§  2.1055   Measurements required: Frequency stability.

   (a) The frequency stability shall be measured with variation of ambient
   temperature as follows:

   (1) From −30° to + 50° centigrade for all equipment except that
   specified in paragraphs (a) (2) and (3) of this section.

   (2) From −20° to + 50° centigrade for equipment to be licensed for use
   in the Maritime Services under part 80 of this chapter, except for
   Class A, B, and S Emergency Position Indicating Radiobeacons (EPIRBS),
   and equipment to be licensed for use above 952 MHz at operational fixed
   stations in all services, stations in the Local Television Transmission
   Service and Point-to-Point Microwave Radio Service under part 21 of
   this chapter, equipment licensed for use aboard aircraft in the
   Aviation Services under part 87 of this chapter, and equipment
   authorized for use in the Family Radio Service under part 95 of this
   chapter.

   (3) From 0° to + 50° centigrade for equipment to be licensed for use in
   the Radio Broadcast Services under part 73 of this chapter.

   (b) Frequency measurements shall be made at the extremes of the
   specified temperature range and at intervals of not more than 10°
   centigrade through the range. A period of time sufficient to stabilize
   all of the components of the oscillator circuit at each temperature
   level shall be allowed prior to frequency measurement. The short term
   transient effects on the frequency of the transmitter due to keying
   (except for broadcast transmitters) and any heating element cycling
   normally occurring at each ambient temperature level also shall be
   shown. Only the portion or portions of the transmitter containing the
   frequency determining and stabilizing circuitry need be subjected to
   the temperature variation test.

   (c) In addition to all other requirements of this section, the
   following information is required for equipment incorporating heater
   type crystal oscillators to be used in mobile stations, for which type
   acceptance is first requested after March 25, 1974, except for battery
   powered, hand carried, portable equipment having less than 3 watts mean
   output power.

   (1) Measurement data showing variation in transmitter output frequency
   from a cold start and the elapsed time necessary for the frequency to
   stabilize within the applicable tolerance. Tests shall be made after
   temperature stabilization at each of the ambient temperature levels;
   the lower temperature limit, 0° centigrade and + 30° centigrade with no
   primary power applied.

   (2) Beginning at each temperature level specified in paragraph (c)(1)
   of this section, the frequency shall be measured within one minute
   after application of primary power to the transmitter and at intervals
   of no more than one minute thereafter until ten minutes have elapsed or
   until sufficient measurements are obtained to indicate clearly that the
   frequency has stabilized within the applicable tolerance, whichever
   time period is greater. During each test, the ambient temperature shall
   not be allowed to rise more than 10° centigrade above the respective
   beginning ambient temperature level.

   (3) The elapsed time necessary for the frequency to stabilize within
   the applicable tolerance from each beginning ambient temperature level
   as determined from the tests specified in this paragraph shall be
   specified in the instruction book for the transmitter furnished to the
   user.

   (4) When it is impracticable to subject the complete transmitter to
   this test because of its physical dimensions or power rating, only its
   frequency determining and stabilizing portions need be tested.

   (d) The frequency stability shall be measured with variation of primary
   supply voltage as follows:

   (1) Vary primary supply voltage from 85 to 115 percent of the nominal
   value for other than hand carried battery equipment.

   (2) For hand carried, battery powered equipment, reduce primary supply
   voltage to the battery operating end point which shall be specified by
   the manufacturer.

   (3) The supply voltage shall be measured at the input to the cable
   normally provided with the equipment, or at the power supply terminals
   if cables are not normally provided. Effects on frequency of
   transmitter keying (except for broadcast transmitters) and any heating
   element cycling at the nominal supply voltage and at each extreme also
   shall be shown.

   (e) When deemed necessary, the Commission may require tests of
   frequency stability under conditions in addition to those specifically
   set out in paragraphs (a), (b), (c), and (d) of this section. (For
   example measurements showing the effect of proximity to large metal
   objects, or of various types of antennas, may be required for portable
   equipment.)

   [ 39 FR 5919 , Feb. 14, 1974, as amended at  51 FR 31304 , Sept. 2, 1986;
    56 FR 11682 , Mar. 20, 1991. Redesignated at  63 FR 36599 , July 7, 1998.
    68 FR 68545 , Dec. 9, 2003]