The MFJ-1707B is RF sensed TR Antenna switch designed to be used with a transceiver and two antennas. This allows you to use a separate receive antenna and transmit antenna allowing the versatility of specialized receive antennas such as receiving loops or low noise receive antennas and general-purpose transmitting antennas. The MFJ-1707B has a Stripline PCB reducing the SWR up through 450MHz and improving isolation for better receiver protection. Features RF Sensing for radios that do not have a keying output when transmitting. Good isolation between transmit and receive ports. Good SWR characteristics up to 450MHz. Control Line input for radios that have a key line output. An AUX output that can be set to ground to mute or open to mute to key other devices. Power-off bypass setting the transmitter to the antenna Adjustable receive delay 50ms to 4 seconds Connections and Controls REC Connection for the receiver. ANT Connection to the antenna. XMTR Connection to the transmitter. AUX Connection to the receiver mute terminal. CTRL Connection to the transmitter PTT or KEY line. +12V Power Connector DELAY Receive delay adjustment. RX ANT XCVR TX A.