The U12 directly heated full wave rectifier was a popular design that was also produced by other manufacturers.Initially the U12 and the U14 were the same valve. However, some valves performed better than others on final factory test so the best ones were graded and marked U14 whilst the also-rans were marked U12.In the picture the type designation on the top of the envelope has the central type number omitted. The Type Number U12 is stamped (not etched) in large white letters on the side.The classic envelope is 48 mm in diameter and, excluding the B4 base pins, is 105 mm tall.References: Data-sheet, 1040 & 1043. Type U12 was first introduced in 1931. See also 1931 adverts. |
