The CV358 is high impedance screened pentode designed for intermediate frequency amplifier use. The high anode AC resistance suggests the use of high Q tuned circuits.

The data sheets also give parameters for use as a triode.

The first computer, Colossus, built for code breaking during WW2 made great use of these valves.

Although the original computers were destroyed after the war a rebuild has taken place at Bletchley Park. The red valves seen on the racks are the commercial EF37As. It is probable that the original machine was full of these grey valves in their service livery. Our example has the GPO batch number stamped on the external metalisation. Colossus was built by GPO engineers who must have chosen this valve in part for its low power heater.

The classic envelope is 29  mm in diameter and, excluding the IO base pins, is 85 mm tall.

 
Pin Connections

IO	1	2	3	4	5	6	7	8
	m	h	a	g2	g3	nc	h	k

 
Absolute Maximum Operating Conditions

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm
	6.3	0.2	250	100	-2	3	0.8	2.5M	1.8

This exhibit was last updated on 02 August 2006