AF triode valve (McVitie Weston valve collection), 1906-1972
1906-1972
1906-1972
1920-1933
1920-1940
1900
1955
1914-1945
1889-1900
1935
1907
1955
1913-1914
1906-1908
1900-1920
1900-1920
1936
1930-1950
1920-1940
1905
circa 1934
1932
1979
1900-1919
1958
1931
1935-1955
before 1889
1940-1970
1911