What is the power source for the Al101?
A 9-volt alkaline battery is used to power the Al101, and the UT2000 Transmitter as well. A single battery can power the Al101 for more than 45 hours of continuous use. The meter output is also used as a battery power indicator by turning the output switch in the down position where only the headphones are pictured. The battery will need to be replaced if the needle drops below the “5-10” mark on the meter. The old battery can be used in the UT2000 for an additional 30 continuous hours. A single, fresh battery can power the UT2000 for up to 300 hours of continuous use.