• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Screen Drive Push Pull ideas

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I've been looking at the *FJ7 tube. A pair of those look like they could be good drivers, especially with that hefty 10w side.

I was trying to modify an old Bogen MU15 to use 22JF6's as a guitar amp, but it wasn't happy. So I figure I'll use it as a mule for screen drive testing. I'm guessing the output transformer is rated for at least 15w. I'm not looking for horse power, just a proof of concept so I can better understand the circuit.

I didn't have any suitable transformers to provide 22v to the heaters so I bolted on a 40vac transformer and wired the heaters in series. Got nothing to loose. I get 20v on the heaters which I figure is good enough.

The power supply puts out about 400v on the B+. I figure this is good enough for 15w. I won't mess with 7W7's here. Just 6J6's and either a 6SN7 or a 6CG7 since there are already sockets ready to go.
 

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