GAP, NON-SYNCHRONOUS.--A rotary spark gap run by a separate motor which may be widely different from that of the speed of the alternator.
GAP, QUENCHED.--(1) A spark gap for the impulse production of oscillating currents. (2) This method can be likened to one where a spring is struck a single sharp blow and then continues to set up vibrations.
GAP, ROTARY.--One having fixed and rotating electrodes.
GAP, SYNCHRONOUS.--A rotary spark gap run at the same speed as the alternator which supplies the power transformer. Such a gap usually has as many teeth as there are poles on the generator. Hence one spark occurs per half cycle.
GAS-CONTENT TUBE.--See Vacuum Tube.
GENERATOR TUBE.--A vacuum tube used to set up oscillations. As a matter of fact it does not generate oscillations, but changes the initial low voltage current that flows through it into oscillations. Also called an oscillator tube and a power tube.
GRID BATTERY.--See Battery C.
GRID CHARACTERISTICS.--The various relations that could exist between the voltages and currents of the grid of a vacuum tube, and the values which do exist between them when the tube is in operation. These characteristics are generally shown by curves.
GRID CONDENSER.--See Condenser, Grid.
GRID LEAK.--A high resistance unit connected in the grid lead of both sending and receiving sets. In a sending set it keeps the voltage of the grid at a constant value and so controls the output of the aerial. In a receiving set it controls the current flowing between the plate and filament.