SWINGING.--See Fading.
SWITCH, AERIAL.--A switch used to change over from the sending to the receiving set, and the other way about, and connect them with the aerial.
SWITCH, LIGHTNING.--The switch that connects the aerial with the outside ground when the apparatus is not in use.
SYMBOLS, APPARATUS.--Also called conventional symbols. These are diagrammatic lines representing various parts of apparatus so that when a wiring diagram of a transmitter or a receptor is to be made it is only necessary to connect them together. They are easy to make and easy to read. See Page 307 [Appendix: Symbols Used for Apparatus].
SYNCHRONOUS GAP.--See Gap, Synchronous.
TELEPHONY, LINE RADIO.--See Wired Wireless.
THERMAL AMMETER.--See Ammeter, Hot Wire.
THREE ELECTRODE VACUUM TUBE.--See Vacuum Tube, Three Electrode.
TIKKER.--A slipping contact device that breaks up the sustained oscillations at the receiving end into groups so that the signals can be heard in the head phones. The device usually consists of a fine steel or gold wire slipping in the smooth groove of a rotating brass wheel.
TRANSFORMER.--A primary and a secondary coil for stepping up or down a primary alternating or oscillating current.