Sec.  73.69   Antenna monitors.

   (a) Each station using a directional antenna must have in operation at the
   transmitter site an FCC authorized antenna monitor.

   (b) In the event that the antenna monitor sampling system is temporarily out
   of service for repair or replacement, the station may be operated, pending
   completion of repairs or replacement, for a period not exceeding 120 days
   without further authority from the FCC if all other operating parameters,
   and the field monitoring point values are within the limits specified on the
   station authorization.

   (c) If conditions beyond the control of the licensee prevent the restoration
   of the monitor to service within the allowed period, an informal letter
   request in accordance with  Sec. 73.3549 of the Commission's rules must be filed
   with the FCC, Attention: Audio Division, Media Bureau in Washington, DC for
   such additional time as may be required to complete repairs of the defective
   instrument.

   (d) If an authorized antenna monitor is replaced by another antenna monitor,
   the following procedure shall be followed:

   (1) Temporary authority shall be requested and obtained from the Commission
   in Washington to operate with parameters at variance with licensed values,
   pending issuance of a modified license specifying new parameters.

   (2) Immediately before the replacement of the antenna monitor, after a
   verification that all monitoring point values and the common point current
   reading are within the limits or tolerances specified in the rules, the
   following indications must be recorded for each radiation pattern: Final
   plate current and plate voltage, common point current, antenna monitor phase
   and current indications, and the field strength at each monitoring point.

   (3) With the new monitor substituted for the old, all indications specified
   in paragraph (d)(2) of this section, again must be read. If no change has
   occurred in the indication for any parameter other than the indications of
   the antenna monitor, the new antenna monitor indications must be deemed to
   be those reflecting correct array adjustments.

   (4) If it cannot be established by the observations required in paragraph
   (d)(2) of this section that the common point current reading and the
   monitoring point values are within the tolerances or limits prescribed by
   the rules and the instrument of authorization, or if the substitution of the
   new antenna monitor for the old results in changes in these parameters, a
   partial proof of performance shall be executed and analyzed in accordance
   with  Sec. 73.154.

   (5) An informal letter request for modification of license shall be
   submitted to the FCC, Attention: Audio Division, Media Bureau in Washington,
   DC within 30 days of the date of monitor replacement. Such request shall
   specify the make, type, and serial number of the replacement monitor, phase
   and sample current indications, and other data obtained pursuant to this
   paragraph (d).

   (e) The antenna monitor must be calibrated according to the manufacturer's
   instructions as often as necessary to ensure its proper operation.

   (Secs. 4, 5, 303, 48 Stat., as amended, 1066, 1068, as amended, 1082, as
   amended; 47 U.S.C. 154, 303. Interpret or apply secs. 301, 303, 307, 48
   Stat. 1081, 1082, as amended, 1083, as amended, 47 U.S.C. 301, 303, 307)

   [ 38 FR 1918 , Jan. 19, 1973, as amended at  40 FR 15884 , Apr. 8, 1975;  40 FR 25459 , June 16, 1975;  40 FR 27939 , July 2, 1975;  41 FR 22942 , June 8, 1976;
    41 FR 32892 , Aug. 6, 1976;  43 FR 4022 , Jan. 31, 1978;  45 FR 26062 , Apr. 17,
   1980;  48 FR 38478 , Aug. 24, 1983;  49 FR 3999 , Feb. 1, 1984;  50 FR 47054 ,
   Nov. 14, 1985;  51 FR 9965 , Mar. 24, 1986;  56 FR 64859 , Dec. 12, 1991;  60 FR 55480 , Nov. 1, 1995;  63 FR 33876 , June 22, 1998;  66 FR 20756 , Apr. 25, 2001;
    67 FR 13231 , Mar. 21, 2002]