AF triode valve (McVitie Weston valve collection), 1906-1972
1906-1972
1906-1972
1935
1920-1933
1936
1889-1900
1955
1930-1950
1900-1920
1920-1940
1920-1940
1907
1914-1945
1905
1922-1929
circa 1934
1900-1920
1955
1900
1913-1914
1906-1908
1932
1933
1933
1979
1940
1940-1970
1931
1900-1919
1958
1911
before 1889
1935-1955