The Type designation code on this 6J5G is only SC122A but it is precisely a 6J5 triode.
The 6J5G is a single medium μ triode is housed within a glass envelope. This is a classic triode design with the popular audio double triode the 6SN7 being a pair of 6J5s in a single envelope.
We also have the Brimar version 6J5G, the Cossor version 6J5G, the later glass tubular version 6J5GT and the American metal version 6J5 within the museum.
The Raytheon name and Made in USA.
The glass has distorted the image but apart from the ribbed and stitched anode the feature present is a radiating fin on the top of the control grid supports. The metal pieces around the circumference of the top mica are retaining springs to grip the inside of the glass.
Top view: the cathode is a round tube.
The classic envelope is 38 mm in maximum diameter and excluding the IO base pins the valve is 84 mm long.
References: Data-sheet, 1040 & 1043. Type 6J5G was first introduced in 1936. See also1936 adverts.
