an electric battery for heating the filament or cathode heater of an electron tube.
Origin of A battery
First recorded in 1920–25
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020
Examples from the Web for a battery
We shall call the battery which heats the filament the “filament battery” or sometimes the “A-battery.”
To do so connect the grid as in Fig. 115 to the positive terminal of the A-battery.