Tubes that test high?

[Axtman]

My go to tube tester is a B&K 747 dynamic mutual conductance tester. The "Good" scale goes up to 120. Every once in a while a tube will go higher than 100 and sometimes even higher than 120 (peg the meter). What does that mean?

[Enzo]

It means you are experiencing the limits of your system.

Tube testers are pretty good at finding bad tubes. They are not good at telling you a tube is good. A tube that seems to have a bit more than average is not generally a concern to me. The test is to use the tube in an amp. Does it act funny? Does it run away and refuse to reliably bias? Is it microphonic or noisy?

[The Dude]

Agree with the above. I wouldn't worry about it. If it does bother you, maybe try going through the calibration and see if that takes care of it. Calibration procedures are in the manual here:

http://www.mcmlv.org/Archive/TestEqu...r%20Manual.pdf