Saga of the Vacuum Tube Book 1977 first edition first printing soft cover rare

Saga of the Vacuum Tube by Gerald F. J. Tyne. Blue cover vintage 1977 first edition first printing. 494 numbered pages. Clean and sound internally. There is some external edge/ shelf wear but still a nice clean copy. I have lots of electronic, radio, sound, recording, etc books pamphlets brochures and manuals to list. They all came from an estate of a local gentleman who was chief engineer at a radio station, had his own radio show and eventually had his own Christian radio station. Thanks for looking!