The 6X5GT is a standard HT rectifier for low power AC mains driven equipment. The output of a centre tapped transformer would be applied to the anodes, the rating given is 325-0-325, the common cathode would be the output for the rectified voltage. A effective series resistance of 350 Ohms was required to limit surges and the reservoir capacitor had to be restricted to 16 µF. Nothing special and soon replaced by miniature valves of higher specification.
This exhibit is from Brimar and like all 6X5GT versions there is a common central cathode. However the anodes in this valve long side flanges and are mounted in an X formation one with the side flanges facing to the top and the other with the flanges pointing down. Thus unlike the 6X5GTs with small anodes stacked vertically this example manages extra radiating fin area. This example lacks any text on the base cap.
The stitched anodes.
Rotated through 90 degrees.
The wide glass tube envelope is 28 mm in diameter and excluding the IO base pins the valve is 67 mm tall.
References: Data-sheet, 1040 & 1043. Type 6X5GT was first introduced in 1936. See also1936 adverts.