This guy is instructing YOU on how to test a tube on the 539C but forgets to set the bias until after he has performed some of the testing. And, as mksj101 notes, he gives the wrong set voltage.
If you read the manual for the 539C, it states that you make final adjustments to the bias voltage AFTER you press P4. "In the column headed BIAS VOLTS is listed the exact voltage to which the BIAS VOLTS meter is to be set when testing a tube. Make final bias adjustment after the P4 button is pressed. " Middle of page 5.
That's why I like the 752 Hickok no need to switch sides can test both simultaneously. Unfortunately don't have the seperate transformers
This guy is instructing YOU on how to test a tube on the 539C but forgets to set the bias until after he has performed some of the testing. And, as mksj101 notes, he gives the wrong set voltage.
If you read the manual for the 539C, it states that you make final adjustments to the bias voltage AFTER you press P4. "In the column headed BIAS VOLTS is listed the exact voltage to which the BIAS VOLTS meter is to
be set when testing a tube. Make final bias adjustment after the P4 button is pressed. " Middle of page 5.