The CY31 is a half wave rectifier on an International Octal Base. The design dates from 1939 and the CY31 was a replacement for the UR1. This design was made with both Ct8 (CY1) and IO bases.

The maximum reservoir capacitor is 32 µF and the minimum series resistance to limit in-rush current is 125 Ohms.

The anode seen face-on shows the wings on either side of the central circular cavity. The anode is blackened to aid radiation.

The classic envelope is 42 mm in diameter and, excluding the IO base pins, is 90 mm tall.

 
Pin Connections

IO	1	2	3	4	5	6	7	8
	ic	h	-	-	a	-	h	k

 
Absolute Maximum Operating Conditions

Rectifier	Vh	Ah	Va	mAa
	20	0.2	250	75

Thanks to Frank Philipse for supplying the above datasheet

This exhibit was last updated on 19 April 2008 {find valves by name}