Sec.  73.62   Directional antenna system tolerances.

   (a) Each AM station operating a directional antenna must maintain the
   indicated relative amplitudes of the antenna monitor currents within 5% of
   the values specified therein. Directional antenna relative phase currents
   must be maintained to within  ±3 deg. of the values specified on the
   instrument of authorization.

   (b) Whenever the operating parameters of a directional antenna cannot be
   maintained within the tolerances specified in paragraph (a) of this section,
   the following procedures will apply:

   (1) The licensee shall measure and log every monitoring point at least once
   for each mode of directional operation. Subsequent variations in operating
   parameters will require the remeasuring and logging of every monitoring
   point to assure that the authorized monitoring point limits are not being
   exceeded.

   (2) Provided each monitoring point is within its specified limit, operation
   may continue for a period up to 30 days before a request for Special
   Temporary Authority (STA) must be filed, pursuant to paragraph (b)(4) of
   this section, to operate with parameters at variance from the provisions of
   paragraph (a) of this section.

   (3) If any monitoring point exceeds its specified limit, the licensee must
   either terminate operation within 3 hours or reduce power in accordance with
   the applicable provisions of  Sec. 73.1350(d), in order to eliminate any
   possibility of interference or excessive radiation in any direction.

   (4) If operation pursuant to paragraph (b)(3) of this section is necessary,
   or before the 30 day period specified in paragraph (b)(2) of this section
   expires, the licensee must request a Special Temporary Authority (STA) in
   accordance with  Sec. 73.1635 to continue operation with parameters at variance
   and/or with reduced power along with a statement certifying that all
   monitoring points will be continuously maintained within their specified
   limits.

   (5) The licensee will be permitted 24 hours to accomplish the actions
   specified in paragraph (b)(1) of this section; provided that, the date and
   time of the failure to maintain proper operating parameters has been
   recorded in the station log.

   (c) In any other situation in which it might reasonably be anticipated that
   the operating parameters might vary out of tolerance (such as planned array
   repairs or adjustment and proofing procedures), the licensee shall, before
   such activity is undertaken, obtain an STA in accordance with  Sec. 73.1635 in
   order to operate with parameters at variance and/or with reduced power as
   required to maintain all monitoring points within their specified limits.

   [ 50 FR 30946 , July 31, 1985, as amended at  60 FR 55480 , Nov. 1, 1995;  66 FR 20755 , Apr. 25, 2001]