GU-17 8wpc push pull transformer input

[Doug De Young]

Wanted to share this project I designed and built about a year ago.

I wanted to use the GU-17 a very cool tube. It’s the size of a el84 but has two plates and 2 control grids. It’s has only a single cathode and screen grid however.

This means a pentode push pull output stage can be designed with a single bottle. This little guy can make a pretty easy 8w maybe even 10w if pushed hard.

I also used a input transformer on this design. It’s not performing phase splitting duty this time though. Only voltage gain and loading the feedback network.

The driver and phase splitter is a LTP using a 6H8C dual triode.

For the power supply I used a capacitance multiplier for B+ and a simple regulator for the screen supply.

The output transformers I used are vintage units out of a GE receiver. They measure very well.

I’ve included the circuit and the PS as well as some FR/distortion/noise sweeps at 1,6&8w.

This amp also has clip indicating LEDs in the screen circuit. Very interesting to see how loud the amp will play before those light.

 

[v4lve lover]

COOL.


Looks like the russkies copied the QQE03/12.

 

[Doug De Young]

Yea, looks pretty identical.