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EF50

Sensibly equivalent to:
63SPT ARP35 CV1091 CV1578 POVT207 VR91 VT-250 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
    
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The EF50 was one of the 'wonder' valves of WWII making possible high frequency IF strips (45 MHz) for Radar. It was also a relatively short lived valve and was thus manufactured in vast quantities. Known as a red valve, this clone made by Cossor shows that plain canned vessions also were made.
This amplifier pentode was a general workhorse. It was extensively used in radio and radar during WWII.
Mullard, the UK arm of the Dutch multinational 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 dimensions are 32 mm in diameter for the body of the screening can, and 60 mm in length, excluding the short pins and the central spigot that locates the pins and covers the evacuation seal, as well as providing a connection for the screening can.
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 December03, 2012.
shape:wide.glass.tube construction:all.glass type:pentode age:1930.1940 base:b9g heater:6.3v pins:9 pin:1.h pin:2.g2 pin:3.a pin:4.g3 pin:5.s pin:6.k pin:7.g1 pin:8.s pin:9.h
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