The PCL83 is a television audio triode output pentode from the era of VHF television in the 1950s. It produces enough output power for an average domestic environment but was designed for frame timebase and frame output.
This standard design was made by several manufacturers. Here the staining inside the glass tells of a hard service life.
The grid winding of both the triode and the pentode can be seen. In RF valves the sections are mounted at right angles.
The discolouration is mainly around the power section as would be expected.
The thin glass tube envelope is 20 mm in diameter and excluding the B9A base pins, is 49 mm tall.
References: Data-sheet & 1040. Type PCL83 was first introduced in 1954. See also1954 adverts.