The 1Q5GT is a battery audio output valve capable of providing around one quarter of a Watt of output. It was designed for use with a single dry call as filament supply and 90 Volts HT.
The valve is branded Philips and Made in USA. The lozenge on the glass looks very much like an RCA product. This was clearly made during WWII.
The side view of the box anode.
The anode face view.
The filament is a pair of oxide coated strands. The grids can be seen through the top mica sheet.
The filament tension springs.
The wide glass tube envelope is 29 mm in diameter, and excluding the IO base pins is 60 mm tall.
Reference: Data-sheet. Type 1Q5GT was first introduced in 1940. See also1940 adverts.
