RDR 1400C SAR and Weather Radar

The RDR 1400C, also designated AN/APN-239 in the American Joint Electronics Type Designation System (JETDS), is a lightweight digital X-band airborne radar system designed for fixed and rotary-wing aircraft. Manufactured by Telephonics (originally Bendix/King) and used in aircraft like the Sikorsky HH-60G and MH-60G, it operates at 9375 MHz ±5 MHz for Synthetic Aperture Radar (SAR) and weather modes, and 9310 MHz for beacon mode, with a peak power of 10 kW and an instrumented range of 240 nautical miles (444 km). It offers five primary operational modes, including two conventional weather avoidance modes and three air-to-surface detection modes, and can receive signals from both standard 2-pulse and DO-172 6-pulse beacon transponders. Key components include a receiver-transmitter unit, radar control panel, antenna drive, and antenna array, with available flat-plate arrays of 25 cm (10"), 30 cm (12"), or 45 cm (18") diameters, and the DA-1203A antenna drive unit providing pitch/roll stabilization and 60-degree or 120-degree sector scans. The system converts radar data to an ARINC 708 control bus via an ARINC 429 interface, requiring 28 V DC, 115 V AC, and aircraft gyro inputs.

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