Sec.  74.750   Transmission system facilities.

   (a) A low power TV, TV translator, or TV booster station shall operate with
   a transmitter that is either certificated for licensing under the provisions
   of this subpart or type notified for use under part 73 of this chapter.

   (b) Transmitting antennas, antennas used to receive the signals to be
   rebroadcast, and transmission lines are not certificated by the FCC.
   External preamplifiers also may be used provided that they do not cause
   improper operation of the transmitting equipment, and use of such
   preamplifiers is not necessary to meet the provisions of paragraph (c) of
   this section.

   (c) The following requirements must be met before low power TV and TV
   translator transmitters will be certificated by the FCC:

   (1) The equipment shall be so designed that the electrical characteristics
   of a standard television signal introduced into the input terminals will be
   maintained at the output. The overall response of the apparatus within its
   assigned channel, when operating at its rated power output and measured at
   the output terminals, shall provide a smooth curve, varying within limits
   separated by no more than 4 dB: Provided, however, That means may be
   provided to reduce the amplitude of the aural carrier below those limits, if
   necessary to prevent intermodulation which would mar the quality of the
   retransmitted picture or result in emissions outside of the assigned
   channel.

   (2) Radio frequency harmonics of the visual and aural carriers, measured at
   the output terminals of the transmitter, shall be attenuated no less than 60
   dB below the peak visual output power within the assigned channel. All other
   emissions appearing on frequencies more than 3 megacycles above or below the
   upper and lower edges, respectively, of the assigned channel shall be
   attenuated no less than:

   (i) 30 dB for transmitters rated at no more than 1 watt power output.

   (ii) 50 dB for transmitters rated at more than 1 watt power output.

   (iii) 60 dB for transmitters rated at more than 100 watts power output.

   (3) When subjected to variations in ambient temperature between minus 30
   degrees and plus 50 degrees Centigrade and variations in power main voltage
   between 85 percent and 115 percent of rated power supply voltage, the local
   oscillator frequency stability shall maintain the operating frequency
   within:

   (i) 0.02 percent of its rated frequency for transmitters rated at no more
   than 100 watts peak visual power.

   (ii) 0.002 percent of the rated frequency for transmitters rated at more
   than 100 watts peak visual power.

   (iii) Plus or minus 1 kHz of its rated frequency for transmitters to be used
   at stations employing offset carrier frequency operation.

   (4) The apparatus shall contain automatic circuits which will maintain the
   peak visual power output constant within 2 dB when the strength of the input
   signal is varied over a range of 30 dB and which will not permit the peak
   visual power output to exceed the maximum rated power output under any
   condition. If a manual adjustment is provided to compensate for different
   average signal strengths, provision shall be made for determining the proper
   setting for the control, and if improper adjustment of the control could
   result in improper operation, a label shall be affixed at the adjustment
   control bearing a suitable warning.

   (5) The apparatus must be equipped with automatic controls that will place
   it in a non-radiating condition when no signal is being received on the
   input channel, either due to absence of a transmitted signal or failure of
   the receiving portion of the facilities used for rebroadcasting the signal
   of another station. The automatic control may include a time delay feature
   to prevent interruptions caused by fading or other momentary failures of the
   incoming signal.

   (6) The tube or tubes employed in the final radio frequency amplifier shall
   be of the appropriate power rating to provide the rated power output of the
   translator. The normal operating constants for operation at the rated power
   output shall be specified. The apparatus shall be equipped with suitable
   meters or meter jacks so that appropriate voltage and current measurements
   may be made while the apparatus is in operation.

   (7) The transmitters of over 0.001 kW peak visual power (0.002 kW when
   circularly polarized antennas are used) shall be equipped with an automatic
   keying device that will transmit the call sign of the station, in
   International Morse Code, at least once each hour during the time the
   station is in operation when operating in the translator mode retransmitting
   the programming of a TV broadcast station. However, the identification by
   Morse Code is not required if the licensee of the low power TV or TV
   translator station has an agreement with the TV broadcast station being
   rebroadcast to transmit aurally or visually the low power TV or TV
   translator station call as provided for in  Sec. 74.783. Transmission of the call
   sign can be accomplished by:

   (i) Frequency shift keying; the aural and visual carrier shift shall not be
   less than 5 kHz or greater than 25 kHz.

   (ii) Amplitude modulation of the aural carrier of at least 30% modulation.
   The audio frequency tone used shall not be within 200 hertz of the Emergency
   Broadcast System Attention Signal alerting frequencies.

   (8) Wiring, shielding, and construction shall be in accordance with accepted
   principles of good engineering practice.

   (d) Low power TV, TV translator and transmitting equipment using a
   modulation process for either program origination or rebroadcasting TV
   booster transmitting equipment using a modulation process must meet the
   following requirements:

   (1) The equipment shall meet the requirements of paragraphs (a)(1) and
   (b)(3) of  Sec. 73.687.

   (2) The stability of the equipment shall be sufficient to maintain the
   operating frequency of the aural carrier to 4.5 MHz ±1kHz above the visual
   carrier when subjected to variations in ambient temperature between 30 ° and
   +50 ° centigrade and variations in power main voltage between 85 and 115
   percent of rated power supply voltage.

   (e) Certification will be granted only upon a satisfactory showing that the
   apparatus is capable of meeting the requirements of paragraphs (c) and (d)
   of this section. The following procedures shall apply:

   (1) Any manufacturer of apparatus intended for use at low power TV, TV
   translator, or TV booster stations may request certification by following
   the procedures set forth in part 2, subpart J, of this chapter.

   (2) Low power TV, TV translator, and TV booster transmitting apparatus that
   has been certificated by the FCC will normally be authorized without
   additional measurements from the applicant or licensee.

   (3) Applications for certification of modulators to be used with existing
   certificated TV translator apparatus must include the specifications
   electrical and mechanical interconnecting requirements for the apparatus
   with which it is designed to be used.

   (4) Other rules concerning certification, including information regarding
   withdrawal of type acceptance, modification of certificated equipment and
   limitations on the findings upon which certification is based, are set forth
   in part 2, subpart J, of this chapter.

   (f) The transmitting antenna system may be designed to produce horizontal,
   vertical, or circular polarization.

   (g) Low power TV, TV translator, or TV booster stations installing new
   certificated transmitting apparatus incorporating modulating equipment need
   not make equipment performance measurements and shall so indicate on the
   station license application. Stations adding new or replacing modulating
   equipment in existing low power TV, TV translator, or TV booster station
   transmitting apparatus must have a qualified person examine the transmitting
   system after installation. This person must certify in the application for
   the station license that the transmitting equipment meets the requirements
   of paragraph (d)(1) of this section. A report of the methods, measurements,
   and results must be kept in the station records. However, stations
   installing modulating equipment solely for the limited local origination of
   signals permitted by  Sec. 74.731 need not comply with the requirements of this
   paragraph.

   [ 28 FR 13722 , Dec. 14, 1963, as amended at  33 FR 8677 , June 13, 1968;  36 FR 19592 , Oct. 8, 1971;  37 FR 25844 , Dec. 5, 1972;  41 FR 17552 , Apr. 27, 1976;
    43 FR 1951 , Jan. 13, 1978;  46 FR 35465 , July 8, 1981;  47 FR 21500 , May 18,
   1982;  47 FR 30496 , July 14, 1982;  52 FR 31404 , Aug. 20, 1987;  60 FR 55483 ,
   Nov. 1, 1995;  62 FR 26722 , May 14, 1997;  63 FR 36605 , July 7, 1998]