
> it.
>
>
>
> Are there any differences between these things for external anode vs.
> traditional glass bottles?
>
>
>
> I know a little bit about getters/gassing and such, but really only via
> reading
>
> on the web.
>
>
>
> Oh oracles of the Order of the Valves out there. pse edumacate me with
> ur
> wisdom
>
>
>
> -bob
>
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>
>
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