Quote:
Originally Posted by Electronic M
Might want to watch the filament voltage when you test the 1V. Some testers depend on the filament current to load the filament supply to the right voltage. I don't know the filament current specks of the 1V so this might be an unimportant point.
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You raise a valid point. Sadly in my case my unit is just a tapped autotransformer, I have 1.4, 3.0, 5.0, 6.3, 12.6, 25, 50, and 115v filament voltage positions. Now I do have about 127 volts average (Did you know you can buy actual 130v incandescent lightbulbs? I learned that real quick after moving in here and going through too many normal bulbs in the first 3 months.) so I do use my variac when possible. Otherwise I warm a tube up on the next lower setting for 2-3 mins and if it tests marginal I'll bump it up to the listed position and see if it makes a difference. So far everything that tested marginal on the lower setting hasn't improved on the "listed" setting at 10% overvoltage average.
Now for something like a 35Z5 it lists the 25v tap position, so I don't bother warming it up on 12.6 because I'm still short 10v or so at the listed position. Some day I'll acquire an actual tube tester with lots of levers... Someday...
Related morning thought: 115v position, Was that really a common filament rating at some point in the 60s? It does have compactron sockets, and if anything was nutty enough to use a 115v filament (That wasn't a rectifier.) it'd have to be a compactron...