6.3 V indirectly heated cathode, manufactured by Hygrade Sylvania Corporation, Emporium, PA, USA, circa 1950.

The 7A8 is an octode frequency changer designed for use in airborne and other receivers subject to shock and vibration. It has similar characteristics to the 6D8 but the addition of a suppressor grid gives a higher plate resistance, particularly at low operating voltage.

The Loctal base fitted to this valve has a detent on the locating spigot which prevents the valve from coming out of its socket when subjected to vibration such as that encountered in aircraft equipment.

Physical Description

Tubular glass bulb on loctal base.

More Information