Tests Antenna and Radio Tx and RxNo need to call for a radio check when you have this compact, easy to use, unit on-board. Unlike other meters in its class, the ART-3 tests receiver function as well as output power and VSWR (antenna efficiency). It is powered by an internal battery or can be connected to ships 12 VDC with the supplied power cable. Battery level can be checked at the flip of a switch. No serious boater should be without an ART-3. Frequency Range: 155-158 MHz RF Power Scale: 0 to 30 watts Impedance: 50 ohms Accuracy: 10% Connectors: SO-239 Construction: Die-cast aluminum Signal Generator 3 KHz Deviation Tone: 1000 KHz RF Level: -115 dBM (approx.)