Now, lets talk about something really important....like screen power supplies

[WD5JKO]

Clark,

   With a single screen dropping resistor off the HV B+, the screen voltage will try to go to full plate B+ in the absence of screen current, such as with no drive, or CW key up. So can the screen bypass capacitor take 2000 volts? Can the wiring? Can the Final Tube take 2000v on the screen? Using grid block keying, would the G1 cut off bias actually cut off the tube with HV on, and no drive?

   I understand what you are trying to do. Maybe you can figure a voltage divider to limit the CW key up G2 voltage instead of a single dropping resistor. Then think about what percentage of modulation you actually need at G2; It will be less than 100% even if the plate is modulated upward 130%. Also keeping the G2 modulation in phase with the plate modulation at the upper audio frequencies will need some thought.

Good luck with your project.

Jim
WD5JKO 

[ke7trp]

Jim. Thanks alot for the comments and Guidance!

I am doing this so I can run my Ultra modulation unit. You cant run it now with the Screen Self regulating. Robert is helping me with this project and has supplied the resistors, caps ect..  When I get the parts and his instructions, I will know more about how this will work.  We talked about this issue of the voltage and his system will track the Screen volts. I just dont know how at this point. We are changing the Bypass caps and such to larger broadcast types.  Its not just one resistor being installed.  As it is right now, The GK has no protection.. If you loose B+, The tube is probably toast.

If it does not work,  I will put it back to the way it was.. But it will be a learning experience.

Clark