The 6L6G it is a larger more powerful audio beam tetrode than the 6V6 receiver type. This was used for audio amplifiers and modulators for small Amplitude Modulated transmitters.
The RCA logo.
This exhibit is unusual in having added to the envelope the printed lettering showing that the valve was distributed by the Edison Swan Electric company.
The top mica showing the heat-sink fin attached to the copper control grid supports, the flat cathode and carbonised anode. The beam forming plates can be seen as the bright plates within the anode.
The classic envelope is 51 mm in diameter and, excluding the IO base pins, is 116 mm tall.
References: Data-sheet, 1040 & 1043. Type 6L6G was first introduced in 1936. See also1936 adverts.
