The 7Y4 is an American design made in the UK by Cossor. The Marconiphone equivalent the U149 is basically identical.

The 7Y4 is a full wave rectifier.

The maximum reservoir capacitor is 40 µF and the minimum series resistance, for current limiting, is not given in the literature.

The wide glass tube envelope is 28 mm in diameter and, excluding the B8B base pins, is 55 mm tall.

 
Pin Connections

B8B	1	2	3	4	5	6	7	8
	h	-	a(2)	-	-	a(1)	k	h

 
Absolute Maximum Operating Conditions

Rectifier	Vh	Ah	Va	mAa
	6.3	0.5	325	70

Thanks to Frank Philipse for supplying the above datasheet

This exhibit was last updated on 05 July 2007 {find valves by name}