> Yes there is a plate current position and it shows a definite rise in > current with modulation. There are dual 5U4's in the supply feeding the > finals and modulator and I swapped them both out with the same results. I am > leaning towards Gary suggestion that there is an impedance mismatch causing > excessive current draw. Does anyone have a 5100B or know what the impedance > of the primary and secondary should be. I will try another set of caps this > evening when I get home there are 2 , 40uf in series on the B+ line.
finding out what the final Z is, is as simple as using ohms law (close enough in this case) where R(or Z, if you prefer) of the final is equal to Voltage over Current. R=Ep/Ip. so, given that the Ep is 600VDC, and I'm guessing that Ip would be around 225mA R=600/0.225 R= (around) 2.7kOhms. Kinda low, actually. You'd need a modulater Z of around 2k. Sounds kinda like a 1:1.4 turns ratio is what's needed. 73 = Best Regards, -Geoff/W5OMR
