The MFJ-1040C lets you copy weak signals.  It rejects out-of-band signals and images.  It covers 1.8 - 54 MHz with up to 20 dB gain.  It has gain control.  It uses a cascode FET/bipolar transistor for low noise, high gain.  20 dB attenuator.   Connect 2 antennas and 2 receivers.  It uses SO-239 connectors.  Automatic bypass with transmitting to 125 Watts.  Jack for push-to-talk.  9-18 VDC or use the MFJ-1312D power adapter.