Sec.  73.1690   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 for the class of service (AM,  Sec. 73.44;
   FM,  Sec.  Sec. 73.317, 73.319, and 73.322; TV and Class A TV,  Sec.  Sec. 73.682 and 73.687).

   (b) The following changes may be made only after the grant of a construction
   permit application on FCC Form 301 for commercial stations or Form 340 for
   noncommercial educational stations:

   (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 of more than 3 seconds latitude and/or 3 seconds longitude. FM
   and TV directional stations must also file a construction permit application
   for any move of the antenna to another tower structure located at the same
   coordinates.

   (3) Any change which would require an increase along any azimuth in the
   composite directional antenna pattern of an FM station from the composite
   directional antenna pattern authorized (see  Sec. 73.316), or any increase from
   the authorized directional antenna pattern for a TV broadcast (see  Sec. 73.685)
   or Class A TV station (see  Sec. 73.6025).

   (4) Any change in the directional radiation characteristics of an AM
   directional antenna system. See  Sec. 73.45 and  Sec. 73.150.

   (5) Any decrease in the authorized power of an AM station or the ERP of a TV
   or Class A TV station, or any decrease or increase in the ERP of an FM
   commercial station, which is intended for compliance with the multiple
   ownership rules in  Sec. 73.3555.

   (6) For FM noncommercial educational stations, any of the following:

   (i) Any increase in the authorized maximum ERP, whether horizontally or
   vertically polarized, for a noncommercial educational FM station operating
   on Channels 201 through 220, or a Class D FM station operating on Channel
   200.

   (ii) For those FM noncommercial educational stations on Channels 201 to 220,
   or a Class D FM station operating on Channel 200, which are within the
   separation distances specified in Table A of  Sec. 73.525 with respect to a
   Channel 6 television station, any increase in the horizontally or vertically
   polarized ERP from the presently authorized ERP.

   (iii) For those FM noncommercial educational stations on Channels 201
   through 220 which are located within the separation distances in  Sec. 73.525
   with respect to a Channel 6 television station, or a Class D FM station
   operating on Channel 200, any decrease in the presently authorized
   horizontal effective radiated power which would eliminate the horizontal ERP
   to result in use of vertical ERP only.

   (iv) For those FM noncommercial educational stations which employ separate
   antennas for the horizontal ERP and the vertical ERP, mounted at different
   heights, the station may not increase or decrease either the horizontal ERP
   or the vertical ERP without a construction permit.

   (7) Any increase in the authorized ERP of a television station, Class A
   television station, FM commercial station, or noncommercial educational FM
   station, except as provided for in  Sec.  Sec. 73.1690(c)(4), (c)(5), or (c)(7), or in
    Sec. 73.1675(c)(1) in the case of auxiliary facilities.

   (8) A commercial TV or noncommercial educational TV station operating on
   Channels 14 or Channel 69 or a Class A TV station on Channel 14 may increase
   its horizontally or vertically polarized ERP only after the grant of a
   construction permit. A television or Class A television station on Channels
   15 through 21 within 341 km of a cochannel land mobile operation, or 225 km
   of a first-adjacent channel land mobile operation, must also obtain a
   construction permit before increasing the horizontally or vertically
   polarized ERP (see part 74,  Sec. 74.709(a) and (b) for tables of urban areas and
   corresponding reference coordinates of potentially affected land mobile
   operations).

   (c) The following FM, TV and Class A TV station modifications may be made
   without prior authorization from the Commission. A modification of license
   application must be submitted to the Commission within 10 days of commencing
   program test operations pursuant to  Sec. 73.1620. With the exception of
   applications filed solely pursuant to paragraphs (c)(6), (c)(9), or (c)(10)
   of this section, the modification of license application must contain an
   exhibit demonstrating compliance with the Commission's radio frequency
   radiation guidelines. In addition, except for applications solely filed
   pursuant to paragraphs (c)(6) or (c)(9) 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 omnidirectional 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. Any concurrent change in ERP must comply with
    Sec. 73.1675(c)(1), 73.1690(4), (c)(5), or (c)(7). Program test operations at
   the full authorized ERP may commence immediately upon installation pursuant
   to  Sec. 73.1620(a)(1).

   (2) Replacement of a directional FM antenna, where the measured composite
   directional antenna pattern does not exceed the licensed composite
   directional pattern at any azimuth, where no change in effective radiated
   power will result, and where compliance with the principal coverage
   requirements of  Sec. 73.315(a) will be maintained by the measured directional
   pattern. The antenna must be mounted not more than 2 meters above or 4
   meters below the authorized values. The modification of license application
   on Form 302-FM to cover the antenna replacement must contain all of the data
   in the following sections (i) through (v). Program test operations at one
   half (50%) power may commence immediately upon installation pursuant to
    Sec. 73.1620(a)(3). However, if the replacement directional antenna is an exact
   replacement (i.e., no change in manufacturer, antenna model number, AND
   measured composite antenna pattern), program test operations may commence
   immediately upon installation at the full authorized power.

   (i) A measured directional antenna pattern and tabulation on the antenna
   manufacturer's letterhead showing both the horizontally and vertically
   polarized radiation components and demonstrating that neither of the
   components exceeds the authorized composite antenna pattern along any
   azimuth.

   (ii) Contour protection stations authorized pursuant to  Sec. 73.215 or  Sec. 73.509
   must attach a showing that the RMS (root mean square) of the composite
   measured directional antenna pattern is 85% or more of the RMS of the
   authorized composite antenna pattern. See  Sec. 73.316(c)(9). If this requirement
   cannot be met, the licensee may include new relative field values with the
   license application to reduce the authorized composite antenna pattern so as
   to bring the measured composite antenna pattern into compliance with the 85
   percent requirement.

   (iii) A description from the manufacturer as to the procedures used to
   measure the directional antenna pattern. The antenna measurements must be
   performed with the antenna mounted on a tower, tower section, or scale model
   equivalent to that on which the antenna will be permanently mounted, and the
   tower or tower section must include transmission lines, ladders, conduits,
   other antennas, and any other installations which may affect the measured
   directional pattern.

   (iv) A certification from a licensed surveyor that the antenna has been
   oriented to the proper azimuth.

   (v) A certification from a qualified engineer who oversaw installation of
   the directional antenna that the antenna was installed pursuant to the
   manufacturer's instructions.

   (3) A directional TV on Channels 2 through 13 or 22 through 68 or a
   directional Class A TV on Channels 2 through 13 or 22 through 51, or a
   directional TV or Class A TV station on Channels 15 through 21 which is in
   excess of 341 km (212 miles) from a cochannel land mobile operation or in
   excess of 225 km (140 miles) from a first-adjacent channel land mobile
   operation (see part 74,  Sec. 74.709(a) and (b) for tables of urban areas and
   reference coordinates of potentially affected land mobile operations), may
   replace a directional TV or Class A TV antenna by a license modification
   application, if the proposed horizontal theoretical directional antenna
   pattern does not exceed the licensed horizontal directional antenna pattern
   at any azimuth and where no change in effective radiated power will result.
   The modification of license application on Form 302–TV or Form 302–CA must
   contain all of the data set forth in  Sec. 73.685(f) or  Sec. 73.6025(a), as
   applicable.

   (4) Commercial and noncommercial educational FM stations operating on
   Channels 221 through 300 (except Class D), NTSC TV stations operating on
   Channels 2 through 13 and 22 through 68, Class A TV stations operating on
   Channels 2 through 13 and 22 through 51, and TV and Class A TV stations
   operating on Channels 15 through 21 that are in excess of 341 km (212 miles)
   from a cochannel land mobile operation or in excess of 225 km (140 miles)
   from a first-adjacent channel land mobile operation (see part 74,  Sec. 74.709(a)
   and (b) for tables of urban areas and reference coordinates of potentially
   affected land mobile operations), which operate omnidirectionally, may
   increase the vertically polarized effective radiated power up to the
   authorized horizontally polarized effective radiated power in a license
   modification application. Noncommercial educational FM licensees and
   permittees on Channels 201 through 220, that do not use separate antennas
   mounted at different heights for the horizontally polarized ERP and the
   vertically polarized ERP, and are located in excess of the separations from
   a Channel 6 television station listed in Table A of  Sec. 73.525(a)(1), may also
   increase the vertical ERP, up to (but not exceeding) the authorized
   horizontally polarized ERP via a license modification application. Program
   test operations may commence at full power pursuant to  Sec. 73.1620(a)(1).

   (5) Those Class A FM commercial stations which were permitted to increase
   ERP pursuant to MM Docket No. 88–375 by a modification of license
   application remain eligible to do so, provided that the station meets the
   requirements of  Sec. 73.1690 (c)(1) and is listed on one of the Public Notices
   as authorized to increase ERP, or by a letter from the Commission's staff
   authorizing the change. These Public Notices were released on November 3,
   1989; November 17, 1989; December 8, 1989; March 2, 1990; and February 11,
   1991. The increased ERP must comply with the multiple ownership requirements
   of  Sec. 73.3555. Program test operations may commence at full power pursuant to
    Sec. 73.1620(a)(1).

   (6) FM contour protection stations authorized pursuant to  Sec. 73.215 which have
   become fully spaced under  Sec. 73.207 may file a modification of license
   application to delete the  Sec. 73.215 contour protection designation with an
   exhibit to demonstrate that the station is fully spaced in accordance with
    Sec. 73.207. The contour protection designation will be removed upon grant of
   the license application. Applications filed under this rule section will be
   processed on a first come / first served basis with respect to conflicting
   FM commercial minor change applications and modification of license
   applications (including those filed pursuant to  Sec. 73.1690 (b) and (c)(6) and
   (c)(7)).

   (7) FM omnidirectional commercial stations, and omnidirectional
   noncommercial educational FM stations operating on Channels 221 through 300
   (except Class D), which are not designated as contour protection stations
   pursuant to  Sec. 73.215 and which meet the spacing requirements of  Sec. 73.207, may
   file a license modification application to increase ERP to the maximum
   permitted for the station class, provided that any change in the height of
   the antenna radiation center remains in accordance with  Sec. 73.1690(c)(1).
   Program test operations may commence at full power pursuant to
    Sec. 73.1620(a)(1). All of the following conditions also must be met before a
   station may apply pursuant to this section:

   (i) The station may not be a “grandfathered” short-spaced station authorized
   pursuant to  Sec. 73.213 or short-spaced by a granted waiver of  Sec. 73.207;

   (ii) If the station is located in or near a radio quiet zone, radio
   coordination zone, or a Commission monitoring station (see  Sec. 73.1030 and
    Sec. 0.121(c)), the licensee or permittee must have secured written concurrence
   from the affected radio quiet zone, radio coordination zone, or the
   Commission's Compliance and Information Bureau in the case of a monitoring
   station, to increase effective radiated power PRIOR to implementation. A
   copy of that concurrence must be submitted with the license application to
   document that concurrence has been received;

   (iii) The station does not require international coordination as the station
   does not lie within the border zones, or clearance has been obtained from
   Canada or Mexico for the higher power operation within the station's
   specified domestic class and the station complies with  Sec. 73.207(b)(2) and (3)
   with respect to foreign allotments and allocations;

   (iv) The increased ERP will not cause the station to violate the multiple
   ownership requirements of  Sec. 73.3555.

   (8) FM commercial stations and FM noncommercial educational stations may
   decrease ERP on a modification of license application provided that exhibits
   are included to demonstrate that all six of the following requirements are
   met:

   (i) Commercial FM stations must continue to provide a 70 dBu principal
   community contour over the community of license, as required by  Sec. 73.315(a).
   Noncommercial educational FM stations must continue to provide a 60 dBu
   contour over at least a portion of the community of license. The 60 and 70
   dBu contours must be predicted by use of the standard contour prediction
   method in  Sec. 73.313(b), (c), and (d).

   (ii) For both commercial FM and noncommercial educational FM stations, the
   location of the main studio remains within the 70 dBu principal community
   contour, as required by  Sec. 73.1125, or otherwise complies with that rule. The
   70 dBu contour must be predicted by use of the standard contour prediction
   method in  Sec. 73.313(b), (c), and (d).

   (iii) For commercial FM stations only, there is no change in the authorized
   station class as defined in  Sec. 73.211.

   (iv) For commercial FM stations only, the power decrease is not necessary to
   achieve compliance with the multiple ownership rule,  Sec. 73.3555.

   (v) Commercial FM stations, noncommercial educational FM stations on
   Channels 221 through 300, and noncommercial educational FM stations on
   Channels 200 through 220 which are located in excess of the distances in
   Table A of  Sec. 73.525 with respect to a Channel 6 TV station, may not use this
   rule to decrease the horizontally polarized ERP below the value of the
   vertically polarized ERP.

   (vi) Noncommercial educational FM stations on Channels 201 through 220 which
   are within the Table A distance separations of  Sec. 73.525, or Class D stations
   on Channel 200, may not use the license modification process to eliminate an
   authorized horizontally polarized component in favor of vertically
   polarized-only operation. In addition, noncommercial educational stations
   operating on Channels 201 through 220, or Class D stations on Channel 200,
   which employ separate horizontally and vertically polarized antennas mounted
   at different heights, may not use the license modification process to
   increase or decrease either the horizontal ERP or vertical ERP without a
   construction permit.

   (9) The licensee of an AM, FM, or TV commercial station may propose to
   change from commercial to noncommercial educational on a modification of
   license application, provided that the application contains completed
   Sections II and IV of FCC Form 340. In addition, a noncommercial educational
   AM licensee, a TV licensee on a channel not reserved for noncommercial
   educational use, or an FM licensee on Channels 221 to 300 (except Class D
   FM) on a channel not reserved for noncommercial educational use, may apply
   to change from educational to commercial via a modification of license
   application, and no exhibits are required with the application. The change
   will become effective upon grant of the license application.

   (10) 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.

   (11) Correction of geographic coordinates where the change is 3 seconds or
   fewer in latitude and/or 3 seconds or fewer in longitude, provided there is
   no physical change in location and no other licensed parameters are changed.
   The correction of coordinates may not result in any new short spacings or
   increases in existing short spacings.

   (d) The following changes may be made without authorization from the FCC,
   however informal notification of the changes must be made according to the
   rule sections specified:

   (1) Change in studio location within the principal community contour. See
    Sec. 73.1125.

   (2) Commencement of remote control operation pursuant to  Sec.  Sec. 73.1400 and
   73.1410.

   (3) Modification of an AM directional antenna sampling system. See  Sec. 73.68.

   (e) Any electrical and mechanical modification to authorized transmitting
   equipment that is not otherwise restricted by the preceding provisions of
   this section, may be made without FCC notification or authorization.
   Equipment performance measurements must be made within ten days after
   completing the modifications (See  Sec. 73.1590). An informal statement, diagram,
   etc., describing the modification must be retained at the transmitter site
   for as long as the equipment is in use.

   [ 47 FR 8590 , Mar. 1, 1982]

   Editorial Note:   For Federal Register citations affecting  Sec. 73.1690, see the
   List of CFR Sections Affected, which appears in the Finding Aids section of
   the printed volume and on GPO Access.