[Amps] Henry 2K conversion to 3-500Z

[Fisher, Benjamin J]

Hi All
I'm wanting information that will guide me in the conversion of an old original Henry 2K from 3-400Z to 3-500Z. I have searched the archives and found some information but not quite enough. I understand there is some kind of bias that must be added. There is mention of using a 50 watt zener somewhere to do this but I have been unable to find any details. Help would be greatly appreciated.
73
Ben K9BF