Sec.  73.213   Grandfathered short-spaced stations.

   (a) Stations at locations authorized prior to November 16, 1964, that did
   not meet the separation distances required by  Sec. 73.207 and have remained
   continuously short-spaced since that time may be modified or relocated with
   respect to such short-spaced stations, provided that (i) any area predicted
   to receive interference lies completely within any area currently predicted
   to receive co-channel or first-adjacent channel interference as calculated
   in accordance with paragraph (a)(1) of this section, or that (ii) a showing
   is provided pursuant to paragraph (a)(2) of this section that demonstrates
   that the public interest would be served by the proposed changes.

   (1) The F(50,50) curves in Figure 1 of  Sec. 73.333 are to be used in conjunction
   with the proposed effective radiated power and antenna height above average
   terrain, as calculated pursuant to  Sec. 73.313(c), (d)(2) and (d)(3), using data
   for as many radials as necessary, to determine the location of the desired
   (service) field strength. The F(50,10) curves in Figure 1a of  Sec. 73.333 are to
   be  used in conjunction with the proposed effective radiated power and
   antenna height above average terrain, as calculated pursuant to  Sec. 73.313(c),
   (d)(2) and (d)(3), using data for as many radials as necessary, to determine
   the  location of the undesired (interfering) field strength. Predicted
   interference  is defined to exist only for locations where the desired
   (service) field strength exceeds 0.5 mV/m (54 dBu) for a Class B station,
   0.7 mV/m (57 dBu) for a Class B1 station, and 1 mV/m (60 dBu) for any other
   class of station.

   (i) Co-channel interference is predicted to exist, for the purpose of this
   section, at all locations where the undesired (interfering station) F(50,10)
   field strength exceeds a value 20 dB below the desired (service) F(50,50)
   field strength of the station being considered (e.g., where the protected
   field strength is 60 dBu, the interfering field strength must be 40 dBu or
   more for predicted interference to exist).

   (ii) First-adjacent channel interference is predicted to exist, for the
   purpose of this section, at all locations where the undesired (interfering
   station) F(50,10) field strength exceeds a value 6 dB below the desired
   (service) F(50,50) field strength of the station being considered (e.g.,
   where the protected field strength is 60 dBu, the interfering field strength
   must be 54 dBu or more for predicted interference to exist).

   (2) For co-channel and first-adjacent channel stations, a showing that the
   public interest would be served by the changes proposed in an application
   must include exhibits demonstrating that the total area and population
   subject to co-channel or first-adjacent channel interference, caused and
   received, would be maintained or decreased. In addition, the showing must
   include exhibits demonstrating that the area and the population subject to
   co-channel or first-adjacent channel interference caused by the proposed
   facility to each short-spaced station individually is not increased. In all
   cases, the applicant must also show that any area predicted to lose service
   as a result of new co-channel or first-adjacent-channel interference has
   adequate aural service remaining. For the purpose of this section, adequate
   service is defined as 5 or more aural services (AM or FM).

   (3)  For co-channel and first-adjacent-channel stations, a copy of any
   application proposing interference caused in any areas where interference is
   not currently caused must be served upon the licensee(s) of the affected
   short-spaced station(s).

   (4)  For stations covered by this paragraph (a), there are no distance
   separation  or  interference  protection  requirements with respect to
   second-adjacent and third-adjacent channel short-spacings that have existed
   continuously since November 16, 1964.

   (b) Stations at locations authorized prior to May 17, 1989, that did not
   meet the IF separation distances required by  Sec. 73.207 and have remained
   short-spaced since that time may be modified or relocated provided that the
   overlap area of the two stations' 36 mV/m field strength contours is not
   increased.

   (c)  Short  spacings  involving  at  least  one  Class  A allotment or
   authorization. Stations that became short spaced on or after November 16,
   1964 (including stations that do not meet the minimum distance separation
   requirements  of  paragraph (c)(1) of this section and that propose to
   maintain or increase their existing distance separations) may be modified or
   relocated in accordance with paragraph (c)(1) or (c)(2) of this section,
   except that this provision does not apply to stations that became short
   spaced  by grant of applications filed after October 1, 1989, or filed
   pursuant to  Sec. 73.215. If the reference coordinates of an allotment are short
   spaced to an authorized facility or another allotment (as a result of the
   revision of  Sec. 73.207 in the Second Report and Order in MM Docket No. 88–375),
   an  application  for the allotment may be authorized, and subsequently
   modified after grant, in accordance with paragraph (c)(1) or (c)(2) of this
   section only with respect to such short spacing. No other stations will be
   authorized pursuant to these paragraphs.

   (1) Applications for authorization under requirements equivalent to those of
   prior rules. Each application for authority to operate a Class A station
   with no more than 3000 watts ERP and 100 meters antenna HAAT (or equivalent
   lower ERP and higher antenna HAAT based on a class contour distance of 24
   km)  must  specify  a transmitter site that meets the minimum distance
   separation requirements in this paragraph. Each application for authority to
   operate a Class A station with more than 3000 watts ERP (up to a maximum of
   5800 watts), but with an antenna HAAT lower than 100 meters such that the
   distance to the predicted 0.05 mV/m (34 dB µV/m) F(50,10) field strength
   contour does not exceed 98 km must specify a transmitter site that meets the
   minimum distance separation requirements in this paragraph. Each application
   for authority to operate an FM station of any class other than Class A must
   specify  a transmitter site that meets the minimum distance separation
   requirements in this paragraph with respect to Class A stations operating
   pursuant to this paragraph or paragraph (c)(2) of this section, and that
   meets the minimum distance separation requirements of  Sec. 73.207 with respect
   to all other stations.

   Minimum Distance Separation Requirements in Kilometers (miles)
   Relation Co-channel  200 kHz  400/600 kHz 10.6/10.8 MHz
   A to A     105 (65)   64 (40)     27 (17)         8 (5)
   A to B1    138 (86)   88 (55)     48 (30)        11 (6)
   A to B    163 (101)  105 (65)     69 (43)        14 (9)
   A to C3    138 (86)   84 (52)     42 (26)        11 (6)
   A to C2   163 (101)  105 (65)     55 (34)        14 (9)
   A to C1   196 (122)  129 (80)     74 (46)       21 (13)
   A to C    222 (138) 161 (100)     94 (58)       28 (17)

   (2) Applications for authorization of Class A facilities greater than 3,000
   watts ERP and 100 meters HAAT. Each application to operate a Class A station
   with  an ERP and HAAT such that the reference distance would exceed 24
   kilometers must contain an exhibit demonstrating the consent of the licensee
   of each co-channel, first, second or third adjacent channel station (for
   which  the  requirements  of   Sec. 73.207  are not met) to a grant of that
   application. Each such application must specify a transmitter site that
   meets the applicable IF-related channel distance separation requirements of
    Sec. 73.207.  Applications  that  specify  a new transmitter site which is
   short-spaced to an FM station other than another Class A station which is
   seeking  a  mutual  increase  in  facilities may be granted only if no
   alternative  fully-spaced site or less short-spaced site is available.
   Licensees of Class A stations seeking mutual increases in facilities need
   not show that a fully spaced site or less short-spaced site is available.
   Applications submitted pursuant to the provisions of this paragraph may be
   granted only if such action is consistent with the public interest.

   [ 52 FR 37789 , Oct. 9, 1987, as amended at  54 FR 14964 , Apr. 14, 1989;  54 FR 35339 , Aug. 25, 1989;  56 FR 27426 , June 14, 1991;  62 FR 50521 , Sept. 26,
   1997;  63 FR 33876 , June 22, 1998]