The 6AD10 Compactron is an amplifier pentode designed as an FM detector in television receivers, and an audio output beam tetrode in a single envelope. This one valve provides the audio stages of a TV receiver.
The larger section on the left is the output stage and can deliver 4.2 Watts. On the right is the smaller pentode. The suppressor grid support can be seen through the side of the anode.
The beam tetrode.
The pentode: the suppressor grid is close wound, indicating a short grid base and thus suitable as a control electrode. See also17BF11 another dual control pentode for FM demodulation.
The dome carries the etched Type designation.
The wide glass tube envelope is 29 mm in diameter, and excluding the B12C base pins is 54 mm tall.
References: Datasheet, 1040 & 1043. Type 6AD10 was first introduced in 1966.