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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
    
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The ubiquitous red valve, and this exhibit is clearly not in mint condition. This amplifier pentode was a general workhorse. It was extensively used in radio and radar during WWII.
Mullard, the UK arm of the Dutch multi-national Philips, describe the EF50 as being fully controlled by a grid voltage of 0 to -6 or 0 to -55 Volts, according to the circuit configuration.
The pins are equi-spaced around the circumference of the B9G pin circle. The central base spigot houses the evacuation seal as well as guiding the valve correctly into the base.
The wide glass tube envelope is 32 mm in diameter and, excluding the B9G base pins, is 60 mm tall.
References: Datasheet & 1043 et al. 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 August 23, 2013.
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