The CV2218 is a half wave power rectifier based on the VX7074. The commercial equivalent is the R17 and the special quality version is the 6157.
The design was for a small size of rectifier for compact equipment. A pair of CV2218 rectifiers as a full wave rectifier would offer better performance than the 5V4G and take less room.
This rectifier has to be operated with a minimum of 50 Ohms of series resistance to limit the peak current. The maximum reservoir capacitor is given as 32 µF. The anode is taken to the top cap for additional isolation of the high voltage across the small envelope. The maximum PIV is 1,450 Volts and the peak anode current can reach 750 mA.
The stitched anode plates.
The The thick support wires are each connected to two base pins for good mechanical stability.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 61 mm tall.