(f) Stations on 1580, 1590 and 1600 kHz. In addition to the rules governing the authorization of facilities in the 535-1605 kHz band, stations on these frequencies seeking facilities modifications must protect assignments in the 1610-1700 kHz band. Such protection shall be afforded in a manner which considers the spacings that occur or exist between the subject station and a station within the range 1605-1700 kHz. The spacings are the same as those specified for stations in the frequency band 1610-1700 kHz or the current separation distance, whichever is greater. Modifications that would result in a spacing or spacings that fails to meet any of the separations must include a showing that appropriate adjustment has been made to the radiated signal which effectively results in a site-to-site radiation that is equivalent to the radiation of a station with standard Model I facilities (10 kW-D, 1 kW-N, non-DA, 90 degree antenna ht. & ground system) operating in compliance with all of the above separation distances. In those cases where that radiation equivalence value is already exceeded, a station may continue to maintain, but not increase beyond that level. Note 1: In the case of applications for changes in the facilities of AM broadcast stations covered by this section, an application will be accepted even though overlap of field strength contours as mentioned in this section would occur with another station in an area where such overlap does not already exist, if:
(1) The total area of overlap with that station would not be increased;(2) There would be no net increase in the area of overlap with any other station; and(3) There would be created no area of overlap with any station with which overlap does not now exist.Note 2: The provisions of this section concerning prohibited overlap of field strength contours will not apply where:
(1) The area of overlap lies entirely over sea water: or(2) The only overlap involved would be that caused to a foreign station, in which case the provisions of the applicable international agreement, as identified in § 73.1650 , will apply. When overlap would be received from a foreign station, the provisions of this section will apply, except where there would be overlap with a foreign station with a frequency separation of 20 kHz, in which case the provisions of the international agreement will apply in lieu of this section.Note 3: In determining the number of "authorized" aural transmission facilities in a given community, applications for that community in hearing or otherwise having protected status under specified "cut-off" procedures shall be considered as existing stations. In the event that there are two or more mutually exclusive protected applications seeking authorization for the proposed community it will be assumed that only one is "authorized."
Note 4: A "transmission facility" for a community is a station licensed to the community. Such a station provides a "transmission service" for that community.