Power ON/OFF connects the VHF radio to its power supply so until it is switched on the radio is useless. For some equipments there is a dedicated push button control but for more portable equipments it is combined with the volume control.
Volume makes the level of sound higher or lower from the loudspeaker or handset earphone.
Practice on VHF radio simulatorSwitch the VHF radio ON by turning the VOLUME knob clockwise until the display illuminates. To increase the volume, turn the knob further clockwise. Turn the knob fully counterclockwise to switch OFF.
Switching the VHF radio ON