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CV138

Sensibly equivalent to:
6AM6 6F12 8D3 CV4014 EF91 HP6 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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The CV138 is a high gain, high impedance, variable mu, screened pentode. It could be used from AF to VHF up to about 200 MHz and was found in large numbers in most types of electronic equipment. In RADAR, radio & TV it was used for RF and IF amplification. It was also used for oscillators and frequency multipliers. The commercial equivalent is the EF91.
The envelope is silvered to prevent electron bombardment of the glass releasing gas.
This exhibit is dated September 1956 showing that it was in production for at least a decade.
The thin glass tube envelope is 18 mm in diameter, and excluding the B7G base pins is 48 mm tall.
References: Datasheet & 1040 Type CV138 was first introduced in 1947.

 

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 October 02, 2013.
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