The EF50 was one of the 'wonder' valves of WW2 making possible high frequency IF strips (45 MHz) for Radar. It was also a relatively short lived valve and was thus manufactured in vast quantities.

Here we have an example of one made by Tungsram.

The wide glass tube envelope is 3 mm in diameter, and excluding the B9G base pins is 60 mm tall.

 
Pin Connections

B9G	1	2	3	4	5	6	7	8	9
	h	g2	a	g3	s	k	g1	s	h

 
Absolute Maximum Operating Conditions

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm
	6.3	0.3	250	250	-2	10	3	1.0M	6.5

Thanks to Frank Philipse for supplying the above datasheet

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This exhibit was last updated on 19 April 2008 {find valves by name}