The EM87 tuning indicator uses the closing bar principle and is housed in a standard miniature valve envelope.

This valve has the same base connections as the EM85E and differs in sensitivity, anode voltage and anode current. The manufacturers short form catalogue lists both as tuning indicators and gives no guide as to differences. The base connections are also the same for the popular EM84, although this has a much greater voltage range.

The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 65 mm tall.

References: Datasheet & ¹⁰⁴⁰. Type EM87 was first introduced^¶ in 1961.

 
Pin Connections

B9A	1	2	3	4	5	6	7	8	9
	g1	ic	k,g	h	h	t	defl	ic	a

 
Absolute Maximum Operating Conditions^¶

CRT	Vh	Ah	Va	Vg	mAa
	6.3	0.3	250	0/15	0.2

Thanks to Frank Philipse for supplying the above PDF datasheet