The 6DR7 double triode consists of a TV frame oscillator as unit 1 and a frame output amplifier as unit two. This American valve was designed for their 525 line 30 Hz frame system.
Also with the same characteristics but different heater values were the: 10DR7 9.7V @ 0.6A, 13DR7 13V @ 0.45A and 19DR7 18.9V @ 0.3A. All designed for series heater chain use.
The oscillator section is on the left with the power triode on the right. The latter has a grid heat sink fin.
The RCA logo on the amplifier side of the valve.
The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins is 59 mm tall.
Reference: Data-sheet. Type 6DR7 was first introduced in 1959. See also1959 adverts.