The 6BJ6A is a line timebase valve from America, and is thus designed for 525 lines and 60 Hz frame timebase. The anode dissipation is quoted as 17.5 Watts. This suggests a use in a small screen sized colour receiver or a monochrome set. Larger colour sets used valves with a dissipation of up to 25 Watts.
The carbonised anode has broad side wings as extra dissipation surfaces.
The base view showing the wide cathode tube. A large cathode and consequent significant heating power is required to cope with peak current pulses of up to 550 mA.
The wide glass tube envelope is 38 mm in diameter, and excluding the B9D base pins is 79 mm tall.
References: Datasheet. Type 6JB6A was first introduced in 1964.