Some of our sources suggest that the CV5281 does not have a direct commercial equivalent, however, the ECC84 is given as sensibly equivalent and the data given here is for the ECC84.

It is a pair of triodes separated by a screen and designed as a cascode amplifier for use in VHF receiver applications. The triodes are independent with separate cathode connections. The ridges on the top of the envelope suggest that this valve was made on a Mullard-Philips production line.

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

References: datasheet & ¹⁰⁴⁰

 
Pin Connections

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

 
Absolute Maximum Operating Conditions^¶

Triode	Vh	Ah	Va	Vg	mAa	ra	gm
	6.3	0.335	90	-1.5	12	4000	6

Thanks to Frank Philipse for supplying the above PDF datasheet