Quote:
Originally Posted by Jeffhs
The FCC abolished clear channels about 25 years ago. The new rules now state that former clear channel stations must limit their coverage to, at most, 750 miles (directional at night if necessary), day and night. The reason for this was so that low-power local-service stations, presently daytime-only, operating on the former clear channels could serve their areas full-time if they desired (and had the money to) do so. Today, the new regulations state that former daytime-only stations operating on the former clear channels may operate full time, but they must decrease their power output by a certain level after local sundown time; as well, many stations must now use sharply directional signal patterns, attained by transmitting from one or more directional towers, separate from the station's daytime arrays. This is especially true of stations that operate 50kW during the day and were formerly licensed for dawn-to-dusk operation. If these stations go to full-time operation on a former clear channel (or any other frequency in the AM broadcast band), however, they must either reduce power to 5kW or less with a directional signal pattern after sundown or else sign off after local sundown time. A sports-talk station in Cleveland on 850 kHz recently increased its daytime power to 50kW, but must go to 4.7 kW and directional antenna after sundown Eastern time; a Detroit ESPN sports station on 1270 kHz did the same thing and operates under the same rules since it increased its power to 50kW daytime. Given the close proximity of Detroit to Cleveland, however, I cannot for the life of me see how the former's WXYT-1270 can operate 50kW during the day without interfering with Cleveland's WWMK-1260 (10kW day/5kW night); after all, the two stations are adjacent to each other on the dial. Unless there is a 5-kHz (+/-) guard band between adjacent AM frequencies, I cannot imagine these stations operating this way without one causing serious interference problems for the other in daytime, as both stations operate 50kW sunrise to sundown.  |
KMOX 1120 in St. Louis is still listed as a 50kW, non-directional station.
http://www.fcc.gov/fcc-bin/amq?list=0&facid=9638
As is WTAM on 1100.
http://www.fcc.gov/fcc-bin/amq?list=0&facid=59595
KFAX is still 50kW day and night, but is licensed for a directional antenna array.
http://www.fcc.gov/fcc-bin/amq?list=0&facid=59595
Additionally, according to the Wikipedia article on clear-channel stations, they're not prohibited from broadcasting past 750 miles, they just don't have signal protection outside that radius.
http://en.wikipedia.org/wiki/Clear-channel_station