The 5R4GYB is a high voltage power rectifier and was designed for industrial and military applications. It has a rating of 180 Watts. The maximum reservoir capacitor is specified at 4 µF and the rectifier needs a series resistance of 250 Ω to limit peak current.
See also5R4WGY for another version of this design.
The construction is housed in a glass tube with double mica sheets pressing against the glass to maintain rigidity.
The oxide coated ribbon filament is in the form of an inverted V and the folded anode is stitched together.
Unlike other versions of the 5R4GY the filament ribbon passes flat across the top mica and there is no tensioning spring.
The wide glass tube envelope is 38 mm diameter, and excluding the IO base pins, is 90 mm tall.
Reference: Datasheet Type 5R4GYB was first introduced in 1961.