VHF radios have a dedicated "1/25", "1W/25W" or "Lo/Hi" button that toggles between Full (25 W) and Low (1 W) transmitter power. When either VHF CH 15 or 17 are selected (guard channels either side of VHF CH 16), Low transmitter power is automatically selected, in which case the dedicated button will have no effect. Low transmitter power shortens the transmission range and also preserves battery capacity.

Practise on the VHF radio simulator

A single press of the 1/25 key toggles between Full (25 watt) and Low (1 watts) transmitter power.