The BSA Standard G225 is a general purpose directly heated dull emitter triode.
The etched lettering within a diamond border.
The electrodes are mounted vertically and the strut on the left is topped by the filament tension spring.
The control grid is wound on a wire support that is held at the base and formed into a semi-circle at the top,
The filament is a single inverted V. The anode is left bright in this low power valve and is oval in cross section. The barium gettering produces the mirror that coats the inner surface of the glass for have of the circumference. The base cap clearly carries the Stand and Telephones and Cables name.
An enhanced view of the filament, grid and anode.
The anode is supported by a single rod, seen here on the left.
The balloon envelope is 47 mm in diameter and, excluding the base pins, is 91 mm tall.
Reference: 1043. Type G225 was first introduced in 1926. See also1926 adverts.
