Goto Section: 73.62 | 73.69 | Table of Contents
FCC 73.68
Revised as of October 1, 2010
Goto Year:2009 |
2011
§ 73.68 Sampling systems for antenna monitors.
(a) Each AM station permittee authorized to construct a new directional
antenna system which will be subject to a proof of performance based on
field strength measurements, as described in § 73.151(a) or (b), must
install the sampling system in accordance with the following
specifications:
(1) Devices used to extract or sample the current and the transmission
line connecting the sampling elements to the antenna monitor must
provide accurate and stable signals to the monitor (e.g., rigidly
mounted and non-rotatable loops and all system components protected
from physical and environmental disturbances).
(2) Sampling lines for directional antennas may be of different lengths
provided the phase difference of signals at the monitor are less than
0.5 degrees between the shortest and longest cable lengths due to
temperature variations to which the system is exposed.
(3) Other configurations of sampling systems may be used upon
demonstration of stable operation to the FCC.
(b) An AM station permittee authorized to construct a directional
antenna system which will be subject to a proof of performance based on
moment method modeling, as described in § 73.151(c), shall install a
sampling system conforming to the requirements set forth in that
section.
(c) A station having an antenna sampling system constructed according
to the specifications given in paragraph (a) of this section may obtain
approval of that system by submitting an informal letter request to the
FCC in Washington, DC, Attention: Audio Division, Media Bureau. The
request for approval, signed by the licensee or authorized
representative, must contain sufficient information to show that the
sampling system is in compliance with all requirements of paragraph (a)
of this section.
Note to paragraph (c): A public notice dated December 9, 1985 giving
additional information on approval of antenna sampling systems is
available through the Internet at
http://www.fcc.gov/mb/audio/decdoc/letter/1985-12-09-sample.html.
(d) 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.
(e) If the antenna sampling system is modified or components of the
sampling system are replaced, the following procedure shall be
followed:
(1) Special Temporary Authority (see § 73.1635) shall be requested and
obtained from the Commission's Audio Division, Media Bureau in
Washington to operate with parameters at variance with licensed values
pending issuance of a modified license specifying parameters subsequent
to modification or replacement of components.
(2) Immediately prior to modification or replacement of components of
the sampling system, and after a verification that all monitoring point
values and operating parameters 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. Subsequent to these
modifications or changes the procedure must be repeated.
(3) If monitoring point field strengths or antenna monitor parameters
exceed allowable limits following the replacement or modification of
that portion of the sampling system above the base of the towers, a
partial proof of performance shall be executed in accordance with
§ 73.154 . The partial proof of performance shall be accompanied by
common point impedance measurements made in accordance with § 73.54.
(4) Request for modification of license shall be submitted to the FCC
in Washington, DC, within 30 days of the date of sampling system
modification or replacement. Such request shall specify the transmitter
plate voltage and plate current, common point current, base currents
and their ratios, antenna monitor phase and current indications, and
all other data obtained pursuant to this paragraph.
(f) If an existing sampling system is found to be patently of marginal
construction, or where the performance of a directional antenna is
found to be unsatisfactory, and this deficiency reasonably may be
attributed, in whole or in part, to inadequacies in the antenna
monitoring system, the FCC may require the reconstruction of the
sampling system in accordance with requirements specified above.
[ 41 FR 7405 , Feb. 18, 1976]
Editorial Note: ForFederal Registercitations affecting § 73.68, see
the List of CFR Sections Affected, which appears in the Finding Aids
section of the printed volume and on GPO Access.
Goto Section: 73.62 | 73.69
Goto Year: 2009 |
2011
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