Sensibly equivalent¶ to:
The D77 is the Marconi equivalent of the Mullard EB91, and consists of two separate signal diodes in the envelope.
The QD77 is the special quality version of this valve type.
The diodes were designed for vision and sound detection in television receivers. Additionally they are recommended for limiting and DC restoration.
The thin glass tube envelope is 17 mm in diameter and, excluding the B7G base pins, is 44 mm tall.
References: Data-sheet & 1040.
Absolute Maximum Operating Conditions¶
Updated January 05, 2013. shape:thin.glass.tube construction:all.glass type:double.diode age:1950.1960 base:b7g heater:6.3v pins:7 pin:1.k pin:2.a pin:3.h pin:4.h pin:5.k pin:6.s pin:7.a