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type approval is based are set forth in Part 2, Subpart F, of this chapter.

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ton, DC: within the tolerance prescribed in E all mås$ 73.687 (b) (7) and that the visual signal

is maintained in accordance with the standarta requirements of this subpart. VB, WIE

(4) If conditions beyond the control of tional

the licensee or permittee prevent the
restoration of the monitor or monitoring
equipment to service within the period

specified above, an informal request in monitor accordance with $ 1.549 of this chapter

may be filed with the Engineer in Charge
of the radio district in which the station

is located for such additional time as En appre

may be required to complete repairs of
the defective instrument or equipment.
[28 F.R. 13660, Dec. 14, 1963, as amended at

29 F.R. 15520, Nov. 19, 1964) me that this

$ 73.692 General requirements for type

approval of frequency and modula

tion monitors.
(a) Any manufacturer desiring to
submit a monitor for type approval
shall supply the Commission with full
specification details (two sworn copies)
as well as the test data specified in
$$ 73.693 and 73.694. If this information
appears to meet the requirements of the
rules, shipping instructions will be issued
to the manufacturer. The shipping
charges to and from the Laboratory at
Laurel, Maryland, shall be paid for by
the manufacturer. Approval of a moni-
tor will only be given on the basis of the
data obtained from the sample monitor
submitted to the Commission for test.

(b) In approving a monitor upon the
basis of the tests conducted by the Labo-
ratory, the Commission merely recog-
nizes that the type of monitor has the
inherent capability of functioning in
compliance with the rules, if properly
constructed, maintained, and operated.
The Commission realizes that the fre-
quency monitor may have limited range
over which the visual indicator will de-
termine deviations. Accordingly, it is
necessary that adjunct equipment be
used to determine major deviations.

(c) Additional rules with respect to withdrawal of type approval, modification of type approved equipment and limitations on the findings upon which

§ 73.693 Requirements for type ap

proval of frequency monitors. (a) The specifications that frequency monitors shall meet before they will be approved by the Commission are as follows:

(1) The monitors shall have an accuracy of better than 500 cycles for 30 days of VHF operation, or for 10 days of UHF operation, and under ordinary conditions (ambient temperature from 10° centigrade to 40° centigrade above zero, humidity from 10 percent to 95 percent relative humidity, power supply variations from 90 percent to 110 percent, and other conditions which may affect its accuracy) encountered in television broadcast stations throughout the United States.

(2) The range of the indicating device for the aural monitor shall be at least 3000 cycles below to 3000 cycles above the assigned center frequency. Alternatively, the aural monitor may use an indicating device with a similar scale to indicate the difference-frequency between the aural and visual carriers. The range of the indicating device for the visual monitor shall be at least 1500 cycles below to 1500 cycles above the assigned carrier frequency.

(3) The scale of the indicating device shall be calibrated in divisions of not more than 100 cycles.

(4) Means shall be provided for adjustment of the monitor indication to agree with an external standard,

(5) The monitors shall be capable of continuous operation and the circuits shall be such as to permit continuous monitoring of the transmitter carrier frequencies, and the difference-frequency between the visual and aural carriers if this method of measurement is used.

(6) Operation of the monitors shall have no adverse effect on the operation of either the aural or visual transmitters or the signals emitted therefrom

and shall be independent of the fre modulation monitor is in the range requency control of the transmitters. quired for proper operations.

(7) Means shall be provided for in (2) A modulation peak indicating desuring power input level.

vice shall be provided that can be set at (8) General design, construction and any pre-determined value from 50 to 120 operation shall be in accordance with percent modulation (£25 kc/s swing is good engineering practice.

defined as 100 percent modulation) and (b) Tests to be made for approval of for either positive or negative swings television broadcast frequency monitors. (i.e., either above or below transmitter The manufacturer of a monitor shall

center frequency). submit data on the following at the time

(3) A quasi-peak indicator with a of requesting approval:

meter having the characteristics given (1) Constancy of oscillator frequency, below shall be used with a circuit such as measured daily for one month, or that peaks of modulation of duration more.

between 40 and 90 milliseconds are indi. (2) Constancy of oscillator frequency cated to 90 percent of full value and the when subject to vibration tests which

discharge rate adjusted so that the would correspond to the treatment re pointer returns from full reading to ceived in shipping, handling and in within 10 percent of zero within 500 to stalling the instrument.

800 milliseconds. A switch shall be pro(3) Accuracy of reading of the fre vided so that this meter will read either quency deviation instrument.

positive or negative swings. (4) Functioning of frequency adjust (4) When modulation of a magnitude ment device.

necessary to produce a deflection equiva(5) Effects on frequency readings, of lent to 100 percent modulation is sudthe changing of tubes, of voltage varia

denly applied and left on, the indicating tions, and of variations of room tem

instrument shall not deflect beyond 110 perature through a range from 10° to

percent on the first passage of the 100 40° C.

percent mark and shall have excursion (6) Response of indicating instru

from the final value of less than 1 perment to small changes of frequency. cent after one second or more. (7) General information on the effect

(5) The meter scale shall be similar in of tilting or tipping or other tests to

appearance to that of a standard VU determine ability of equipment to with meter. The scale length between 0 and stand shipment.

100 percent modulation markings shall (c) Various other tests may be made be at least 2.3 inches. In addition to or required, such as effects of variation other markings a small marker for 133 of input from the transmitter depend percent modulation, designated as such, ing upon the character of the apparatus. should be included for the purpose of

(d) Tests shall be conducted in such testing the transmitter with 33.3 kc/s a manner as to approximate actual oper swing. ating conditions as nearly as possible. (6) The indicated reading in percentThe equipment shall be tested on the age shall be accurate within +5 (based highest channel for which it is designed. on 100 percent modulation) at any per

centage of modulation up to 100. § 73.694 Requirements for type ap

(7) The frequency characteristic proval of aural modulation monitors.

curve as measured at 50 percent modula(a) The required aural modulation tion shall not depart from a straight monitor may or may not be a part of line more than +12 db from 50 to 15,000 the frequency monitor.

cycles Distortion shall be kept to a (b) The specifications that the aural minimum. modulation monitor shall meet before (8) The monitor shall not absorb apit will be approved by the Commission preciable power from the transmitter. are as follows:

(9) Operation of the monitor shall (1) Means shall be provided for in have no adverse effect on the operation dicating that the signal input to the of the transmitter.

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(10) General design, construction, and operation shall be in accordance with good engineering practice.

(c) Tests to be made for approval of television broadcast aural modulation monitors. The manufacturer of a monitor shall submit data on the following at the time of requesting approval:

(1) Audio frequency response of the monitor from 50 to 15,000 cycles in db from the response at 400 cycles.

(2) Distortion in the response.
(3) Input signal power required.

(4) Permissible tolerance on input signal power to keep the meter reading correct within 5 percent units.

(5) Ballistic characteristics of the monitor indicator.

(d) Various other tests may be made or required depending on the character of the apparatus.

(e) Tests shall be conducted in such a manner as to approximate actual operating conditions as nearly as possible. The equipment shall be tested on the highest channel for which it is designed.

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