The 4300A is an audio power triode from STC. The design is from the Americam parent company and the American Type designation is 300A.
The side flanges on the anode are present to assist with thermal management.
Looking along the grid axis.
The top mica with filament strands and tension springs.
Looking down on the top mica showing the support rods with the filament tension springs attached.
The pinch and lower mica. The stitching of the anode halves can be seen as can the base of the filaments. The control grid is just visible on the right.
The classic envelope is 60 mm in diameter and, excluding the UX4 base pins, is 136 mm tall.
Reference: Data-sheet. Type 4300A was first introduced in 1938. See also1938 adverts.
