The ECC88 is a VHF double triode with separate cathodes. The ECC88 was designed for service as a cascode amplifier in the front ends of VHF radio receivers. One triode acted as the local oscillator and the other as the mixer (frequency changer).

The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 48 mm tall.

References: Datasheet & ¹⁰⁴⁰. Type ECC88 was first introduced^¶ in 1958.

 
Pin Connections

B9A	1	2	3	4	5	6	7	8	9
	a(2)	g1(2)	k(2)	h	h	a(1)	g1(1)	k(1)	s

 
Absolute Maximum Operating Conditions^¶

Triode	Vh	Ah	Va	Vg	mAa	gm
	6.3	0.365	90	-1.3	15.0	12.5

Thanks to Frank Philipse for supplying the above PDF datasheet