Tested on a minty Amplitrex AT1000 that went through a $500 upgrade by owner Chris at the CA factory.  Most all antique testers use lower voltages to test, not near actual operating conditions (that reveal much more accurate info about a tube performance.)  And with the 3% variance allowed on all the calibration voltages on antique testers (which can add up to a known 10% or more variance between "calibrated" testers) who knows what you're actually getting?

This one tests at 250Vplate or higher if selected so using the AT1000 at higher plate voltages than Hickok allows for much greater accuracy in results, 1% AT claims.  Tubes are more properly tested and will last longer and perform/sound better with tighter matching.

This black plate tube tests low, 46 and 40% of new, but decently balanced.  Tester in fixed bias mode, 250Vplate and -2Vgrid and measures the resulting currents.  Testing showed NO heater cathode leakage/short, low 0.1 gas, and NO noise with this tube.