The PCL805/85 triode pentode was purpose designed as a domestic television receiver frame output stage. The original design was the PCL85 and was improved to the PCL805. The designation PCL805/85 just indicates the interchangeability rather than another design.
As is common with TV valves it is designed to operate at a relatively low voltage and high current as valve based TV receivers operated without mains transformers. The beam tetrode has a quoted load resistance of 4,000 Ohms.
The literature quotes an audio output rating for the PCL805 but this was not the case for the earlier PCL85. In any case the valve of choice for audio output was the PCL86.
Copper control grid supports and heat radiating fins on the screen grid.
The power valve. No sign of a suppressor grid just two bright tabs of the beam plates.
The Rediffusion logo as seen on the valve.
Rediffusion started as a cable distribution service but developed into running the weekday ITV franchise in the London area and TV rental. In the North of England Granada was the big player.
The station identification used in the 1950s and 1960s.
A large shop front. Valve televisions required much servicing especially colour TV sets. Renting a TV was the norm and such businesses flourished until reliable all transistor Japanese equipment became common and cheaper than earlier generations of sets.
The service van as an additional advert for the company. Valves branded with the company logo advertised the brand and helped reduce pilfering.
The thin glass tube envelope is 20 mm in diameter and excluding the B9A pins is 70 mm tall.
References: Data-sheet & 3002. Type PCL805/85 was first introduced in 1968.