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,6202, amperex, arcturus, brimar, channelmaster,
colvern, cossor
dario, debanks, edicron, ediswan, ei, elpico, emi
emston, era, eratron, ever-ready, ferranti, ge, gec
heinz, kaufman, haltron, hivac, hrs, itt, jackson
lamba, lorenz, marconi, mazda, mullard, national, osram
philips, rank, raphone, raytheon, rca, rft, selectron
sovtek, standard, svetlana, sylvania, telefunken, tronix, tungsram
united, valvo, westinghouse, zaerix
4CX250B 7203