Valiant II screen supply

[W9BHI]

There is a 12K, 50 watt resistor in the screen supply to the 3 finals.
There are mods that state this resistor should be 15-20k to lower the screen voltage.
My question is: what should the value really be or better yet, what should the voltage ideally be.
(I have a new 20K, 50 watt adjustable unit.)
Also why does this resistor have to be rated at 50 watts?
Thanks guys,
Don W9BHI

[WQ9E]

Don,

I would stay with the original 12K as the designers intended.  This resistor will dissipate considerable power if excitation is lost as the clamp circuit goes into operation thus requiring a high wattage rating.

A modification isn't going to affect just one aspect of operation but unfortunately many modifiers ignore this simple truth.   The Valiant/Valiant II work fine on all modes with the existing 12 K resistor.

While working on your Valiant II I would suggest loosening the set screws in the flexible coupler that is part of the VFO drive.  As you know the Valiant is very heavy and when the Valiant is upside down and resting on the top of its front panel the flexible coupler will try to hold the panel rigidly in place and generally it will lose     The coupler can be repaired if broken but it is not a standard replacement item because the input and output shaft sizes are different.

[W9BHI]

Thanks for the info on the VFO shaft coupler.
I would hate to have to find another one of those.
I will leave the resistor alone.
It has been working fine the way it is.
Thanks,
Don W9BHI