Sec.  73.1670   Auxiliary transmitters.

   (a) A licensee of a broadcast station may, without further authority from
   the FCC, install and use with the main antenna system one or more auxiliary
   transmitters for the following purposes:

   (1)  The  transmission  of  regular  programs upon failure of the main
   transmitter.

   (2) The transmission of regular programs during maintenance or modification
   of the main transmitter.

   (3) Emergency broadcast system operation.

   (4) The transmission of regular programs by an AM station authorized for
   Presunrise (PSRA) and/or Postsunset (PSSA) operation.

   (5) The transmission of tests to determine the operating condition of the
   auxiliary transmitter or auxiliary antenna.

   (6) For testing, upon the request of representatives of the FCC.

   (b) Authorization to install an auxiliary transmitter for use with other
   than the main antenna or authorized auxiliary antenna must be obtained by
   filing an application for a construction permit on FCC form 301 (FCC form
   340 for noncommercial educational stations).

   (c) The following technical and operating standards apply to auxiliary
   transmitters:

   (1)  The  auxiliary  transmitter may be operated on only the station's
   authorized frequency and within the required carrier frequency departure
   tolerance for the type of station.

   (2) The carrier frequency of the auxiliary transmitter must be measured as
   often as necessary to ensure that it is maintained within the prescribed
   tolerance.

   (3) When using an auxiliary transmitter, the operating power may be less
   than the authorized power but may not exceed the authorized power within the
   permitted tolerance for the type of station. If operation with an auxiliary
   transmitter at reduced power continues for a period exceeding 10 days, the
   FCC  in Washington, DC must be notified. (See  Sec. 73.51, AM;  Sec. 73.267, FM;
    Sec. 73.567, NCE-FM; and  Sec. 73.663, TV).

   (4) Normal operator requirements apply to the operation of the auxiliary
   transmitter.

   Note:  After January 1, 1979, new licenses will not be issued nor will
   existing licenses be renewed for auxiliary transmitters that are operated
   into the main antenna system.

   [ 43 FR 53741 , Nov. 17, 1978, as amended at  44 FR 22740 , Apr. 17, 1979;  48 FR 36463 , Aug. 11, 1983;  48 FR 42960 , Sept. 20, 1983;  48 FR 44806 , Sept. 30,
   1983;  50 FR 32417 , Aug. 12, 1985;  51 FR 32088 , Sept. 9, 1986]