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21A6

Sensibly equivalent to:
CV5077 N152 N359 PL81
See also:
Series Pass Valves - Valves and their Habits
    
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The 21A6 is the Cossor implementation of the design that is also type PL81. It was designed for universal mains sets without a mains transformer and with the heaters on a series chain. The main design function was as a line output valve. It can also be used successfully as a series pass valve in stabilised voltage circuits. Such circuits place heavy demands on the cathode and so does the line output circuit where the valve effectively acts as a switch and draws heavy current when turned on.
As a line output valve in television service, the peak anode surge voltage is 7,000 Volts. The anode dissipation is 8 Watts.
The control grid is wound on copper rods for good heat conduction and these supports art topped with radiating fins.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 72 mm tall.
References: Datasheet & 1040.

 

Pin Connections
B9A
1
2
3
4
5
6
7
8
9
tc
ic
g1
k
h
h
ic
ic
g2
g3
a

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
21.5
0.3
200
200
-28.0
40
2.8
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated January 05, 2016.
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