[Amps] Alpha 76 input circuit ?

[Steve London]

I have recently converted an Alpha 76 to a pair of RFConcepts (Alpha) 
3CX800A7LG's . It is a little difficult to drive, taking every bit of 
100 watts input for 1500 watts output on the high bands. I am wondering 
if I could do better with a change to the input circuit.

The Alpha 76 input circuit was changed to the low-drive mod many years 
ago. The resistor pad measures about 95 ohms, so the resistors haven't 
drifted much. What about the toroidal transformer that Alpha used ? 
Without having to disassemble and reverse engineer it, can anyone tell 
me more about that transformer ? It seems that for a pair of 3CX800's we 
need to match the 50 ohm input from the driver to the ~28 ohm input of 
the pair of tubes. Yes, I know tuned input would be better, but that 
isn't going to happen.

BTW, other than the drive issue, I am very pleased with the RFConcepts 
3CX800A7LG's. When I did the conversion, I also added the K6XX grid 
current protection circuit.

73,
Steve, N2IC