§  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 § 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 § 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.

   [ 38 FR 1918 , Jan. 19, 1973]

   Editorial Note: For Federal Register citations affecting § 73.69, see
   the List of CFR Sections Affected, which appears in the Finding Aids
   section of the printed volume and at www.govinfo.gov.