This works by turning the receiver on for a short period of time about once a second. If a signal is present the receiver will stay on. If not, it will wait another second before turning on again. Because of this feature it is very important that you wait at least one second before speaking after you depress the transmit switch. Otherwise the other person's receiver will cut off the first word of your transmission.
Some radios have a switch that selects high or low transmitter power.
Always use the low power setting as much as possible to conserve your battery. Carrying an extra battery on a search mission is an absolute requirement. Rechargeable batteries lose capacity unless they are constantly trickle-charged. Because of this you may not know the capacity of a battery unless it has just been charged. Alkaline batteries are the best to use as backup.