I thought that might produce a reaction brickhistory. You are quite right, when I joined the RAF, I was trained on H2S Mk4A which was a 3cm Navigation & Bombing Radar system which used a cavity magnetron & a Klystron to obtain the IF frequency. They were used on wartime Lancaster & Lincoln Bombers.
There was three Lincolns still flying. By the time that I finished the Course, they had fall been flown to Northern Ireland to be scrapped !!