§  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 § 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 § 73.333 are to be used in
   conjunction with the proposed effective radiated power and antenna
   height above average terrain, as calculated pursuant to § 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 § 73.333 are to be used in conjunction
   with the proposed effective radiated power and antenna height above
   average terrain, as calculated pursuant to § 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 § 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 § 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 § 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 dBµV/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
   § 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 § 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 § 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]