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KT21

Sensibly equivalent to:
PM22D Pen231
    
Extras ▼

 

The KT21 was a battery output valve but not a beam tetrode valve. It was a modified version of the KT2 designed to be extremely economical in respect of anode current consumption and was intended to be used in sets which did not have a separate grid bias battery. The user penalty for these improvements was an extra 0.1A of filament current. It was designed for maximum amplification.
The classic envelope is 42 mm in diameter and, excluding the B5 base pins, is 100 mm tall.
References: Datasheet, 1040 & 1043. Type KT21 was first introduced in 1937.

 

Pin Connections
B5
1
2
3
4
5
a
g1
f(-),g3
f(+)
g2

 

Absolute Maximum Operating Conditions
Tetrode
Vh
Ah
Va
Vs
Vg
mAa
mAs
gm
Pout
2.0
0.3
150
120
-2.5
5.3
1.0
5.3
0.46
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated January 13, 2013.
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