TWTA RF Amplifiers Varian


K-rack Varian TWT amplifiers were very popular units for GHz frequencies. These deliver an easy 40Watts although the official spec's were 20Watt.

I have seen various Ham's owning such a tube but failing documentation on the spec's or the powersupply. Particular the powersupply is a sophisticated part of the unit and worthwhile to study. It's a well designed unit, but need some explanation when failing. At least it's possible to test the powersupply without the high voltage part.

Below you can find most of the information required to define the spec's of the tube and the schematic's for the powersupply. 



  1. Overview of tube's

  2. Configuration K-rack and type of tube used

  3. Principle diagram

  4. Schematic for high voltage part

  5. Schematic for voltage section

  6. Schematic for fault logic section

  7. Complete description of powersupply operation