It is a LNB with feedhorn for circular KU band. The LNB was manufactured by Japan Radio and probably still works as they were bullet proof. The first two letters indicated the band that it was set to receive is 11.700 - 12.200 Ghz. The age would suggest only right hand polarity and likely the LO frequency of 10.678 (which was unusual for North America). The conical design of the scalar suggests that it was previously mounted on an offset design, high FD ratio reflector (.6 or .7).
Not many KU satellites received in North America use circular KU band signals in the 11.7 to 12.2GHz range, so it was likely receiving data or entertainment programming from an international satellite.
