Mazda QP.240 battery double output pentode valve (McVitie Weston valve collection), 1935
1935
1935
1910-1960
1906-1972
1922
1996
1985-1995
1990-1995
1996
circa 1925
2020
circa 1930; 1920
1986-1996
1947
1981
1940-1960
1922
1922
1990-1995
1977
1986-1996
1980
1932
1992-1996
1986-1996
1986-1996
1986-1996
1986-1996
1986-1996
1901
circa 1925; circa 1925
1923-07
1923
1912
1928
1951
1953
1939-03-28
1961-11-21
1939-07-24
1948-1958
1958 May
1951
1950
1957
1957
1952
1840