[Amps] Gonset GSB-201 Mods

[KA9S - 2]

If you have any expertise with a Gonset GSB-201 amplifier, pleas lend me your insights.

I am getting a Gonset GSB-201 that has modifications. I don't have it yet so I don't know the extent of what was done to it. From the photos and the paint scheme, I can tell is was an original version, it now has 4 - 572B tubes in it, the HV power supply filter capacitors have been replaced with modern ones (on a circuit board), and the HV choke input filter choke is missing.

I have a manual that covers all the GSB-201 versions. Later versions substituted the 572B tubes for the 811A tubes but did not change the 1500 V power supply. I had been thinking that changing the HV supply from choke input to capacitor input would boost the HV up to 2100 V and eliminate the need for the 50k 100W load resistor (it adds 45W of extra heat). The increased plate voltage would allow the 572B tubes to run twice the power with the same final tank circuit load impedance.

The Questions:

Can the power transformer handle the instantaneous peak current demanded by a capacitor input filter? Can the final tank circuit components handle the increased peak RF voltage and current? (Blocking cap, plate tuning cap, HV DC RF choke). Has anyone done this successfully?

73s - Jeff - KA9S