screen / Hi voltage shut off.

[Shockwave]

You got the idea. You're right on the part number I gave. That transistor is the one I use for 100 volt steps with higher current. Also keep in mind if the screen voltage is present during standby, there will be continuous heat dissipation from the transistor because it is a shunt regulator. It will also need a dropping resistor in series with it to control the maximum current flow just like the zener alone would. The shunt regulator will draw maximum current with no load and draws less current as the tube draws more to keep the screen voltage stable.

 

[Crusher]

I looked up the the part # @ allied and didn't find it, so I went to mouser and did a search. The part I found seemed to fit the bill. I agree. It will need a nice chunk of heatsink. And the ceramic standoff insulator. Will have to figure out current, but I'm thinking a 100 ohm, 10W or 20 W resistor is gonna be a good start for a limiting resistor.

 

[Crusher]

I figure I'll use a 47 ohm resistorgoing from emitter to bottom of zener and other end of zener goes to base. Have a .01uf @3kv from screen to ground. Do you think it is necessary to run a small choke from collector to screen connection in order to keep rf out of transistor circuit? Do you think this is needed? I really do appreciate your help. Man you are a wealth of knowledge.