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.
On the picture it can be seen that the triode is a completely separate electrode structure with an electrostatic screen between it and the power valve electrodes.
Here the bright separating screen can be clearly seen to the right of the small triode.
Face view of the triode section showing the copper grid supports.
The pentode section: visible is one of the two heat radiating tabs on the tops of the screen grid supports. There is also a tab between the control grid supports that runs at right angles to the screen grid tabs.
The thin glass tube envelope is 22 mm in diameter and excluding the B9A pins is 69 mm tall.
References: Data-sheet & 3002. Type PCL805 was first introduced in 1968. See also1968 adverts.
