What is the function of component 2 in figure T-1?

In standard amateur radio schematic diagrams, Component 2 in Figure T-1 represents a simple single-pole single-throw (SPST) switch. The primary purpose of a switch in any electrical circuit is to open or close the circuit path, which controls whether current can flow. Other distractors describe entirely different components. A component that gives off light is a lamp or LED, one that supplies energy is a battery or power supply, and one that converts electrical energy into radio waves is an antenna.