The 30C18 is a purpose designed oscillator and mixer for frequency changer use in VHF television receivers and directly equal to the PCF805 as can be seen from the envelope.
The perforated screen over the pentode gives glimpses of the grids within. This indicates that the anode is not continuous but s pair of plates either side of the cathode.
The triode and pentode control grids have copper supports.
Face view of the small triode.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 46 mm tall.
References: Data-sheet & 1040. Type 30C18 was first introduced in 1962. See also1962 adverts.