Wade Bequest collection of valves: R4 triode radio valve
1917
1917
1805-1845
1998
1998
1998
1898
1912
1933-08-15
1950-1960
c.1805
1787
1998
1998
1998
1998
1708-1714
1933-08-15
1787
circa 1987
1953
1971
1864
1891
1891
1880
1937
1798
1892-1902
1847-1859; 1878-1900
1998
1879
1983-09-08
1849-1851
1973
2000-11-23; 2001-01-11
1862
1980
1946-08-06
1914
1914
1852
1857