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.

 
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	120	120	-10.7	3.3	0.45	1W

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This exhibit was last updated on 10 July 2005