RCA 21AXP22 picture tube/rebuilt picture tube

[NewVista]

Quick confirmation needed here.

When I fixed the flyback on my CTC-5, 21AXP22A guns started to glow neon blue & red. I had assumed the tube would have been fine but now tested it and filaments light nice deep red (meaning air not a problem ? as I would expect warmer orange color with air present ?)

On B&K tester a "short" shows up (in fact a 68 k ohm leakage heater-to-blue cathode)
B&K book said in this case use an isolating filament transformer - which I did but same symptoms --- and, by the way, ZIP in the way of Emission.

So is it air ? Who rebuilds these now?

[jr_tech]

Originally Posted by NewVista

filaments light nice deep red (meaning air not a problem ? as I would expect warmer orange color with air present ?)

Sounds to me as if the tube has become gassy.
What happens is the gas conducts heat away from the filament, and causes it to run cooler, hence the darker/dimmer red color. Now this may seem bass ackwards, but the heater is more likely to burn out when it is running this way because the resistance of the cool heater is much lower than when it is at normal operating temperature, so that it will blow out like a fuse that has excessive current running through it.
sad,
jr

[miniman82]

Originally Posted by NewVista

Who rebuilds these now?

No one, like I said join the litany that is sad AXP owners praying for a rebuilder.