The EF5 is a variable μ amplifier pentode.
The variable μ amplifier pentode would be used in the AGC controlled stages of superhet receivers, IF and for HF receivers also RF amplifiers.
Our exhibit is unused, and has the distinctive red painted Mullard external metalisation screening. We also have a version of the EF5 with gold metalisation and an IO base.
The classic envelope is 30 mm in diameter and, excluding the Ct8 base pins, is 82 mm tall.
References: Datasheet & 1043. Type EF5 was first introduced in 1938.
Absolute Maximum Operating Conditions¶
Updated January 29, 2013. shape:classic construction:pinch type:pentode age:1930.1940 base:ct8 heater:6.3v pins:8 pin:1.m pin:2.h pin:3.h pin:4.k pin:5.g3 pin:6.- pin:7.g2 pin:8.a pin:tc.g1