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Western Electric 'Doorknob' triode valve, type 316A, H4 base Science Museum Group © The Board of Trustees of the Science Museum
Western Electric 'Doorknob' triode valve, type 316A, H4 base, large-acorn type, marked 12163 and c.1453, filament broken, (RMW/Y240 - McVitie Weston number), by Western Electric Company, Inc, c.1936.