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 type accepted 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 type accepted by the FCC. 
External preamplifiers also may be used provided that they do not cause 
improper

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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 type accepted 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

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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 plus-minus 
1kHz above the visual carrier when subjected to variations in ambient 
temperature between 30 deg. and +50 deg. centigrade and variations in 
power main voltage between 85 and 115 percent of rated power supply 
voltage.
    (e) Type acceptance 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 type acceptance by 
following the procedures set forth in part 2, subpart J, of this 
chapter. Equipment found to be acceptable by the FCC will be listed in 
the ``Radio Equipment List'' published by the FCC. These lists are 
available for inspection at the FCC headquarters in Washington, DC or at 
any of its field offices.
    (2) Low power TV, TV translator, and TV booster transmitting 
apparatus that has been type accepted by the FCC will normally be 
authorized without additional measurements from the applicant or 
licensee.
    (3) Applications for type acceptance of modulators to be used with 
existing type accepted 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 type acceptance, including information 
regarding withdrawal of type acceptance, modification of type accepted 
equipment and limitations on the findings upon which type acceptance 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 type accepted 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]