My first job at Bell Labs was working on the magnetron for the Nike search radar. Much of the work on microwave test equipment done at MIT's RadLab had not been reproduced by industry, so we had to make our own.
I retired from a job working for Ivan Getting, who had a lot to do with magnetron and radar development during WWII.
Varian was one of the contractors I assisted the Air Force with technical direction on traveling wave tubes for communication satellites. In the mid-1960's, I often went through the Varian cafeteria line with Sig Varian.
I still have a RF sweep generator which I built long ago, which mixed two X-band klystron's outputs to get 4.5 MHz output to align TV set's IF.
You can add the traveling wave tube, as well. There are still a few things that vacuum tubes do better than solid state!