26 OtherPower SourcesWhen an RTR-500 is used as a Base Unit, power comes from thePC through the USB connection; there is no need for any otherpower source.When an RTR-500 Unit is being used as a Repeater, please prepareone of the following separately.AC Adaptor (T&D Option AD-06A1)or Batteries (Two AA alkaline batteries)AC AdaptorConnection JackEstimating Battery LifeIf the Unit is used as a Repeater for wireless communication five minutesa day, new batteries can be expected to last about six months.- Battery life varies depending upon the type of battery, the battery performance, themeasuring environment and frequency of use.Note- Always use two batteries of the same type.- Make sure that + and - are in the correct direction.- Batteries cannot be charged inside the Unit.- The LED lamp will blink once when usable batteries are installed.- Leaving alkaline batteries in the unit for a long period of time may cause battery leakageand corrosion. When using as a backup source, we recommend that you change thebatteries every few years.