The 7734 is a special quality version of the 6GE8 triode pentode. The main design purpose is as a voltage regulator with the pentode as the difference amplifier and the triode as the series pass device. Series regulators place heavy demands on the cathode due to the high constant current and this valve has a powerful heater for the triode as well as a large cathode. The triode control grid has radiating fins above the copper support rods.
The makers identification. The triode is on the left and the small pentode is placed at 90 degrees to it and is located on the right of the image.
On the extreme left is the pentode anode as a vertical plate. After the gap is the main electrode assembly of the single sided pentode (actually a beam tetrode). The beam plate is the dark rectangle with the wire grids inside, running front to back. The triode is on the right with the large cathode clearly visible face-on.
The pentode grid supports are at the top of the image. The pentode anode has moulded ridges for structural support.
The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins is 59 mm tall.
Reference: Data-sheet. Type 7734 was first introduced in 1960.