A new valve in the Tungsram range is the APP4C. It is a pentode with a heater rated for 4 Volts at 1.9 amperes, and it is intended for operation with anode and screen supplies of 250 Volts with which a grid bias of -6 Volts is required. The anode current is 36 mA., and the screen current 4 mA., and an output of 3.0 Watts is claimed. An unusual feature is that the suppressor grid is brought out to a pin on the base, and it is recommended that a bias of -6 volts be applied to this grid. It is claimed that this renders the valve much less prone to parasitic oscillation, and that the usual grid and anode stopping resistances can consequently be omitted.
The valve is priced at 14s. 9d., and a Universal counterpart, the PP36, with a heater rated for 35 Volts at 0.2 ampere, is available. The makers are Tungsram Electric Lamp Works, Ltd., 72, Oxford Street, London, W1.