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.The M-OV ellipse with the Type designation is on the envelope in thick ink.
The Marconi brand label.
The tape filament can be seen at the base of this image. The silver gettering made imaging the base of the anode difficult.The classic envelope is 45 mm in diameter and, excluding the B4 base pins, is 100 mm tall.References: Data-sheet, 1040 & 1043. Type U12 was first introduced in 1931. See also 1931 adverts. |
