Cross Country Wireless now have the first production models of their HF/VHF/UHF Multicoupler available for sale.
This is a multicoupler or antenna distribution amplifier that can share a single antenna between up to five receivers. It also provides lightning surge and over-power protection on the antenna port.
This product has been under development for over a year and one of the spin-offs from the work was the revised RF front end for the SDR-4+ receiver.
The multicoupler has a very wide bandwidth (1 to 400 MHz -3dB) and a very high output IP3 figure of 40 dBm.
The specification for reverse isolation and receiver to receiver isolation is also very good (typically better than 50 dB).
More information - http://www.crosscountrywireless.net/multicoupler.htm