The EF6 pentode was designed for radio receivers, where it would be used for RF and IF amplification. The later EF8 was a variable μ type for automatic gain control in IF stages.

Our other EF6 is un-screened but this one is magnificent in its red metallic screening paint.

This EF6 is new and the box gives the price as 11/6 eleven shillings and six pence and the purchase tax was 2/6 two shillings and six pence. The pre-decimal UK currency had the pound divided into 20 shillings and each shilling divided into 12 pennies.

The classic envelope is 29 mm in diameter and, excluding the Ct8 base pins, is 84 mm tall.

References: Datasheet & ¹⁰⁴³. Type EF6 was first introduced^¶ in 1938.

 
Pin Connections

Ct8	1	2	3	4	5	6	7	8	tc
	h	m	a	g2	-	g3	k	h	g1

 
Absolute Maximum Operating Conditions^¶

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm
	6.3	0.2	250	100	-2.0	3.0	1.0	1.75M	2.0

Thanks to Frank Philipse for supplying the above PDF datasheet

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