The U74 was introduced during the first half of the 1940s. This half wave HT rectifier was later replaced by the U76 that had a rectified current of 100 mA.
The lower part of the envelope is covered internally by the getter deposit.
The front to back dimension is about 2 mm.
The cathode tube is rectangular. The heater wire is made from coiled wire coated with insulation. Two sections are wired in series with each of the four wires in the cathode laying side by side.
The classic envelope is 39 mm in diameter and excluding the IO base pins and spigot the height is 85 mm.
References: 1040. Type U74 was first introduced in 1945. See also1945 adverts.
