The RAMI AV-590 allows two communications radios to share the same antenna.  In the nominal, non-switched mode the AV-590 splits the signal from the antenna evenly between two comm radio receivers.   When the control voltage is activated by the microphone PTT, the AV-590 switches the antenna to the corresponding radio transmitter and isolates the other receiver. Product Specifications: Model    AV-590 Application    Comm Antenna Splitter Frequency    118-136 MHz Impedance    50 Ohms Nominal VSWR    1.2:1 Max DC Voltage    12-15 VDC @ 60 mA Max Insertion Loss    < .6 dB above 3.0 dB Isolation    >30 dB Connector    “BNC” Female RF Power Capacity    25 Watts TX Color    Black