The Z77 from M-OV was another designation for the ubiquitous EF91 of the early 1950s.

The design offers high gain, high impedance, high slope, in a screened pentode.

The electrodes fill the width of the valve. The three grids can be clearly seen and all grids have separate pins.

See also Z77 for a Marconiphone branded valve.

The thin glass tube envelope is 18 mm in diameter and, excluding the B7G base pins, is 46 mm tall.

 
Pin Connections

B7G	1	2	3	4	5	6	7
	g1	k	h	h	a	g3	g2

 
Absolute Maximum Operating Conditions

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm
	6.3	0.3	250	250	-2	10	2.5	1M	7.6

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This exhibit was last updated on 13 March 2006