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