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.
The bright anode with spot welds holding the nickel plates to the side supports.
The insulated heater is twisted together to cancel the external magnetic field.
The top mica showing the heat radiating fins on top of the grid supports.
The classic envelope is 38 mm in maximum diameter and excluding the IO base pins the valve is 88 mm long.
References: Data-sheet, 1040 & 1043. Type 6J5G was first introduced in 1936. See also1936 adverts.
