The AWA 976A Hybrid Car Radio

In the beginning, the radios used in cars were nothing more than small domestic valve receivers. They were powered by an assembly of filament (A), high tension (B) and bias (C) batteries, which was rather unwieldy.

In most cases, these radios would have been used only while the vehicle was stationary (and with the engine off), as the ignition noise from vehicles such as the Model-T Ford would have been horrendous. In short, they were hardly a practical proposition and their use would have been restricted to a small percentage enthusiasts.

It soon became obvious to the manufacturers that there was a market for dedicated car radios and suitable sets began to appear during the early 1930s. In fact, it was this development that prompted valve manufacturers to produce valves with 6.3V heaters, to suit the 6V electrical systems used in cars at the time.

The ubiquitous vibrator also made its appearance during the early 1930s and this meant that car radios could now be completely powered from the vehicle’s electrical system. These vibrators were initially half-wave devices but were swiftly replaced by the full-wave types which are familiar to vintage radio enthusiasts.