Sec.  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  Sec. 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  Sec. 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  Sec. 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  Sec. 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  Sec. 73.872.