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EF91

Sensibly equivalent to:
5A/160H 5A/160K 6AM6 6F12 8D3 CV138 HP6 SP6 Z77
See also:
EF91 - not the valve that won the war - Television RF Valve Development - Valves and their Habits - Valves for Bands III, IV & V - The EF91 and the Blue Band
    
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GEC was the trade name of M-OV valves destined for the professional equipment market. The Type is given as EF91/Z77 as the EF91 was the generic name for this valve type.
It is a high gain, high impedance, high slope, screened pentode, primarily intended for use as RF amplifiers or mixer valves in VHF television receivers.
The GEC label.
The thin glass tube envelope is 17 mm in diameter and, excluding the B7G base pins, is 46 mm tall.
References: Data-sheet & 1040 Type EF91 was first introduced in 1947. See also 1947 adverts.

 

Pin Connections
B7G
1
2
3
4
5
6
7
g1
k
h
h
a
g3
g2

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
6.3
0.3
250
250
-2
10
2.5
1M
7.6
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated March 04, 2015.
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