The UV201A, introduced in October 1922, has a thoriated tungsten filament and replaced the UV201. It was designed for for both detection and amplification.
By the end of 1922 RCA held exclusive patents as the companies forming RCA transferred their patents. In 1923 it was the most widely sold valve in the USA.
The valve is branded as RCA by the paper sticker but at the time RCA was not making valves.
The location pip on the base cap for the bayonet UV base. The licence terms are referenced on the base cap.
The actual manufacturer was General Electric and the logo is etched into the glass.
The GE logo processed from a microscope image.
The gettering covers almost all of the envelope but a small gap allowed this image of the vertical electrode assembly.
The balloon envelope is 44 mm in diameter and, excluding the UV base pins, is 100 mm tall.
References: 1047 & Joe Gruber. Type UV201A was first introduced in 1922. See also1922 adverts.
