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CV358

Sensibly equivalent to:
5A/157D CV5080 EF37A OM5B
See also:
The World's First Computer
    
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The CV358 is high impedance screened pentode designed for intermediate frequency amplifier use the prototype was the EF37. The high anode AC resistance suggests the use of high Q tuned circuits.
The EF37 data sheet also gives parameters for use as a triode.
The first computer, Colossus, built for code breaking during WWII made great use of these valves.
Although the original computers were destroyed after the war, except for some that went to GCHQ, 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.
References: Datasheet & 1040.

 

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
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated October 05, 2013.
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