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QP22B

Sensibly equivalent to:
240QP K77B
See also:
Quiescent Push-Pull
    
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The QP22B is a wonderful valve. It is a battery double pentode, designed for quiescent push pull class B audio amplification. The total power output is 1 Watt and was aimed at driving a loudspeaker, quite a luxury when battery powered.
The valve can be operated with automatic bias obtained from a resistor in the common HT negative lead. Such a resistor should be bypassed at signal frequencies by a 50 µF capacitor. For minimal distortion the total anode current (both anodes) should not fall below 3 mA and the screen grid supply should be 120 Volts.
The classic envelope is 38 mm in diameter and, excluding the B7 base pins, is 94 mm tall.
References: 1043. Type QP22B was first introduced in 1938.

 

Pin Connections
B7
1
2
3
4
5
6
7
g1(2)
g1(1)
a(1)
f
f
g2
a(2)

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
Pout
2.0
0.3
135
135
-11.7
3.8
0.5
1.33W
Updated December14, 2012.
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