§  73.875   Modification of transmission systems.

   The following procedures and restrictions apply to licensee
   modifications of authorized broadcast transmission system facilities.

   (a) The following changes are prohibited:

   (1) Those that would result in the emission of signals outside of the
   authorized channel exceeding limits prescribed for the class of
   service.

   (2) Those that would cause the transmission system to exceed the
   equipment performance measurements prescribed in § 73.508.

   (b) The following changes may be made only after the grant of a
   construction permit application on FCC Form 318.

   (1) Any construction of a new tower structure for broadcast purposes,
   except for replacement of an existing tower with a new tower of
   identical height and geographic coordinates.

   (2) Any change in station geographic coordinates, including coordinate
   corrections and any move of the antenna to another tower structure
   located at the same coordinates.

   (3) Any change in antenna height more than 2 meters above or 4 meters
   below the authorized value.

   (4) Any change in channel.

   (c) The following LPFM modifications may be made without prior
   authorization from the Commission. A modification of license
   application (FCC Form 319) must be submitted to the Commission within
   10 days of commencing program test operations pursuant to § 73.1620.
   For applications filed pursuant to paragraph (c)(1) of this section,
   the modification of license application must contain an exhibit
   demonstrating compliance with the Commission's radiofrequency radiation
   guidelines. In addition, applications solely filed pursuant to
   paragraphs (c)(1) or (c)(2) of this section, where the installation is
   located within 3.2 km of an AM tower or is located on an AM tower, an
   exhibit demonstrating compliance with § 73.1692 is also required.

   (1) Replacement of an antenna with one of the same or different number
   of antenna bays, provided that the height of the antenna radiation
   center is not more than 2 meters above or 4 meters below the authorized
   values. Program test operations at the full authorized ERP may commence
   immediately upon installation pursuant to § 73.1620(a)(1).

   (2) Replacement of a transmission line with one of a different type or
   length which changes the transmitter operating power (TPO) from the
   authorized value, but not the ERP, must be reported in a license
   modification application to the Commission.

   (3) Changes in the hours of operation of stations authorized pursuant
   to time-share agreements in accordance with § 73.872.