Westinghouse WL-787 "Demonstration Triode"
|The WL-787 tube was designed by Westinghouse as a classroom demonstration device in the late 1930's. The plate was coated with a phosphor which lit up when struck by electrons emitted from the multiple parallel filament strands. The action of bias voltage on the ladder-like grid, and external magnetic fields could be observed by watching the patterns of light emitted from the plate. The tube is about 10 inches long, and is 2 5/8 inches in diameter. The plate, itself, is 1 1/2 by 3 inches.|