Sec.  21.42   Certain modifications not requiring prior authorization.

   

   (a) Equipment in an authorized radio station may be replaced without
   prior authorization or notification if:

   (1) The replacement equipment is identical (i.e., same manufacturer
   and model number) with the replacement equipment; or

   (2) The replacement transmitter, transmitting antenna, transmission
   line loss and/or devices between the transmitter and antenna, or
   combinations of the above, do not change the EIRP of a station in any
   direction.

   (b) Licensees of fixed stations in the Multipoint Distribution Service
   may make the facility changes listed in paragraph (c) of this section
   without obtaining prior Commission authorization, if:

   (1) The Multipoint Distribution Service licensee serves a copy of the
   notification described in paragraph (b)(3) of this section on those
   who were served under Sec. 21.902, and

   (2) The cumulative effect of all facility changes made within any 60
   day period does not exceed the appropriate values prescribed by
   paragraph (c) of this section, and

   (3) The Commission is notified of changes made to facilities by the
   submission of a completed FCC Form 304 within thirty (30) days after
   the changes are made.

   (4) In the Multipoint Distribution Service, the modified facility
   would not produce a power flux density at the protected service area
   boundary that exceeds -73 dBW/m 2 , pursuant to Sec. Sec. 21.902 and 21.939.

   (c) Modifications that may be made without prior authorization under
   paragraph (b) of this section are:

   (1) Change or modification of a transmitter, when:

   (i) The replacement or modified transmitter is certificated for use
   under this part and is installed without modification from the
   certificated configuration;

   (ii) The type of modulation is not changed;

   (iii) The frequency stability is equal to or better than the
   previously authorized frequency stability; and

   (iv) The necessary bandwidth and the output power do not exceed the
   previously authorized values.

   (2) Addition or deletion of a transmitter for protection without
   changing the authorized power output (e.g. hot standby transmitters);

   (3) Change to an antenna when the new antenna conforms with Sec. 21.906
   and the EIRP resulting from the new antenna does not exceed that
   resulting from the previously authorized antenna by more than one dB
   in any direction.

   (4) Any technical changes that would decrease the effective radiated
   power.

   (5) Change to the height of an antenna, when:

   (i) The new height (measured at the center-of-radiation) is within
   ±1.5 meters (5 feet) of the previously authorized height; and

   (ii) The overall height of the antenna structure is not increased as a
   result of the antenna extending above the height of the previously
   authorized structure, except when the new height of the antenna
   structure is 6.1 meters (20 feet) or less (above ground or man-made
   structure, as appropriate) after the change is made.

   (6) Decreases in the overall height of an antenna structure, provided
   that, when notice to the FAA of proposed construction was required by
   part 17 of this chapter for the antenna structure at the previously
   authorized height, the applicant must comply with the provisions of
   Sec. 21.15 (d) and (e).

   (7) Changes to the transmission line and other devices between the
   transmitter and the antenna when the effective radiated power of the
   station is not increased by more than one dB.

   (8) A change to a sectorized antenna system comprising an array of
   directional antennas, provided that such system does not change
   polarization or result in an increase in radiated power by more than
   one dB in any horizontal or vertical direction; provided, however,
   that notice of such change is provided to the Commission on FCC Form
   331 within ten (10) days of installation.

   (d) Licensees may correct erroneous information on a license which
   does not involve a major change (i.e., a change that would be
   classified as a major amendment as defined by Sec. 21.23) without
   obtaining prior Commission approval by filing a completed FCC Form
   494, or for the Multipoint Distribution Service licensees, by filing
   the MDS long-form application.

   [ 52 FR 37781 , Oct. 9, 1987, as amended at  58 FR 44894 , Aug. 25, 1993;
    60 FR 36552 , July 17, 1995;  60 FR 57366 , Nov. 15, 1995;  61 FR 4364 ,
   Feb. 6, 1996;  61 FR 26674 , May 28, 1996;  63 FR 36603 , July 7, 1998;  63 FR 49870 , Sept. 18, 1998;  63 FR 65101 , Nov. 25, 1998;  64 FR 4054 , Jan.
   27, 1999;  65 FR 46617 , July 31, 2000]