The 11D3 is a double diode triode receiver valve designed for universal sets, that is with a series heater chain and no mains transformer and dates to 1934 when DC mains still existed.
It is interesting that this should have been the valve featured on the playing cards that Brimar issued as advertising material. It seems branded playing cards were popular in the mid 1930's.
The electrodes in side view the triode anode is at the top and the pair of signal diodes have half box anodes below the middle mica.
This is the only time this Brimar logo has been seen.
The common cathode is oxide coated only in the working areas. The triode can be seen to have a cylindrical anode and the grid is close wound. The grid connection passing to the top cap can be seen at the top of the image.
The classic envelope is 39 mm in diameter, and excluding the B7 base pins is 100 mm tall.
References: Data-sheet, 1040 & 1043. Type 11D3 was first introduced in 1934. See also1934 adverts.
