AF triode valve (McVitie Weston valve collection), 1906-1972
1906-1972
1906-1972
1920-1933
1900
1889-1900
1920-1940
1955
1907
1914-1945
1935
1920-1940
1936
1930-1950
1913-1914
1900-1920
1900-1920
1906-1908
1905
1900-1919
1979
1932
1955
1958
1931
1935-1955
1911
before 1889
1940-1970