Sec.  73.62   Directional antenna system operation and tolerances.

   (a)  Each AM station operating a directional antenna must maintain the
   relative amplitudes of the antenna currents, as indicated by the antenna
   monitor,  within  5%  of  the  values  specified  on the instrument of
   authorization. Directional antenna relative phases must be maintained within
   3 degrees of the values specified on the instrument of authorization.

   (b)  In  the event of a failure of system components, improper pattern
   switching or any other event that results in operation substantially at
   variance  from  the  radiation  pattern specified in the instrument of
   authorization for the pertinent time of day, operation must be terminated
   within three minutes unless power can be reduced sufficiently to eliminate
   any excessive radiation. See  Sec. 73.1350(e).

   (1) Any variation of operating parameters by more than  ±15 percent sample
   current ratio or  ±10 degrees in phase, any monitor point that exceeds 125
   percent of the licensed limit, or any operation at variance that results in
   complaints of interference shall be considered operation substantially at
   variance from the license and will require immediate corrective action.

   (2) [Reserved]

   (c)  In the event of minor variations of directional antenna operating
   parameters from 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.  The licensee will be permitted 24 hours to accomplish these
   actions; provided that, the date and time of the failure to maintain proper
   operating parameters have been recorded in the station log.

   (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 (c)(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 three 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 (c)(3) of this section is necessary,
   or before the 30-day period specified in paragraph (c)(2) of this  Sec. expires,
   the licensee must request a Special Temporary Authority (STA) in accordance
   with section 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.

   (d) 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 a Special Temporary Authority (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.

   [ 72 FR 44422 , Aug. 8, 2007]