There are some very interesting stories in the history of vacuum tubes. One is the 416A planar triode for the Bell Labs TD-2 microwave relay network: http://lo

There are some very interesting stories in the history of vacuum tubes. One is the 416A planar triode for the Bell Labs TD-2 microwave relay network: http://long-lines.net/tech-equip/index.html http://long-lines.net/tech-equip/index.html (I like especially the story of the terrorist attack on the microwave relay station by the "American Republican Army") Another is John Pierce on Klystrons and TWTs: http://www.smecc.org/john_r__pierce____electron_tubes.htm http://www.smecc.org/john_r__pierce____electron_tubes.htm