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938 Civil DF.

938 Series Civil DF

The 938 Series of civil Direction Finders (DF) provide a range of integrated DF solutions for bus-controlled and stand-alone direction finding systems. 938 DFs include an integral synthesised receiver covering the frequency range 88 MHz - 470 MHz, together with 5 Guard Receivers to monitor pre-defined distress frequencies. Bearings may be taken on all 6 receivers simultaneously. Data decoding is provided for COSPAS‑SARSAT messages and for marine DSC messages on the associated Guard Receivers. There is also the option to output On Top Position Indication (OTPI).

  • COSPAS-SARSAT decoding
  • Marine DSC decoding
  • Discrete outputs OTPI and distress alert
  • Compatible with Chelton 718-40 DF Controller
  • Discrete OTPI output

The VHF, Maritime and UHF Guard Receivers have a Main channel and an associated Auxiliary channel. The Main channels are pre‑programmed, while the Auxiliary channels can be programmed by the Customer. Such an arrangement allows distress monitoring to take place on the Main frequencies and training to be carried out on selectable Auxiliary frequencies.

The GMDSS DSC Guard Receiver is pre-programmed to the VHF DSC Channel 70. The system may be programmed to monitor and report Distress Alerts, All-Ships Calls, Selective Calls and either Distress or Urgency categories. Full reporting of the vessels MMSI, Nature of Distress and GPS coordinates is made available to the user.

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718 40


  • Electrical Specs
  • Mechanical Specs
  • Standard Specs

Electrical Specs

Minimum Frequency
Maximum Frequency

Mechanical Specs

Full Dimensions LxWxH mm
286 x 286 x 90
Mass kg
Connector Type

Standard Specs

Altitude ft
EUROCAE ED-14G/RTCA DO-160G Sect 8, Cat S, Curve L modified Fixed Wing Curve U2 Helicopter
14043 (2)

Get in touch

Chelton Limited, Marlow HQ
The Chelton Centre
Fourth Avenue
United Kingdom
CAGE Code: U1907