The PL36 was designed as a line timebase output valve for television receivers. In 1962 it was replaced by the PL500.
The design dates to the 1950s, when sets were black and white and screen sizes of 14 - 17 inches diagonal were common. The PL36 was designed for driving the line deflection on 90° deflection angle tubes with a final EHT of 16 kV.
From a Mullard Press release in February 1956: The Mullard PL36 is an output pentode primarily designed for the line timebases of television receivers using picture tubes with a deflection angle of 90°, and 16 kV EHT. The new valve is octal based, and has a 25 V, 0.3 A heater, suitable for series operation.
The maximum positive peak voltage on the anode is 7 kV and the screen dissipation is up to 5 W.
Side view of the anode. The bright strips at the top support the getter holder. The side box adds area for heat dissipation.
The beam plates are visible through the anode notch on the right. The control grid supports are topped by radiating fins.
Here the shape of the control grid heat radiators can be seen as well as the copper grid supports. The rectangular cathode tube has a single heater loop within. The heater can be seen to be an insulated coil.
The wide glass tube envelope is 28 mm in diameter and, excluding the IO base pins, is 95 mm tall.
References: Data-sheet & 1040. Type PL36 was first introduced in 1955. See also1955 adverts.
