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 has a gold metallisation, that is quite different to the distinctive red Mullard external metallisation on our other EF5. In this exhibit the base is International Octal. Normally Mullard would issue an IO version of the Ct8 series under an Octal type designation.
The classic envelope is 30 mm in diameter, and excluding the IO base pins, is 84 mm tall.
References: Data-sheet & 1043. Type EF5 was first introduced in 1938. See also 1938 adverts.
Absolute Maximum Operating Conditions¶
Updated January 08, 2022.