The KT81 is the first M-OV kinkless tetrode audio power valve with a pressed glass foot. We can not find details of how it performed in the market place, but it was not a valve produced for many years.

Produced by M-OV this example is branded Osram and our other KT81 exhibit is branded Marconi.

The detail photograph shows the M-OV identification on the envelope.

The wide glass tube envelope is 31 mm in diameter and, excluding the B8B base pins, is 68 mm tall.

 
Pin Connections

B8B	1	2	3	4	5	6	7	8
	h	a	g2	ic	ic	g1	k	h

 
Absolute Maximum Operating Conditions

Beam Tetrode	Vh	Ah	Va	Vs	Vg	mAa	mAs	gm	Pout	D
	6.3	0.95	250	250	-4.4	40	7.5	10.8	4.3W	8%

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This exhibit was last updated on 24 November 2007