Goto Section: 73.1680 | 73.1692 | Table of Contents
Revised as of October 22, 2020
Goto Year:2020 |
§ 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
(2) Those that would cause the transmission system to exceed the
equipment performance measurements prescribed for the class of service
(AM, § 73.44; FM, § § 73.317, 73.319, and 73.322; TV and Class A TV,
§ § 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 § 73.316), or any
increase from the authorized directional antenna pattern for a TV
broadcast (see § 73.685) or Class A TV station (see § 73.6025).
(4) Any change in the directional radiation characteristics of an AM
directional antenna system. See § 73.45 and § 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 § 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 § 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
§ 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 § 73.1690(c)(4), (c)(5), or
(c)(7), or in § 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, § 74.709(a) and
(b) for tables of urban areas and corresponding reference coordinates
of potentially affected land mobile operations).
(9) Any change in the community of license, where the proposed new
facilities are the same as, or would be mutually exclusive with, the
licensee's or permittee's present assignment.
(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 § 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 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 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 § 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 § 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 § 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 § 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 § 73.215 or
§ 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 § 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, § 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 § 73.685(f) or § 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, § 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
§ 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 § 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 § 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 § 73.3555. Program test
operations may commence at full power pursuant to § 73.1620(a)(1).
(6) FM contour protection stations authorized pursuant to § 73.215 which
have become fully spaced under § 73.207 may file a modification of
license application to delete the § 73.215 contour protection
designation with an exhibit to demonstrate that the station is fully
spaced in accordance with § 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 § 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 § 73.215 and which meet the spacing requirements of
§ 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 § 73.1690(c)(1). Program test operations may commence at full power
pursuant to § 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 § 73.213 or short-spaced by a granted waiver of
(ii) If the station is located in or near a radio quiet zone, radio
coordination zone, or a Commission monitoring station (see § 73.1030 and
§ 0.121(c) of this chapter), the licensee or permittee must have secured
written concurrence from the affected radio quiet zone, radio
coordination zone, or the Commission's Public Safety and Homeland
Security 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
§ 73.207(b)(2) and (3) with respect to foreign allotments and
(iv) The increased ERP will not cause the station to violate the
multiple ownership requirements of § 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 five 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
§ 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 § 73.313(b), (c), and (d).
(ii) For commercial FM stations only, there is no change in the
authorized station class as defined in § 73.211.
(iii) For commercial FM stations only, the power decrease is not
necessary to achieve compliance with the multiple ownership rule,
(iv) 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 § 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.
(v) Noncommercial educational FM stations on Channels 201 through 220
which are within the Table A distance separations of § 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) Commencement of remote control operation pursuant to § 73.1400.
(2) Modification of an AM directional antenna sampling system. See
(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
§ 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 § 73.1690, see
the List of CFR Sections Affected, which appears in the Finding Aids
section of the printed volume and at www.govinfo.gov.
Goto Section: 73.1680 | 73.1692
Goto Year: 2020 |
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