That looks like the same model a friend of mine had in the very late 70's. I know my faithful 1980 Panasonic is not electronic so there's a good chance your Radarange is one of the first, if not the first. I came across a couple of owners manuals for the Radarange in a thrift store recently but they were for older models with knobs instead of touchpads and dated back to the late 60's.