The 6AD7G is an octal-base triode-pentode designed primarily for phase inverter and push-pull audio power output service in vintage radio chassis and high-fidelity audio equipment. Housed in a classic shoulder-type (ST-16) glass envelope, its pentode section is electrically identical to a 6F6G power output tube, while the triode section provides the phase inversion signal required to drive a second 6F6G in a push-pull output stage. Operating on a 6.3V/0.85A heater, it was specified in pre-war and early post-war console receivers produced by manufacturers such as Zenith, Philco, RCA Victor, and Crosley. Available in NOS and tested used conditions.