ARK-9

ARK-9 automatic direction finder in aircraft navigation

The ARK-9 is an aircraft automatic direction finder used for navigation by non-directional radio beacons and broadcast radio stations in the long- and medium-wave bands. The system determines the relative bearing to a selected ground radio station and sends this information to the cockpit course indicator. For aircraft crews, ARK-9 is a practical navigation aid: it helps fly toward or away from a beacon, monitor position relative to a route, perform approach procedures, and identify radio stations by their audio call signs.

ARK-9 use with NDB and approach procedures

In aircraft equipped with ARK-9, the system can be used for en-route navigation, helicopter navigation, aircraft positioning and pre-landing maneuvers. It is especially relevant for approaches based on outer and inner non-directional beacons, where the crew must track the bearing to the selected station during the approach sequence. The unit can be preset to two frequencies, which allows fast switching between two beacons, for example the outer and inner marker stations used in older landing systems. This makes the ARK-9 useful in aircraft that still operate with classic radio-navigation procedures.

Operating modes of the ARK-9 system

The ARK-9 has several working modes. In automatic compass mode, the receiver uses both the loop antenna and the non-directional antenna, and the cockpit indicator shows the bearing to the selected station. In antenna mode, the system works through the non-directional antenna for audio reception, station search, and call-sign identification. In loop mode, the crew can use manual bearing by listening for the minimum signal level while rotating the loop antenna. This manual mode is useful when electrical interference makes automatic bearing less stable.

ARK-9 receiver and antenna equipment

The ARK-9 set includes a receiver, remote control panel, directional loop antenna unit, non-directional antenna equipment, antenna matching or amplifier elements, power supply and switching units. The receiver performs signal selection, amplification and detection. The remote control panel is placed in the cockpit and is used to select frequencies and operating modes. The directional antenna unit contains a rotating loop assembly used for bearing determination, while the non-directional antenna helps remove ambiguity and supports audio reception. Together these blocks form one complete radio compass system.

Cockpit indication with ARK-9

The bearing information from the ARK-9 is displayed on a cockpit course indicator, commonly through instruments such as UGR-4UK or compatible heading / bearing indication equipment, depending on aircraft configuration. The pilot reads the relative bearing to the tuned station and uses it for navigation decisions. Audio output to the pilot’s headset is also important, because beacon identification is done by listening to the station call sign. Without correct audio identification, the bearing may be technically displayed, but the crew cannot be sure that the receiver is tuned to the intended station.

Aircraft application of ARK-9

The ARK-9 was installed on different Soviet and post-Soviet aircraft and helicopters, including An-2, Yak-18T, Yak-40, Mi-2, Mi-8 and other aircraft depending on configuration and modernization status. On helicopters, the radio compass is especially useful for navigation to radio beacons, airfields, temporary landing sites, and route points where older radio-navigation infrastructure is still in use. Before supply or replacement, the exact aircraft type, existing wiring, antenna installation, indicator type and control-panel arrangement should be checked against the aircraft documentation.

Maintenance and supply of ARK-9

The ARK-9 is a multi-block radio-navigation system, so procurement should not be limited to the receiver alone unless the requirement is clearly for a separate replacement block. A complete set may include the receiver, loop antenna, control panel, power supply, antenna units, distribution boxes, control shafts and cabling elements. In maintenance, technicians check receiver operation, tuning, antenna rotation, remote control operation, audio output, bearing accuracy, power supply, connectors and mechanical condition of the installation. For aircraft use, documentation and completeness should be confirmed before shipment.

Product Type: Aircraft automatic direction finder / radio compass
Designation: ARK-9
Function: Automatic determination of relative bearing to ground radio stations; audio reception and beacon identification
Application / Where Used: Aircraft and helicopter navigation systems; approach and pre-landing procedures using NDB / radio beacon stations
System / Installation Area: Radio-navigation equipment; cockpit control and indication system; antenna installation areas
Compatible Aircraft / Equipment: An-2, Yak-18T, Yak-40, Mi-2, Mi-8 and other aircraft depending on configuration
Frequency Range: 150–1300 kHz
Typical Operating Range: About 160 km at 1000 m flight altitude for a 500 W ground station
Preset Frequencies: Two preset channels with fast switching
Frequency Switching Device: DPV remote wave switch
Main Operating Mode: Compass mode / automatic bearing
Additional Operating Mode: Antenna mode for audio reception and station identification
Manual Operating Mode: Loop mode for manual bearing by minimum audio signal
Bearing Indication: Relative bearing displayed on cockpit course indicator
Typical Indicator: UGR-4UK or compatible aircraft bearing indicator depending on installation
DC Power Supply: 28.5 V DC
AC Power Supply: 115 V AC, 400 Hz
Receiver Weight with Shock-Mounting Frame: 11.5 kg
Receiver Dimensions: 208 × 277 × 498 mm
Loop Antenna Unit Weight: 3.5 kg
Loop Antenna Unit Dimensions: 196 × 184 × 244 mm
Power Supply Unit Weight: 1.5 kg
Power Supply Unit Dimensions: Approx. 140 × 170 × 230 mm
Remote Control Panel Weight: 1.3 kg
Remote Control Panel Dimensions: 146 × 145 × 100 mm
Built-in Test Generator Weight: 1.3 kg
Built-in Test Generator Dimensions: 115 × 38 × 222 mm
Antenna Amplifier Weight: 0.5 kg
Antenna Amplifier Dimensions: 66 × 36 × 155 mm
Distribution Box Weight: 0.3 kg
Distribution Box Dimensions: 74 × 82 × 36 mm
Total Set Weight Without Cables and Indicator: 19.65 kg
Main Set Components: Receiver, remote control panel, loop antenna unit, non-directional antenna equipment, antenna matching / amplifier unit, power supply, DPV switch, distribution boxes and connection elements depending on supply configuration
Technical Documentation: Product passport, operating documentation, aircraft installation documentation and test documentation as applicable

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Warranty
All products are covered by a standard 6-month warranty.
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