[Amps] 2 x 4-250A Amp

[Peter Chadwick]

Tom said:
> and the screen needs 
regulated. It also needs a shunt regulator, or a series 
regulator with a heavy bleeder.  It also needs current 
limited.<
I've never seen negative screen current with 4-250As (as opposed to the 4CX, which is a totally different animal). My series regulator has about a 10mA bleed, which appears adequate. But I agreee with Tom that tapping down the electrolytic chain is not a good idea.
One way around the filament problem could be something like a 12 volt, 1 amp, centre tapped transformer. Connect the 12 volt winding across the 10 volts, leave the primary open (or use it for a bias supply, bridge rectified) and use the centre tap as the ground return. If you use a trifilar choke in the filament to get RF NFB,  the winding to the common point neeed not be as heavy as the other two windings, sinc eit will only carry out of balance current and the DC cathode current.
73
Peter G3RZP