The Cossor 41MP is an indirectly heated audio output triode for mains powered receivers. This exhibit is from later production as it is in a classic envelope and considerably smaller than the earlier balloon version of the 41MP.

The output load is specified as being 3,000 Ohms and the cathode resistor as being 320 Ohms. The valve through most of the time it was made was designed to produce 1.0 Watt at 5% distortion. In 1929 when the first 41MP's were sold the anode voltage was rated at 185 volts, the anode current as 10.5 mA and the output as 0.23 Watts. For these first valves the grid bias was -9 Volts.

The classic envelope is 44 mm in diameter and, excluding the B5 base pins, is 94 mm tall.

 
Pin Connections

B5	1	2	3	4	5
	a	g1	h	h	k

 
Absolute Maximum Operating Conditions

Triode	Vh	Ah	Va	Vg	mAa	ra	gm
	4.0	1.0	200	-7.5	24	2500	7.5

Thanks to Frank Philipse for supplying the above datasheet

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This exhibit was last updated on 03 January 2008 {find valves by name}