The EBF89 features two signal diodes and a variable μ pentode in the one envelope and sharing a common cathode. The diode anodes are small plates placed either side of an extended cathode tube.

The variable μ characteristic is indicative of a device designed to have its gain controlled by an AGC system. This places this valve in service as a final IF amplifier and detector. The high impedance of the pentode supports the case for use with a tuned circuit connected to the anode.

The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 57 mm tall.

References: Datasheet & ¹⁰⁴⁰. Type EBF89 was first introduced^¶ in 1958.

 
Pin Connections

B9A	1	2	3	4	5	6	7	8	9
	g2	g1	k,s	h	h	a	a(d1)	a(d2)	g3

 
Absolute Maximum Operating Conditions^¶

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm
	6.3	0.3	250	100	-2	9	2.7	1M	3.8

Thanks to Frank Philipse for supplying the above PDF datasheet

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