The PCC84 double triode shows how valves developed to meet the needs of the planned VHF television (Band III) transmission that opened in the UK in 1955. The design was superseded by the PCC89.
The PCC84 and PCF80 both featured in set-top converters for the new ITV television Band III channels that commenced broadcasting in 1955. The transmissions were on around 170 MHz and much higher in frequency than the BBC Band I signals at around 50 MHz.
The PCC84 was specifically designed for cascode operation. The normal configuration was for triode one to be operated as a grounded cathode stage directly coupled to triode two. Triode two was connected as a grounded grid stage.
The bright electrostatic screen sits between the two triodes. The heater wire is in fact an insulated coil.
looking along the grid axis with both triodes oriented in the same way.
The thin glass tube envelope is 22 mm in diameter and excluding the B9A base pins is 47 mm tall.
References: Data-sheet & 1040. Type PCC84 was first introduced in 1953. See also1953 adverts.
