The 6R7G double diode triode was designed for radio receiver use. In the classic superhet broadcast receiver such a valve would provide signal and AGC rectification, followed by the first audio amplification.
The 6SR7 has the same rating but is in a single ended metal envelope.
The RCA logo and Radiotron brand. The triode is seen end on.
The conventional construction; the triode at the top with the screening box containing the diode rod anodes below the centre mica.
Here the control grid can be seen above the anode with copper supports and connection to the top cap. The rectangular screening for the diode anode rods can be seen to be connected by a tape to the cathode.
The classic envelope is 38 mm in diameter, and excluding the IO base pins, is 97 mm tall.
References: Data-sheet, 1040 & 1043. Type 6R7G was first introduced in 1936. See also1936 adverts.
