SDR770 diversity receiver uses the familiar Micron led layout to indicate signal strength, receiver battery condition and transmitter low battery. Each unit can be powered externally or internally by a 9V PP3 type battery which fits into a very well engineered metal, slide-in battery tray. The transmitter runs for about 6 hours and the receiver for about 4. System frequency response is 80 to 20,000Hz. with a fixed LF cut of -5dB at 50Hz. with a switched additional cut of -6dB at 60Hz