47 CFR § 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, for applications filed solely pursuant to paragraphs (c)(1) or (2) of this section, where the installation is on or near an AM tower, as defined in § 1.30002, an exhibit demonstrating compliance with § 1.30003 or § 1.30002, as applicable, 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.