[sdiy] tube repair

[KA4HJH]

>> >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.
>>
>> It's worse than that. Once O2 hits the emission coating on the cathode
>it's
>> ruined.
>>
>Good point. I was thinking that the filament would be contaminated and would
>need to be replaced, but I forgot about the cathode coating. Nice catch.

I learned it all firsthand in neon school. During bombardment the cathodes
get red hot and the emission coating deoxidizes (forget  the correct term
for that). If the envelope is compromised you have to replace them and
reprocess the whole piece of tubing.

-- 

Terry Bowman, KA4HJH
"The Mac Doctor"