The 51RV-4B is a solid-state, airborne navigation unit that combines the VOR, localizer, and glideslope functions. The dual-conversion 200-channel VOR/LOC (108 to 118 mHz with 50-kHz channel spacing) and 40-channel glideslope (329 to 335 mHz with 150-kHz channel spacing) receivers are remotely controlled by 2-out-of-5 binary or by serial information transmitted in ternary broadcast form. The 51RV-4B has the capability of dual-instrumentation circuits with internal comparison and level monitoring; other options available are self-test functions, digital bearing output, added filtering of the basic bearing information, serial tuning, RMI servo amplifier, and heads up display driver capability. The 51RV-4B VOR/ILS Navigation Receiver receives VOR, localizer, and glideslope signals and provides outputs to operate deviation, flag, and to-from indicators; and to operate the VOR pointer of an RMI (radio magnetic indicator). The 51RV-4B operating frequencies are 108.00 to 117.90 mHz for VOR/LOC and 329.15 to 335.00 mHz for glideslope. When tuned to a VOR frequency, the 51RV-4B operates with an external course indicator that provides a 400-Hz electrically zeroed course resolver. Outputs from the 51RV-4B operate VOR deviation and to-from indicators, a VOR warning flag, a relative bearing indicator, and supply an aural output. The 51RV-4B is capable of being tuned 2-out-of-5 binary control or serial tune input. A digital VOR bearing word output provides for operations of digital instruments and systems. The 51RV-4B adds expanded monitoring in the VOR/ILS functions. The -201 status of the 51RV-4B provides the heads up display capability.

The 51RV-4B is housed in an ARINC 1/2-ATR short case with mounting facilities per ARINC 404 and 404A. Electrical connections are made through a dual DPX connector on the rear of the chassis. The mechanical construction of the 51RV-4B is such that all electrical components are accessible with the dust cover removed. The height is 7.839 inches, width 5.050 inches, length 16.348 in including handle projection, and a max weight of 12.5 pounds.