The CL4 audio output pentode was designed for singled use in universal mains receivers. The 4 Watt output was quite respectable.

The CL33 is electrically identical but has the more successful IO base. Whereas the pen36c is engineered on an English B7 base.

The classic envelope is 41 mm in diameter and, excluding the Ct8 base contacts is 120 mm tall.

 
Pin Connections

Ct8	1	2	3	4	5	6	7	8
	-	h	h	k	-	-	g2	a

 
Absolute Maximum Operating Conditions

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm	Pout	D
	33	0.2	200	200	-5.5	45	6	35,000	8.0	4W	10%

Thanks to Frank Philipse for supplying the above datasheet

This exhibit was last updated on 26 March 2008 {find valves by name}