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EF37A

Sensibly equivalent to:
5A/157D CV358 CV5080 OM5B
See also:
Evolution from EF36 & EF37 to EF37A - EF37A High Resistance Measurement Advert - The Williamson Amplifier
    
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The EF37A is a high gain, high impedance, pentode for use in AF pre-amplifier stages. The electrode system is of anti-microphonic construction, and the specially designed heater reduces hum to negligible proportions. This is achieved by a bifilar winding of the heater. Apart from the hum reducing construction the EF37A is the same as the EF36.
This valve was employed in the input stage of high quality audio amplifiers for many decades. The EF86 was the successor from Mullard.
The EF37A was also made with the classic shouldered shape of envelope.
The wide glass tube envelope is 29 mm in diameter and, excluding the IO base pins, is 84 mm tall.
References: Data-sheet & 1043 Type EF37A was first introduced in 1942.

 

Pin Connections
IO
1
2
3
4
5
6
7
8
m
h
a
g2
g3
nc
h
k

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
6.3
0.2
250
100
-2
3
0.8
2.5M
1.8
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated October 23, 2020.
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