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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 - EF50 Advert - EF50 Advert
    
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The EF50 was the ubiquitous red valve for a decade. Designed in 1938 by Philips of Eindhoven for Band I television receiver use and first released in 1939, this amplifier pentode was a general workhorse. 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.
he EF50 is an early all glass design as can be seen from the short pins and the metal base with centre spigot. The pins are equi-spaced around the circumference of the pin circle. Unlike the American metal valves, these have a glass envelope with a thin aluminium outer screening can.
The interesting fact for this exhibit is that this was made in America as Britain could not meet wartime demand.
The wide glass tube envelope is 33 mm in diameter and, excluding the B9G base pins, is 60 mm tall.
References: Data-sheet & 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 September 23, 2020.
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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