(a) Installations on a nondirectional AM tower. When antennas are installed on a nondirectional AM tower the AM station shall determine the operating power by the indirect method (see §73.51 of this chapter). Upon completion of the installation, antenna impedance measurements on the AM antenna shall be made. If the resistance of the AM antenna changes by more than 2 percent (see §73.45(c)(1) of this chapter), an application on FCC Form 302-AM (including a tower sketch of the installation) shall be filed with the Commission for the AM station to return to direct power measurement.

(b) Installations on a directional AM array. Before antennas are installed on a tower in a directional AM array, the proponent shall notify the AM station so that, if necessary, the AM station may determine operating power by the indirect method (see §73.51 of this chapter) and request special temporary authority pursuant to §73.1635 of this chapter to operate with parameters at variance.

(1) For AM stations licensed via field strength measurements (see §73.151(a)), a partial proof of performance as defined by §73.154 of this chapter shall be conducted by the tower proponent both before and after construction to establish that the AM array will not be and has not been adversely affected. If the operating parameters of the AM array change following the installation, the results of the partial proof of performance shall be filed by the AM station with the Commission on Form 302-AM.

(2) For AM stations licensed via a moment method proof (see §73.151(c) of this chapter), a base impedance measurement on the tower being modified shall be made by the tower proponent as described in §73.151(c)(1). The result of the new tower impedance measurement shall be retained in the station's records. If the new measured base resistance and reactance values of the affected tower differ by more than ±2 ohms and ±4 percent from the corresponding modeled resistance and reactance values contained in the last moment method proof, then the station shall file Form 302-AM. The Form 302-AM shall be accompanied by the new impedance measurements for the modified tower and a new moment method model for each pattern in which the tower is a radiating element. Base impedance measurements for other towers in the array, sampling system measurements, and reference field strength measurements need not be repeated. The procedures described in this paragraph may be used as long as the affected tower continues to meet the requirements for moment method proofing after the modification.

(c) Form 302-AM Filing. When the AM station is required to file Form 302-AM following an installation as set forth in paragraphs (a) and (b) of this section, the Form 302-AM shall be filed before or simultaneously with any license application associated with the installation. If no license application is filed as a result of the installation, the Form 302-AM shall be filed within 30 days after the completion of the installation.

[78 FR 66295, Nov. 5, 2013]