The A11B from Ever Ready is the Mullard IW4-350 rebranded as per the terms of the contract between the companies.
This is an indirectly-heated 4V AC HT rectifier essentially equivalent to the MU12 and UU4.
The balloon envelope suggests that this exhibit was made close to the introduction date of 1935. Later examples mounted the rectifier in the classic or shouldered envelope.
The long pinch stem and the support for the electrodes is provided only by the pinch.
This full wave rectifier features indirectly heated cathodes that are tied to one side of the heater.
Thanks to Mark Mallison for sending the images.
The balloon envelope is mm in diameter and, excluding the B4 base pins, is mm tall.
References: Data-sheet, Private communication & 1043. Type A11B was first introduced in 1935. See also1935 adverts.
