AN/ARA-50 Automatic Direction Finding System

The AN/ARA-50 is an automatic direction-finding (ADF) and range-finding (TACAN) system for homing on UHF signals.

This system, powered by the primary bus, operates within the frequency range of the AN/ARC-34 command radio receiver and is controlled through the function switch on the AN/ARC-34 control panel.

The system automatically indicates the bearing of UHF signals emanating from selected ground stations, UHF radio-equipped airplanes, or other UHF radio-equipped sources, allowing the use of these frequencies for homing and rendezvous.

The AN/ARA-5O system can be used with the AN/ARN-72 TACAN system to automatically indicate range of the UHF signals emanating from a preselected airplane.

When the AN/ARC-34 function switch is turned to ADF, a changeover relay in the system disconnects the AN/ARN-6 radio compass signal that is sent to the radio magnetic indicator, and connects, in its place, a directional signal from the AN/ARA-50 ADF system. Relative bearing is indicated by the No. 1 (ADF bearing) pointer on the indicator. Range indication is shown on the AN/ARN-72 TACAN range indicator.

To facilitate the reception of UHF signals for ADF bearings, a flush-type antenna is installed in the lower surface of the fuselage centerline.

Normal Operation

  1. With the command radio on and warmed up, select a common frequency with the ground station or airplane to be homed on.

  2. Turn the AN/ARC-34 function switch to ADF, and the AN/ARN-72 TACAN function switch to A/A.

  3. The ADF bearing pointer will move in response to the UHF signal to indicate the bearing, and the TACAN range indicator will indicate the range to the ground station or to the airplane.

NOTE: For normal UHF communication, the function switch should be returned to MAIN or BOTH. However, transmission is possible when the switch is at ADF.