§ 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 § 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/m2, pursuant to §§ 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 § 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 § 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 § 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.