valve, tube, thermionic, electron, triode, tetrode, pentode, power,
magic eye, tuning indicator, nixie, history, data, data sheet,
specification, amplifier, radio, octal, B9A, B7G, B4, IO, KT88,
KT66, 12AX7, 12AY7, 12AT7, ECC81, ECC82, ECC83, 6L6, 6V6, EL34,
EL84, EM34, EM80, EM81, EM85, Mullard, Cossor, GEC, Gold Lion,
Marconi, Svetlana, Brimar, Ferranti, RCA, Sylvania, GE,
Heintz and Kaufman
This box still bears the 'Gammatron' label.
The Gammatron was Heintz and Kaufman's unsucessful attempt to
avoid the DeForest patents on the triode in the 1920s, but was long
gone by the time this box was made.