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14R7

Sensibly equivalent to:
CV3937
    
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The 14R7 is a screened pentode and double diode. This is the classic valve design for AGC rectification, signal detection and first audio amplifier. The 14R7 pentode is of the semi variable-μ type and thus can also function for IF amplification.The 14R7 has a 12.6 Volt heater - suitable for vehicle battery supplies, whereas the 7R7 has a 6.3 Volt heater for AC mains equipment.
The Brimar logo and Made in England. The diodes sit below the pentode on the common cathode.
Another view.
The wide glass tube envelope is 28 mm in diameter, and excluding the B8B base pins is 55 mm tall.
References: Data-sheet & 1040. Type 14R7 was first introduced in 1951.

 

Pin Connections
B8B
1
2
3
4
5
6
7
8
h
a
a(d2)
a(d1)
g2
g1
k
h

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
12.6
0.15
250
100
-1
6.2
1.6
1M
2.3
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated August 06, 2020.
shape:wide.glass.tube construction:all.glass type:double.diode.pentode age:1940.1950 base:b8b heater:12.6v pins:8 pin:1.h pin:2.a pin:3.a(d2) pin:4.a(d1) pin:5.g2 pin:6.g1 pin:7.k pin:8.h
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