Hi, QRZ i just finished assembly of my home brew amplifier and i am having some trouble diagnosing some issues on initial start up. I have a pair eimac 4-400a's grounded grid running 3400 volts on the plate 120 ma plate idle. and 225 ma plate curent drive. 4 ma on the cathode, with 50 watts drive from the viking ranger. One of the tubes turns bright orange with in 5 seconds of keying the rf the other tube shows no color or heat. I am attempting to use the original viking thunderbolt filament transformer which had a secondary winding for each filament and was fed 180 deg out of phase. I get positive 5.5 v ac across each cathode and 11v ac across both together. With the inner most filament taps connected together and floating above ground as the neutral. I also used a trifillar choke with a 3rd winding for the neutral wrapped over the standard bifillar choke sold by rf parts.