The EF11 is a variable μ pentode with a base that Tungsram describe as Footless.

The code EF11 is directly related to the Philips code scheme (as used by Mullard), the base fitting into numbers not used in the UK.

This valve was intended for the IF amplifier of radio receivers.

The metal envelope is 35 mm in diameter and excluding the Footless base pins the length is 37 mm.

References: Datasheet & ¹⁰⁴³. Type EF11 was first introduced^¶ in 1939.

 
Pin Connections

Footless	1	2	3	4	5	6	7	8
	g2	g1	k,g3,M	-	h	h	-	a

 
Absolute Maximum Operating Conditions^¶

Pentode	Vh	Ah	Va	mAa	ra	gm
	6.3	0.2	250	6	1.5M	2.2

Thanks to Frank Philipse for supplying the above PDF datasheet

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