RECEIVING SET RADIO AN/MRR-4B
Year 1963

Receiving Set, Radio AN/MRR-4B is an air or vehicular-transportable assemblage of high-frequency (hf) radio receivers and associated equipment which can be arranged to provide facilities for reception of voice-frequency (vf), continuous-wave (mcw), and frequency-shift-keyed (fsk) radio teletypewriter signals from 15 kilocycles (kc) to 32 megacycles 8 (mc).
The AN/MRR-4B is normally used as the receiving terminal for Radio Transmitting Set AN/MRT-5(*) (TM 11-643); it may also be used for receiving, monitoring, and recording local or remote radio transmission. Equipment is also provided for sending and receiving teletypewriter page copy or perforated tape messages over a filled wire circuit.
Two Receiver Groups OA-4773/MRR-4B and one Receiver Group OA-4774/MRR-4B is provide in the radio receiving shelter; one OA-4773/MRR-4B is provide in the radio teletypewriter shelter. The OA-4774/MRR-4B provides the operator with complete facilities for the visual or audible monitoring as well as the taped recording of all radio signals received by the AN/MRR-4B whip or doublet antennas.
OA-4773/MRR-4B and the OA-4774/MRR-4-B are similar except for the model number and the frequency range of the radio receiver used (a below).The following components, unless otherwise indicated , are part of both the OA-4773/MRR-4B and the OA-4774/MRR-4B.
Receivers Radio R-389/URR (TM 11-855) and R-390A/URR (TM 11-5820-358-10) are both broadband, high-sensitivity, general purpose radio receivers. The R-389/URR is a part of Receiver Group OA-4774/MRR-4B and has a frequency range of 15 kc to 1,500 kc. The R-390A/URR is part of Receiver Group OA-4773/MRR-4B, and is similar to the R-389/URR except for the frequency range 0,5 mc to 32 mc and the additional capability of single-sideband reception.
The Panoramic Adapter BC-1031 (*) (TM 11-446) provides the operator with a visual (cathode-ray tube) display of radio signals that are centered around the frequency to which the associated R-389/URR or R-390A/URR is tuned.
Normally, the BC-1031-(*) displays all radio signals 100 kc above and 100 kc below the tuned frequency of its companion receiver.
When used with the R-389/URR or R-390A/URR , however, only frequencies 5 kc above and 5 kc below the tuned frequency are capable of being displayed on the calibrated scale of the cathode-ray tube.
Tape Recorder PT-63-AHX and Recording Amplifier PT-63-JX comprise a complete two speed tape-recording and playback system that provides facilities for recording (on magnetic tape) the output from an associated R-389/URR or R-390A/URR.
Facilities are also provided for the instantaneus aural monitoring of taped material after it has passed under the recording head. A self-contained volume unit (vu) meter provides the operato with a visual means of monitoring the rcording level.

DEPARTMENT OF THE ARMY TECHNICAL MANUAL TM 11-5820-471-12