Mazda QP.240 battery double output pentode valve (McVitie Weston valve collection), 1935
1935
1935
1910-1960
1906-1972
1990-1995
1996
1985-1995
1996
1986-1996
circa 1925
1981
1947
circa 1930; 1920
1922
2020
1986-1996
1980
1922
1977
1990-1995
1986-1996
1922
1986-1996
1986-1996
1986-1996
1986-1996
1992-1996
1923
1932
1901
1940-1960
circa 1925; circa 1925
1923-07
1912
1928
1952
1937
1932
1922
1835-1960
1948-1958
1951
1950
1840
1957
1957
1951
1953