Are you looking for radar mosaics? I normally use this link for downloading radar data though they're not mosaics: http://motherlode.ucar.edu:8080/thredds/idd/radars.html
N0R is the legacy reflectivity product that is limited to 124 miles from the radar site. NOZ goes out to 248 miles, but is lower resolution. Iowa State offers single site images in the newer 8-bit/256 color format (which by default is full range).http://mesonet.agron.iastate.edu/GIS/ridge.phtmlThe product you'll want is called N0Q.I checked the Ridge 2 directories on the NWS website, but the single site ones are empty.Then there's mosaic images. http://radar.weather.gov/ridge/Conus/RadarImg/http://mesonet.agron.iastate.edu/docs/nexrad_composites/