Sec.  80.289   Requirements for radio direction finder.

   (a) The radio direction finding apparatus must:

   (1) Be capable of receiving signals A1A, A2B and R2B emission, on each
   frequency within the band 285–515 kHz assigned by the Radio Regulations for
   distress  and direction finding and for maritime radio beacons, and be
   calibrated to take bearings on such signals from which the true bearing and
   direction may be determined; and

   (2) Possess a sensitivity, sufficient to permit the taking of bearings on a
   signal having a field strength of 50 microvolts per meter.

   (b)  The calibration of the direction finder must be verified by check
   bearings or by a further calibration whenever any changes are made in the
   physical or electrical characteristics or the position of any antennas, and
   whenever any changes are made in the position of any deck structures which
   might  affect  the  accuracy of the direction finder. In addition, the
   calibration must be verified by check bearings at yearly intervals. A record
   of the calibrations, and of the check bearings made of their accuracy and
   the accuracy of the check bearings must be kept on board the ship for a
   period of not less than 1 year.

   [ 51 FR 31213 , Sept. 2, 1986, as amended at  63 FR 29660 , June 1, 1998.
   Redesignated at  68 FR 46973 , Aug. 7, 2003]