The UV201 was originally made by General Electric as the UV201, the Westinghouse version was slightly different electrically. Both makers were making for the newly formed RCA.
The first valves that RCA is selling in 1920 are the soft detector UV200 (argon gas) and the hard UV201 Amplifier. In 1922 General Electric introduces the dull emitter UV201A (thoriated tungsten filament).
The inside of the envelope has a hint of colour - possibly some gettering. The soft UV200 has a clear glass envelope.
The bright anode box with rounded ends. The filament tension spring at the top holds the loop of the single inverted V filament. The grid has an open pitch.
The brass base skirt with printed lettering. The locating pin on the left was required as the UV base was of the twist and lock bayonet type.
The original box. Westinghouse was a partner in the formation of RCA. The box features the original RCA brand logo and is thus from the early 1920s and quite rare - especially in this condition. The Westinghouse logo at the base of the box is the same as the white image on the envelope.
Thanks to Joe Gruber for sending the images.
The envelope is mm in diameter and, excluding the base pins, is mm tall.
References: 1047Joe Gruber. Type UV201 was first introduced in 1920.