The DW3 full wave directly heated rectifier was introduced by Mullard in 1931 and remained current production for some years.
Unlike our other DW3 this example has a clear envelope and the construction is visible.
The electrodes are supported by glass rods and a central support rod. No mica is used in the design.
The lettering is etched into the envelope dome. The filament is 4.0 Volts and the maximum anode voltage is 350 Volts to each anode.
The filament is an oxide coated ribbon held at the top by a spring. This filament is broken.
The second filament is intact and passes through the length of the blackened anode. The anode fin both connects to the support and adds an extra area to radiate heat.
The base pins are of the slit compression type.
The balloon envelope is 59 mm in diameter and, excluding the B4 base pins, is 128 mm tall.
References: Data-sheet & 1043. Type DW3 was first introduced in 1931. See also1931 adverts.
