[sdiy] tube repair

[Travis Shire]

> Perhaps I should just throw it away to keep me from lamenting, but I broke
a
> gold-pinned 6922 a while ago. I was really looking forward to using this
as
> the first 2 preamp stages in a hi-gain, 2xEL84, 100% (or close) 10 watt
amp.
> I can't remember what the make was - it got wiped off when I cleaned off
> thebasement grime that had accumulated., but I know it was "made in
> Holland", so Philips is a good candidate. Anyway, only the top gas purge
nib
> and a bit of glass aroundit broke. I figured a skilled glass blower could
> fix the glass work easilly. Heck the tube even had the look of being
> hand-made by a glassblower (the way the body dipped in the middle that was
> slightly irregular). As for the getter: what do they usually use? I have a
> small lanthanum rod in a vial. I wonder if it reacts with oxygen well
enough
> to "get" that last bit of O2. How do they "flash" the getter? Does it
happen
> during the final joining of all of the glass parts or does the vaccuum do
it
> or is it a combination of both? Is it really worthwhile to fix a broken
6922
> with gold pins, or should I just tosse the thing or make one of my little
> "Cornell" boxes out of it like I did with a broken EL84 among the other
> EL84's I found when cleaning out my basement.?
>
> cheers,
> aa
>
You can't repair a broken tube. Even if it *was* possible...it would be cost
prohibitave. The getter is flashed with RF energy after the tube has been
vacuum pumped and sealed.
Check out this video of a guy in France who "rolls his own" directly heated
triodes. That should give you an idea of how its done.
http://groups.google.com/group/alt.guitar.amps/browse_thread/thread/4a55581875ecf044/3aa47a8e4fd93149?hl=en#3aa47a8e4fd93149
Also that usenet group is a better place to post tube related questions. And
also see rec.audio.tubes