144 MHz Kilowatt Amplifier with a Gu74b.

The Russian VHF tetrode Gu74b (Svetlana 4CX800) is rated 600W anode dissipation on the original datasheet and 800W by Svetlana. In my opinion these are very conservative values, in fact the tube behaves more like a 800 to 1000W dissipation. The devlopment of a compact amplifier using this tube was justified by its price and the possibility of low drive for full output.

Used in heavy EME since Jun. 1994

The outside look:

The plate cabinet:

This amplifier was somehow difficult to get stable with grid-1 input. It puts out 1.2kW with 20W of drive, 70% eff at 2.5kV plate voltage.
I will not publish this design since I do feel that it may be hard to reproduce for less experienced people. If you have any particular interest in this design please contact me by email.

Or if you really want to get serious with a "kW +" compact design, just wait for my "144MHz GS35b compact amplifier", under construction and expected to be presented very soon.

Any comments: Luis Cupido