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28D7

Sensibly equivalent to:
CV945 CV946
    
Extras ▼

 

The 28D7 is a double beam tetrode designed to work as a class A audio amplifier. When both sections are used in push-pull the output is 175 mW. The anode and heater circuits are rated at 28 Volts. This is the voltage one would expect to find in a lorry or truck when the engine was running.
The twin electrode towers.
The side view of an anode plate. This is ribbed for strength and blackened to act as a more efficient heat radiator.
The wide glass tube envelope is 28 mm in diameter, and excluding the B8B base pins is 62 mm tall.
References: Datasheet & 3002. Type 28D7 was first introduced in 1943.

 

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

 

Absolute Maximum Operating Conditions
Beam Tetrode
Vh
Ah
Va
Vs
Vg
mAa
mAs
rk
rl
28
0.4
28
28
-
18.8
1.2
180
68,000
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated February 05, 2013.
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