The 23Z9 is a Compactron double triode pentode television valve. It is designed for 140 Volt HT and a series heater chain of 450 mA.
The pentode is designed for frame output with the triodes aimed at frame oscillator and sync clipper stages in colour TV sets. The triodes are different, a medium-μ one and a high-μ designated as triode section one.
End view of both triodes.
The pentode is a beam tetrode and the envelope carries the Silvertone name and Made in USA.
The dome with the Type designation. The pentode is at the top with the triodes at right angles to the pentode seen below.
The wide glass tube envelope is 28 mm in diameter, and excluding the B12C base pins is 50 mm tall.
Reference: Datasheet. Type 23Z9 was first introduced in 1967.