The 5U4G rectifier delivers 100 Watts of DC power. It would be used for all types of medium power equipment.
This standard rectifier was made by several manufacturers. Here the elliptical lozenge containing the Type designation is obviously an M-OV product.
The overprinting repeats the 5U4G and adds the up arrow and CV1071. The absence of explicit branding is to be expected on a valve delivered to the UK Government.
The twin rectifier sections separated as widely as possible in the envelope.
The top mica that holds the electrodes firmly in place and grips the glass. Inside the hooks of the tensioning springs can be seen the oxide coated filament ribbons.
The classic envelope is 50 mm in diameter and, excluding the IO base pins, is 109 mm tall.
References: Data-sheet, Data, 1040 & 1043. Type 5U4G was first introduced in 1938. See also1938 adverts.
