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