The Type 46 is an American 'dual grid' audio amplifier. The data-sheet offers a fascinating insight to the complex uses of this valve. Including service as a class B amplifier (with both grids tied together) as a class A amplifier with the outer grid connected to the anode.
The anode is high-up in the envelope with a long pinch and stem below. On the base cap has been scratched the date 28/5/37.
A closer view. The grids appear to have the same winding pitch. The bright rods in the foreground support the filament tension springs.
Here the filaments can be seen as oxide coated ribbons held in the hooks of the tension springs.
The classic envelope is 51 mm in diameter, and excluding the UX5 base pins is 116 mm tall.
References: Data-sheet & 1043. Type 46 was first introduced in 1933. See also1933 adverts.
