47 CFR § 74.1251 - Technical and equipment modifications.
(a) No change, either mechanical or electrical, except as provided in part 2 of this chapter, may be made in FM translator or booster apparatus which has been certificated by the Commission without prior authority of the Commission.
(b) Formal application on FCC Form 349 is required of all permittees and licensees for any of the following changes:
(1) Replacement of the transmitter as a whole, except replacement with a transmitter of identical power rating which has been certificated by the FCC for use by FM translator or FM booster stations, or any change which could result in the electrical characteristics or performance of the station. Upon the installation or modification of the transmitting equipment for which prior FCC authority is not required under the provisions of this paragraph, the licensee shall place in the station records a certification that the new installation complies in all respects with the technical requirements of this part and the terms of the station authorization.
(2) A change in the transmitting antenna system, including the direction of radiation or directive antenna pattern.
(3) Any change in the overall height of the antenna structure except where notice to the Federal Aviation Administration is specifically not required under § 17.14(b) of this chapter.
(4) Any change in the location of the translator or booster except a move within the same building or upon the same pole or tower.
(5) Any horizontal change in the location of the antenna structure which would (i) be in excess of 152.4 meters (500 feet), or (ii) would require notice to the Federal Aviation Administration pursuant to § 17.7 of the FCC's rules.
(6) Any change in the output frequency of a translator.
(7) Any increase of authorized effective radiated power. FM translator and booster stations may decrease ERP on a modification of license application provided that exhibits are included to demonstrate that the following requirements are met:
(i) The license application may not propose to eliminate the authorized horizontally polarized ERP, if a horizontally polarized ERP is currently authorized;
(ii) The installed height of the antenna radiation center is not increased by more than two meters nor decreased by more than four meters from the authorized height for the antenna radiation center; and
(iii) The station is not presently authorized with separate horizontal and vertical antennas mounted at different heights. Use of separate horizontal and vertical antennas requires a construction permit before implementation or changes.
(8) Any change in area being served.
(c) Changes in the primary FM station being retransmitted must be submitted to the FCC in writing.
(d) Any application proposing a change in the height of the antenna structure or its location must also include the Antenna Structure Registration Number (FCC Form 854R) of the antenna structure upon which it proposes to locate its antenna. In the event the antenna structure does not have a Registration Number, either the antenna structure owner shall file FCC Form 854 (“Application for Antenna Structure Registration”) in accordance with part 17 of this chapter or the applicant shall provide a detailed explanation why registration and clearance are not required.
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