[Amps] testing 572 B tubes

[Peter Chadwick]

Rich said:
>Low emission causes gas ionization?<
The original questionner asked if maybe the tubes were soft. My suggestion was that if they weren't (no blue or purple glow between electrodes), low emission was a more likely cause of his problem.
If the tubes are low emission, then as 572Bs have a thoriated filament, it might be possible to rejuvenate them in the usual manner ( 150 to 200% filament volts for 5 minutes, 125% for an hour). Times and results vary a bit, and it doesn't always work. On the other hand, it can get a few more hours out of them.

73
Peter G3RZP