Marconi Wireless Telegraph Company Ltd MTWC triode valve type DET 1
circa 1927
Osram valve
1955
Osram valve PX4 LH 10
1930
Marconi valve, type 4364F
1927
Thermionic valve - valve
1959
thermionic valve - valve,triode
1925
Thermionic valve - valve
1915
Thermionic valve - valve
1930
Thermionic valve - valve
1930
Thermionic valve - valve
1930
triode valve
1926
thermionic valve - valve
1921
thermionic valve - valve
1923
thermionic valve - valve
1923
thermionic valve - valve
1924
thermionic valve - valve
1915
thermionic valve - valve
1916
thermionic valve - valve
1922
thermionic valve - valve
1930
thermionic valve - valve
1923
thermionic valve - valve
1942