Wade Bequest: DE6b triode radio valve with green tint
Wade Bequest: DER triode radio valve
Thermionic triode valve
Neutron thermionic triode valve
1930
KTD power amplifier
1918
Moorhead thermionic triode valve
1922
Thermionic triode valve
circa 1920s-1930s
Wade Bequest: DER triode radio valve
Wade Bequest: DE6 triode radio valve with blue tint
Wade Bequest: ORA triode radio valve
Ediswan thermionic triode valve
1923
Marconi thermionic triode valve
1923
Marconi thermionic triode valve
1927
Marconi Osram thermionic triode valve
1932
Marconi Osram thermionic triode valve
1927
Marconi thermionic triode valve
1943
Cossor thermionic triode valve
1932
Marconi thermionic triode valve
1923
Edison Swan thermionic triode valve
1932
Metropolitan-Vickers Cosmos thermionic triode valve
1923
Mullard Triode Valve MZ05-60
Marconi thermionic triode valve
1925
Metropolitan-Vickers thermionic triode valve
1925
Marconi Osram thermionic triode valve
1925
Marconi Osram thermionic triode valve
1925
Marconi Osram thermionic triode valve
1925
Marconiphone thermionic triode valve
1942
Mullard thermionic triode valve
1928
British Thomson-Houston thermionic triode valve
1924
Marconi Osram thermionic triode valve
1923
Thermionic triode valve
1924
British Thomson-Houston thermionic triode valve
1928
Metropolitan-Vickers thermionic triode valve
1925
Marconi-Osram LS3 triode, BBC-marked
Mullard ORA triode
Thermionic triode valve
Thermionic triode valve
Triotron thermionic triode valve
1935
Thermionic triode valve
Thermionic triode valve
Wade Bequest: DER triode radio valve
Wade Bequest: ONEVOLT ORA triode radio valve
Cleartron thermionic triode valve
1927
Marconi Osram thermionic triode valve
1935
Metropolitan-Vickers Cosmos thermionic triode valve
1925
Marconi triode valve
1931
Marconi thermionic triode valve
1940
Mullard thermionic triode valve
1923
Fellows thermionic triode valve
1923