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822-0299-020 – Collins Aerospace ADF-900 Automatic Direction Finder (ADF) Receiver
Available now on the Airparts.aero Marketplace.
The 822-0299-020 is a high-reliability, TSO-certified Automatic Direction Finder (ADF) receiver belonging to the Collins Aerospace Pro Line 4 and Pro Line 21 avionics families. This unit is a core component of an aircraft’s navigation suite, responsible for receiving and processing Low Frequency (LF) and Medium Frequency (MF) signals from Ground-Based Non-Directional Beacons (NDBs) and AM broadcast stations. The ADF-900 translates these signals into relative bearing data, which is then displayed on the pilot's Electronic Flight Instrument System (EFIS) or Radio Magnetic Indicator (RMI).
Engineered for the demanding environment of turbine-class business jets and regional airliners, the -020 variant is a digital, ARINC 429 compatible receiver. It features advanced digital signal processing (DSP) to filter out atmospheric noise and "night effect" interference, providing stable bearing pointers even in adverse weather conditions.
Key Features
Digital ARINC 429 Interface: Seamlessly integrates with modern Integrated Avionics Processing Systems (IAPS), allowing for frequency tuning via the Radio Management Unit (RMU) or Flight Management System (FMS).
Advanced Noise Suppression: Utilizes digital filtering to minimize the "needle hunting" associated with lightning discharges and static interference, a common issue in legacy analog ADF systems.
Broad Frequency Coverage: Receives signals across the standard $190.0\text{ kHz}$ to $1799.5\text{ kHz}$ range, supporting both navigation beacons and maritime signals.
Built-In Test Equipment (BITE): Continuously monitors internal hardware health and antenna link integrity, reporting status codes to the aircraft’s centralized maintenance computer for rapid troubleshooting.
Solid-State Reliability: Housed in a standard 2MCU (Modular Component Unit) rack-mount chassis, designed for high-vibration resistance and efficient heat dissipation.
Technical Specifications
Part Number: 822-0299-020
Manufacturer: Collins Aerospace (Rockwell Collins)
Component Type: ADF-900 Receiver
Frequency Range: $190.0$ to $1799.5\text{ kHz}$
Digital Interface: ARINC 429 (High/Low Speed)
Form Factor: 2MCU Rack Mount
Operating Voltage: 28V DC
Weight: Approx. 6.0 lbs (2.72 kg)
Certification: TSO-C41c (Airborne ADF Equipment)
Aircraft Compatibility
Bombardier Series: Challenger 604, 605, and Global Express (Pro Line 4/21).
Cessna Citation Series: Citation CJ2, CJ3, and Sovereign.
Beechcraft/Hawker: King Air 350 and Hawker 800XP/900XP.
Falcon Series: Dassault Falcon 50EX and 2000.
Note: The 822-0299-020 is the standardized digital ADF receiver for most Pro Line equipped cockpits. Always verify the "Mod Status" against your Aircraft Maintenance Manual (AMM) Section 34-50.
Applications
The 822-0299-020 is utilized for Secondary Navigation and Point-to-Point Tracking. Its primary roles include:
NDB Approaches: Providing the primary bearing data required to fly published non-directional beacon instrument approaches.
Oceanic/Remote Navigation: Serving as a reliable backup in regions where VOR/DME or GPS coverage may be limited.
Aural Monitoring: Allowing the crew to identify stations via Morse code or monitor AM weather broadcasts.
Why Choose 822-0299-020?
Choosing the genuine Collins 822-0299-020 ensures System-Wide Synchronicity. In a Pro Line 21 cockpit, the ADF receiver must maintain a precise "handshake" with the Tuning Units and the Display Processors. Non-OEM or improperly overhauled units can suffer from "Digital Latency," where the ADF needle on the EFIS lags behind the aircraft's actual heading during a turn. The -020 variant is calibrated for specific Sensitivity and Selectivity standards, ensuring it can lock onto distant "fringe" NDBs that lower-quality receivers would lose in the background noise.
The 822-0299-020 operates on the principle of Phase-Coherent Loop and Sense Processing. To determine a bearing, the unit compares the signal from a directional Loop Antenna with an omnidirectional Sense Antenna. The physics of the Cardioid Pattern are processed digitally within the ADF-900 to resolve the "180-degree ambiguity" inherent in radio loops. By utilizing high-speed ARINC 429 Label 162 (ADF Bearing), the receiver provides updates to the EFIS at a rate that ensures smooth needle movement, even during high-rate-of-turn maneuvers in the holding pattern.
Note: This is a flight-critical navigation unit. Installation must be performed by an FAA-certified Part 145 repair station. Prior to installation, the ADF antenna (e.g., ANT-462) and its mounting surface must be inspected for proper electrical bonding ($< 2.5\text{ milliohms}$) to ensure signal clarity. A "Ground Bearing Check" and "Quadrantal Error Test" are recommended post-installation to verify accuracy.
