The Cossor 41MP is an indirectly heated audio output triode for mains powered receivers.

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.

In addition to seeing the wording etched into the dome of the envelope, this picture shows the box anode with open side mesh and the construction of the grid. Just out of sight is the oxide coating on the cathode tube.

The balloon envelope is 54 mm in diameter and, excluding the B5 base pins, is 112 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

More

This exhibit was last updated on 02 December 2007 {find valves by name}