The EB91 is a double signal diode. These diodes were designed for vision and sound detection. Additionally they are recommended for limiting and DC restoration. Each section is internally screened.

The two valves are separate almost flat structures separated by a bright plate screen. This clearly shows the signal usage, where it is important to keep RF isolation. The wire at the top of the picture is the getter support.

The thin glass tube envelope is 18 mm in diameter and, excluding the B7G base pins, is 47 mm tall.

References: Datasheet & ¹⁰⁴⁰. Type EB91 was first introduced^¶ in 1949.

 
Pin Connections

B7G	1	2	3	4	5	6	7
	k(1)	a(2)	h	h	k(2)	s	a(1)

 
Absolute Maximum Operating Conditions^¶

Diode	Vh	Ah	Va	mAa
	6.3	0.3	150	9

Thanks to Frank Philipse for supplying the above PDF datasheet

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