Mazda QP.240 battery double output pentode valve (McVitie Weston valve collection), 1935
1935
1935
1910-1960
1906-1972
circa 1925
1922
1990-1995
1996
1985-1995
1996
1986-1996
2020
circa 1930; 1920
1947
1981
1986-1996
1980
1923-07
1990-1995
1986-1996
1922
1986-1996
1986-1996
1986-1996
1986-1996
1922
1977
1901
1932
1940-1960
1912
1923
1992-1996
circa 1925; circa 1925
1928
1951
1953
1939-03-28
1961-11-21
1939-07-24
1948-1958
1958 May
1937
1932
1922
1835-1960
1840
1952