The 316A is a UHF power output valve triode, made by Western Electric in the USA. It is a wonderful doorknob shape, and is a famous type of valve in that it was used for the first successful radar transmitter to be operated whilst airborne. In this application it was operated in pulse mode and the individual pulses were of a few hundred watts.
The maximum grid current for its native Class C mode of operation is 12 mA.
From top to bottom: Filament tension spring, filament strand, grid cage and anode.
The getter holder with some un-fired material still in place. Behind is the sweeping arm of the filament spring.
The lettering is clear as is the envelope that shows no sign of the getter having been successfully fired.
The balloon envelope is 60 mm in diameter and, excluding the special base pins, is 62 mm tall.