Two 15GP22s At TheBay

[Phil Nelson]

Testing an unknown CRT is certainly a common scenario. Perhaps one of the sages could tell us all what the potential risks might be.

Phil Nelson

[Phil Nelson]

Originally Posted by Phil Nelson

Testing an unknown CRT is certainly a common scenario. Perhaps one of the sages could tell us all what the potential risks might be.

So, what is the layman's answer to this question? If you fire up an unknown CRT on a tester, are you risking anything for a future rebuild? Or do you just go ahead on the theory that the damage (if any) has already been done?

Phil Nelson

[andy]

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[Phil Nelson]

Originally Posted by andy

simply applying HV to the CRT while the socket pins are grounded will tell you if it's very gassy.

What would you look for to tell if it's gassy? Glowing fog or other light show in the neck? Sorry to be so dense, but I haven't tried any of these experiments -- or had a gassy CRT, for that matter.

Phil

[andy]

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[sweitzel]

Seller updated one of the auctions. Looks like someone was able to visit the seller and test the CRT's One of them is good with great emission! The other has gone to air. If the buyer of the So cal set wins the good CRT we might have another living CT-100 soon!

[jr_tech]

Originally Posted by Phil Nelson

So, what is the layman's answer to this question? If you fire up an unknown CRT on a tester, are you risking anything for a future rebuild? Or do you just go ahead on the theory that the damage (if any) has already been done?

Phil Nelson

If you fire up a gassy CRT at full heater voltage, it is very likely that the heater will quickly burn out. Since the heater and cathode are replaced during a rebuild, it is unlikely that a future rebuild would be adversely affected by doing so.

However, once the heater is burned out, a rebuild would be the ONLY option. No possibility of a rework (however slim) would exist. I guess that I would prefer to leave as many options open for as long as possible. Perhaps an attempt to seal the leaks followed by a getter re-flash and cathode re-activation could still rescue the tube, as long as the heaters remain intact. However, this is very unlikely and perhaps a waste of time and money, but at least the option remains open. If I had access to an RF generator and a getter "wand", I would try a getter re-flash in a New York Nanosecond... not much to loose!

jr