I've tested hundreds of picture tubes, but never run into this before.....
This picture tube is a 16WP4, in a Philco 51-T1607.
On setup, you set the G1 voltage at 45 volts, then turn the knob to increase the G2 cutoff voltage.....you turn the knob until it increases by two small divisions.
This Philco tube, I crank it all the way over, and it never increases. Yet, the tube tests good with the G2 cutoff cranked all the way.
The question is, is this tube good?
