[Arran]

Russ;
 I remember bringing this issue up before when Jayce in Ohio mentioned running into many bad testing #26s and #45s on his tester. I can't speak for the early to mid 1930s tube testers, as I do not have one, but with just about any tester from the 1940s onward the heater/filament current drawing down the filament voltage can be an issue. I think this is because the designers of the testers assumed that when one was going to be testing a tube with a 1.5 volt filament that it was going to be something along the lines of a 1A7 or a 1C5, not a #26 tube, and the same thinking seems to have gone on when it came to the 2-2.5 volt tubes, that someone would be testing a #33 or a #34 and not a #45 or a #47.
  One my Stark/Marconi tester what I have to do on #45s, and other 2.5 volt AC tubes, is set the tester to the 3 volt range and then adjust the rheostat with a voltmeter using the pins in another tube socket, for some reason this does not work on a Triplet I have with the tube in place. On #26s I have to set the tester on 2 or 2.5 volts and do the same, as a #26 draws about 1.2 amps of current verses milliamps of current like a battery tube would.
   One other thing to watch for on early tubes, whether it be an AC or battery type, is bad solder joints on the heater pins, grid pins, or grid caps, all of those can cause the tube to test poorly if at all, this includes '01As.
Regards
Arran