The VT25 transmitting triode has a large four pin square base. Also on the envelope is the old stores code of 10E/7312. The VT range were the designations of the UK RAF and the envelope carries the crown and AM letters. AM standing for Air Ministry.
The design is elegant and appears quite delicate as in fact it proved to be in this form. The electrodes can be seen to have been displaced within the domed envelope as the top mica is not supported by the glass walls.
This exhibit has the original single inverted V thoriated tungsten filament and is thus quite early.
Above the AM is a code V1203 for which we need details. The leads emerging from the pinch are encased in glass tubes.
The thin sheet anode with flanges at the centre of the working face and within the two supports for the inverted V filament. The grid extends beyond the anode.
