The 6CG7 is a general purpose medium μ double triode. Television receivers were a major user of the 6CG7 but use as an RC coupled amplifier is also discussed in the data-sheet. With a maximum anode dissipation of five Watts this would make a good replacement for the ECC82 in a small audio amplifier. Note that pin 9 is not connected and the 6.3 Volt heater supply connects to pins 4 and 5.
The side view of one anode. The flanges are in the centre of the working face.
The triode sections are 13 mm tall.
The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins is 59 mm tall.
Reference: Datasheet. Type 6CG7 was first introduced in 1956.