The 16LU8A is a Compactron triode pentode designed for television receivers. The medium-mu triode was designated for use as a frame oscillator and the pentode as the vertical deflection amplifier. The 16LU8A was designed for series heater chains and the otherwise electrically identical 6LU8 was intended for parallel heater systems.
Although referred to as a triode pentode the construction is as a triode beam tetrode.
The beam tetrode section. The anode dissipation is up to 14 Watts.
Seen end on the centre sheet is a screen connected above the top mica to the beam forming plates and thus to the cathode.
The dome carries the Type designation. In the foreground can be seen the connection between the central screen and the beam plates. Both sections have copper support rods for the control grid and radiating fins.
The metallic looking sheet on top of the top mica is another piece of mica. The stitching of the triode anode can just be seen.
The envelope is 38 mm in diameter, and excluding the B12C base pins is 70 mm tall.
Reference: Datasheet. Type 16LU8A was first introduced in 1968.