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EF50

Sensibly equivalent to:
63SPT ARP35 CV1091 CV1578 VR91 Z90
See also:
The Famous EF50 of WWII - Television RF Valve Development - Some Important British Valves - Pye B18T AC/DC Television Chassis - A General Purpose EF50 Circuit - EF50 Advert - EF50 Advert
    
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The EF50 was the ubiquitous red valve for a decade, and here we have a Mullard EF50 in a plain aluminium can.
The EF50 was designed in 1938 by Philips of Eindhoven for Band I television receiver use and first released in 1939. It was extensively used in radio and radar during WWII. One additional reason that so many existed was that they had a short life and so were changed often.
The can is stamped with two BBC valve section test stamps and shows that the BBC had this valve in 1951.
The wide glass tube envelope is 33 mm in diameter and, excluding the B9G base pins, is 59 mm tall.
References: Datasheet & 1040. Type EF50 was first introduced in 1939.

 

Pin Connections
B9G
1
2
3
4
5
6
7
8
9
h
g2
a
g3
s
k
g1
s
h

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
6.3
0.3
250
250
-2
10
3
1.0M
6.5
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated April 01, 2014.
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