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EF55

Sensibly equivalent to:
CV173
    
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The EF55 pentode is physically the big brother of the EF50 with which it shares common base connections. The EF55 is a single ended RF pentode with very high mutual conductance and a sharp cut-off. It was designed for video frequency use, probably in RADAR service, and its service code was CV173
It is an early all glass constructed valve with equi-spaced pins and a spigot for location into the valve holder.
The current rating places it as a power valve but it is designated for amplifier service with a medium anode impedance.
The outer aluminium shield is 33 mm in diameter. The overall length excluding the B9G base pins, is 79 mm.
References: Datasheet & 1040 Type EF55 was first introduced in 1946.

 

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
1.0
250
250
-4.5
40
5.5
55k
12.5
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated December26, 2011.
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