§  73.1560   Operating power and mode tolerances.

   (a) AM stations. (1) Except for AM stations using modulation dependent
   carrier level (MDCL) control technology, or as provided for in
   paragraph (d) of this section, the antenna input power of an AM
   station, as determined by the procedures specified in § 73.51, must be
   maintained as near as practicable to the authorized antenna input power
   and may not be less than 90 percent nor greater than 105 percent of the
   authorized power. AM stations may, without prior Commission authority,
   commence MDCL control technology use, provided that within 10 days
   after commencing such operation, the licensee submits an electronic
   notification of commencement of MDCL control operation using FCC Form
   338. The transmitter of an AM station operating using MDCL control
   technology, regardless of the MDCL control technology employed, must
   achieve full licensed power at some audio input level or when the MDCL
   control technology is disabled. MDCL control operation must be disabled
   before field strength measurements on the station are taken.

   (2) Whenever the transmitter of an AM station cannot be placed into the
   specified operating mode at the time required, transmissions of the
   station must be immediately terminated. However, if the radiated field
   at any bearing or elevation does not exceed that permitted for that
   time of day, operation in the mode with the lesser radiated field may
   continue under the notification procedures of paragraph (d) of this
   section.

   (b) FM stations. Except as provided in paragraph (d) of this section,
   the transmitter output power of an FM station, with power output as
   determined by the procedures specified in § 73.267, which is authorized
   for output power more than 10 watts must be maintained as near as
   practicable to the authorized transmitter output power and may not be
   less than 90% nor more than 105% of the authorized power. FM stations
   operating with authorized transmitter output power of 10 watts or less,
   may operate at less than the authorized power, but not more than 105%
   of the authorized power.

   (c) TV stations. (1) Except as provided in paragraph (d) of this
   section, the visual output power of a TV or Class A TV transmitter, as
   determined by the procedures specified in Sec. 73.664, must be
   maintained as near as is practicable to the authorized transmitter
   output power and may not be less than 80% nor more than 110% of the
   authorized power.

   (2) The output power of the aural transmitter shall be maintained to
   provide an aural carrier ERP not to exceed 22% of the peak authorized
   visual ERP.

   (3) The FCC may specify deviation from the power of tolerance
   requirements for subscription television operations to the extent it
   deems necessary to permit proper operation.

   (d) Reduced power operation. In the event it becomes technically
   impossible to operate at authorized power, a broadcast station may
   operate at reduced power for a period of not more than 30 days without
   specific authority from the FCC. If operation at reduced power will
   exceed 10 consecutive days, notification must be made to the FCC in
   Washington, DC, Attention: Audio Division (radio) or Video Division
   (television), Media Bureau, not later than the 10th day of the lower
   power operation. In the event that normal power is restored within the
   30 day period, the licensee must notify the FCC of the date that normal
   operation was restored. If causes beyond the control of the licensee
   prevent restoration of the authorized power within 30 days, a request
   for Special Temporary Authority (see § 73.1635) must be made to the FCC
   in Washington, DC for additional time as may be necessary.

   [ 44 FR 58734 , Oct. 11, 1979, as amended at  49 FR 22093 , May 25, 1984;
    49 FR 29069 , July 18, 1984;  49 FR 47610 , Dec. 6, 1984;  50 FR 26568 ,
   June 27, 1985;  50 FR 40015 , Oct. 1, 1985;  63 FR 33877 , June 22, 1998;
    65 FR 30004 , May 10, 2000;  67 FR 13232 , Mar. 21, 2002;  81 FR 2760 , Jan.
   19, 2016]