APO – a function of a portable radio designed to conserve battery charge. Automatic power off helps extend battery life by automatically switching the radio off after a preset period of time if no button has been pressed. If, after a specified time interval, the user has not pressed any front panel buttons, rotated the DIAL knob, pressed the PTT transmit button, and if the radio is not operating in scanning or monitoring mode, the unit will power down.
Some radio models allow setting the automatic power-off time within a range from 0.5 to 12 hours. This function minimizes the risk of premature battery depletion during prolonged non-use of the device, in case you forget to switch off the radio’s power.
In addition, some radio models implement audible and visual alerts warning the user of an impending APO timer shutdown. If, after the preset period, the radio has remained inactive, an audible signal will sound, after which the radio will switch off. For example, in the Vertex Standard VZ-9 radio, one minute before shutdown, the APO icon begins to flash on the display and a warning tone is emitted.