The M-OV B309 is labelled as MWT (Marconi's Wireless Telegraphy) and was sold for professional communications systems. It is a double triode equivalent to the Mullard ECC81. The device was designed for RF use and is of the low impedance type.

The thin glass tube envelope is 20 mm in diameter and excluding B9A base pins the length is 48 mm.

 
Pin Connections

B9A	1	2	3	4	5	6	7	8	9
	a(2)	g1(2)	k(2)	h	h	a(1)	g1(1)	k(1)	hct

 
Absolute Maximum Operating Conditions

Triode	Vh	Ah	Va	Vg	mAa	ra	gm
	6.3	0.6	250	2.0	10.0	10,000	5.5

Thanks to Frank Philipse for supplying the above datasheet

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This exhibit was last updated on 05 July 2007 {find valves by name}