06-16-2014, 08:44 PM
OK, here is what I've done.I took 2 of my globe spare 247s and tried them both on my 90B, which is in the good shape. The tubes were marked 400 and 1000 Mhos.Do not know which tester have been used.Long story short, both globes worked good. By good I mean the the audio volume and no distortion in comparison with my other good 47. What else should I expect other than volume level from the audio amplifier tube? Does it mean that I can use them as a good working tubes? BTW, I have a simple Knight 600, and it indicated 72 and 88 on them, chances are it is not calibrated.