8bp4 tube test on 7vt5a2 motorola.

[kvflyer]

Originally Posted by Zenith26kc20

Electrostatic tubes suffer from ion burn over the entire face. There is no ion trap nor are they aluminized. As the phosphor degrades over time the electron gun can still be good but the phosphor will get dimmer from ion bombardment. My 8jp4 is bright and clear. The set it came from probably failed early on. Some of my 7jp4 tubes have to be watched in the dark.

As they say, "What he said ^^^". Totally my observation as well.

[fumplet]

Trying to recreate bandersons diode ballast with the 2 diodes, 47 ohm, 22 ohm, and cl 90 thermistor. I was under the impression that this would be a plug and play ballast yet my 9t1 chassis has no connection to pin 8 of the ballast tube socket. I believe one end of the cl 90 is in pin 8 or am I wrong? Do I need to run the power to pin 8?