§  73.72   Operating during the experimental period.

   (a) An AM station may operate during the experimental period (the time
   between midnight and sunrise, local time) on its assigned frequency and
   with its authorized power for the routine testing and maintenance of
   its transmitting system, and for conducting experimentation under an
   experimental authorization, provided no interference is caused to other
   stations maintaining a regular operating schedule within such period.

   (b) No station licensed for “daytime” or “specified hours” of operation
   may broadcast any regular or scheduled program during this period.

   (c) The licensee of an AM station shall operate or refrain from
   operating its station during the experimental period as directed by the
   FCC to facilitate frequency measurements or for the determination of
   interference.

   [ 43 FR 32780 , July 28, 1978, as amended at  56 FR 64859 , Dec. 12, 1991]