Clear-channel station

Clear-channel station

A clear-channel station is an AM band Radio station in North America that has the highest protection from interference from other stations, particularly concerning night-time skywave propagation. Usually known as class A stations since 1982, they are occasionally still referred to by their former classifications of class I-A, class I-B, or class I-N. The term "clear channel" is used most often in the context of North America and the Caribbean, where the concept originated.

Since 1941, these stations have been required to maintain at least 10,000 watts of power to retain their status.



Certain mediumwave frequencies were set aside under the North American Radio Broadcasting Agreement (NARBA) for nighttime use by only one or two specific AM stations, covering a wide area via skywave propagation; these frequencies were known as the clear channels, and the stations on them are thus clear-channel stations. Where only one station was assigned to a clear channel, the treaty provides that it must operate with a nominal power of 50 kilowatts or more; stations on the other clear channels, with two or more stations, must use between 10 and 50 kW, and most often use a directional antenna so as not to interfere with each other. In addition to the frequencies, the treaty also specified the specific locations where stations on this second kind of channel (known as class I-B) could be built.

Some of the original NARBA signatories, including the United States, Canada, and Mexico, have implemented bilateral agreements that supersede its terms, eliminating among other things the distinction between the two kinds of clear channel: the original "I-A", "I-B", and "I-N" station classes are now all included in class A.

Clear-channel stations, unlike all other AM stations in North America, have a secondary service area—that is, they are entitled to protection from interference to their nighttime skywave signals. Other stations are entitled, at most, to protection from nighttime interference in their primary service area—that which is covered by their groundwave signal.

Many stations beyond those listed in the treaty have been assigned to operate on a clear channel (and some had been long before NARBA came into effect in 1941). In most cases, those stations operate during the daytime only, so as not to interfere with the primary stations on those channels. Since the early 1980s, many such stations have been permitted to operate at night with such low power as to be deemed not to interfere; these stations are still considered "daytimers" and are not entitled to any protection from interference to their nighttime signals. Another group of stations, formerly known as class II stations, were licensed to operate on the former "I-B" clear channels with significant power at night, provided that they use directional antenna systems to minimize radiation towards the primary stations.[citation needed]

Clear Channel Communications, a San Antonio, Texas-based company which owns over 900 U.S. radio stations, was originally formed to purchase one clear-channel station, WOAI. The company now owns more than a dozen such stations[citation needed].


For the U.S., a form of clear channels first appeared in 1922 when the Commerce Department moved stations which had all used three (initially two) frequencies (two for entertainment stations, one for "weather and crop reports") onto 52 frequencies. Two were used for all low-power stations and the large stations each got their own frequency. A few frequencies were used on both the East and West coasts, which were considered far enough apart to limit interference. At this time large stations were limited to 1000 watts and some licences were revoked.[citation needed]

On 11 November 1928, the United States implemented General Order 40, which classified each allocation in the AM band as either Local, Regional, or Clear. The classification system considered stations in Canada as well. Gradually maximum power was increased to 50,000 watts (with some short lived experiments with 250–500 kilowatt "super-power" operation). This system was continued in the 1941 NARBA system although almost all stations shifted broadcast frequencies. The FCC's intent behind licensing 50,000 watt clear channel stations was to provide reliable radio service to the thousands of Americans who lived in the vast rural areas of the United States.[1] As a result, these stations usually reached large portions of North America at night. Radio fans often call such stations "flamethrowers" or "blowtorches" because of their power.

As early as the 1950s, debate raged in Washington, D.C., and in the U.S. broadcasting industry over whether continuation of the clear-channel system was justifiable. The licensees of clear-channel stations argued that, without their special status, many rural areas would receive no radio service at all. They requested that the power limit on the "I-A" channels in the U.S. be increased from 50 kW to 750 kW, pointing to WLW's successful experiments before the war, and in later years successful implementation by state broadcasters in Europe and the Middle East, as evidence that this would work and improve the service received by most Americans. Other broadcasters, particularly in the western states, argued to the contrary—that if the special status of the clear-channel stations were eliminated, they would be able to build new stations to provide local service to those rural "dark areas".

One station, KOB in Albuquerque, New Mexico, fought a long legal battle against the Federal Communications Commission (FCC) and New York's WABC for the right to move from a regional channel to a clear channel, 770 kHz, arguing that the New York signal was so weak in the mountain west that it served no one. KOB eventually won the argument in the late 1960s; it and several other western stations were allowed to move to eastern clear channels. (Western clear channels, like 680 in San Francisco, California, had been "duplicated" in the eastern states for many years.) These new class II-A assignments (in places like Boise, Idaho; Las Vegas and Reno, Nevada; Lexington, Nebraska; Casper, Wyoming; Kalispell, Montana; and others) began what would later be called "the breakdown of the clear channels". The class I-A station owners' proposal to increase power fifteenfold was not immediately quashed, but the new II-A stations would make it effectively impossible for stations on the duplicated channels to do so, and the owners eventually lost interest. That proposal was finally taken off the FCC's docket in the late 1970s.[citation needed]

On May 29, 1980, the FCC voted to limit the protection for the twenty-five clear channel stations to a 750-mile radius around the transmitter. Those stations outside the area of protection were no longer required to sign off or power down after sundown.[2]

In 1987 the FCC changed its rules to prohibit applications for new "class-D" stations. (Class-D stations have night power between zero and 250 watts, and frequently operate on clear channels.) However, any existing station could voluntarily relinquish nighttime authority, thereby becoming a class-D, and several have done so since the rule change.


Daytimers are AM radio stations that are limited to broadcasting during the daytime only, as their signals would interfere with clear channel and other radio stations at night, when solar radiation is reduced, and medium wave radio signals can propagate much farther. Such stations are usually supposed to do one of three things: sign off, reduce power (sometimes dramatically, to only a few watts), or switch to another (typically near-by) frequency.[citation needed] Their broadcast class is Class D.

List of all clear-channel stations

The following two tables show all of the class-A stations in North America. First is the Canada, Mexico, and contiguous United States table, for the former class I-A and class I-B stations. Second is the Alaska table, for the former class I-N stations.

Class A (former I-A/I-B) stations
Callsign City of license
540 CBK Watrous, Saskatchewan
540 CBT Grand Falls, Newfoundland and Labrador
540 XEWA San Luis Potosí, San Luis Potosí
640 CBN St. John's, Newfoundland and Labrador
640 KFI Los Angeles, California
650 WSM Nashville, Tennessee
660 WFAN New York, New York
670 WSCR Chicago, Illinois
680 KNBR San Francisco, California
690 silent[3] Montreal, Quebec
690 XEWW Tijuana, Baja California
700 WLW Cincinnati, Ohio
710 KIRO Seattle, Washington
710 WOR New York, New York
720 WGN Chicago, Illinois
730 CKAC Montreal, Quebec
730 XEX Mexico City, D.F.
740 CFZM[4] Toronto, Ontario
750 WSB Atlanta, Georgia
760 WJR Detroit, Michigan
770 WABC New York, New York
780 WBBM Chicago, Illinois
800 XEROK Ciudad Juárez, Chihuahua
810 KGO San Francisco, California
810 WGY Schenectady, New York
820 WBAP Fort Worth, Texas
830 WCCO Minneapolis, Minnesota
840 WHAS Louisville, Kentucky
850 KOA Denver, Colorado
850 XETQ Ixhuatlancillo, Veracruz
860 CJBC Toronto, Ontario
870 WWL New Orleans, Louisiana
880 WCBS New York, New York
890 WLS Chicago, Illinois
900 XEW Mexico City, D.F.
940 silent[5] Montreal, Quebec
940 XEQ Mexico City, D.F.
990 CBW Winnipeg, Manitoba
990 CBY Corner Brook, Newfoundland and Labrador
1000 KOMO Seattle, Washington
1000 WMVP Chicago, Illinois
1000 XEOY Mexico City, D.F.
1010 CBR Calgary, Alberta
1010 CFRB Toronto, Ontario
1020 KDKA Pittsburgh, Pennsylvania
1030 WBZ Boston, Massachusetts
1040 WHO Des Moines, Iowa
1050 XEG Monterrey, Nuevo León
1060 KYW Philadelphia, Pennsylvania
1060 XEEP Mexico City, D.F.
1070 silent[6] Moncton, New Brunswick
1070 KNX Los Angeles, California
1080 WTIC Hartford, Connecticut
1080 KRLD Dallas, Texas
1090 KAAY Little Rock, Arkansas
1090 WBAL Baltimore, Maryland
1090 XEPRS Rancho del Mar, Rosarito, Baja California
1100 WTAM Cleveland, Ohio
1110 KFAB Omaha, Nebraska
1110 WBT Charlotte, North Carolina
1120 KMOX St. Louis, Missouri
1130 CKWX Vancouver, British Columbia
1130 KWKH Shreveport, Louisiana
1130 WBBR New York, New York
1140 WRVA Richmond, Virginia
1140 XEMR Monterrey, Nuevo León
1160 KSL Salt Lake City, Utah
1170 KFAQ Tulsa, Oklahoma
1170 WWVA Wheeling, West Virginia
1180 WHAM Rochester, New York
1190 KEX Portland, Oregon
1190 XEWK Guadalajara, Jalisco
1200 WOAI San Antonio, Texas
1210 WPHT Philadelphia, Pennsylvania
1220 XEB Mexico City, D.F.
1500 KSTP Saint Paul, Minnesota
1500 WFED Washington, D.C.
1510 WLAC Nashville, Tennessee
1520 KOKC Oklahoma City, Oklahoma
1520 WWKB Buffalo, New York
1530 KFBK Sacramento, California
1530 WCKY Cincinnati, Ohio
1540 KXEL Waterloo, Iowa
1540 ZNS-1 Nassau, Bahamas
1550 CBE Windsor, Ontario
1550 XERUV Xalapa, Veracruz
1560 KNZR[7] Bakersfield, California
1560 WQEW New York, New York
1570 XERF Ciudad Acuña, Coahuila
1580 CKDO[8] Oshawa, Ontario
Alaskan class A (former class I-N) stations
Callsign City of license
640 KYUK Bethel
650 KENI Anchorage
660 KFAR Fairbanks
670 KDLG Dillingham
680 KBRW Barrow
700 KBYR Anchorage
720 KOTZ Kotzebue
750 KFQD Anchorage
770 KCHU Valdez
780 KNOM Nome
820 KCBF Fairbanks
850 KICY Nome
890 KBBI Homer
1020 KOAN Eagle River
1080 KUDO Anchorage
1170 KJNP North Pole

List of former clear-channel stations

Callsign City of license Fate
1190 WOWO Fort Wayne, Indiana Downgraded to class B in 1998 by reducing night power to 9.8 kW
1510 KGA Spokane, Washington Downgraded to class B in 2011 to make room for co-channel sister station KSFN, Piedmont, California, reducing night power to 15 kW[9]


  1. ^ Rural Radio Magazine, Vol. 1 No. 1, Clear Channel Group (November 1938), p. 2
  2. ^ Facts on File 1980 Yearbook, p519
  3. ^ 690 kHz at Montreal was originally assigned under NARBA to CBF, and was later reused by CINF; while now silent, it remains notified to the U.S. as a class-A allotment.
  4. ^ 740 kHz was used by CBC Radio One's CBL in Toronto until 2000 when the station moved to 99.1 FM. CFZM, known at the time as CHWO, acquired 740 in 2001.
  5. ^ 940 kHz at Montreal was originally assigned under NARBA to CBM, and was later reused by CINW; while now silent, it remains notified to the U.S. as a class-A allotment.
  6. ^ 1070 kHz was formerly used by CBA, which moved to FM in April, 2008. Canada has not withdrawn the international notification for CBA.
  7. ^ KNZR is the only U.S. class-A station licensed to operate with less than 50 kilowatts full-time; KNZR is licensed for 25 kW during the day and 10 kW at night.
  8. ^ 1580 kHz was originally used by CBJ in Chicoutimi, Quebec. After that station moved to FM in 1999, CHUC applied for and was granted 1580 kHz in Cobourg, Ontario with 10 kW, but chose instead to move to FM itself (despite being notified to the U.S. as an existing station on 1580). CKDO moved from 1350 to 1580 kHz on August 13, 2006 and became that day a class A station using 10 kW. U.S. FCC record is at [1]
  9. ^ FCC license BL-20100527AGH

See also

External links

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Clear Channel — Communications, Inc. Unternehmensform Incorporated ISIN US18451C1099 Gründung …   Deutsch Wikipedia

  • Clear Channel Communications — Clear Channel Communications, Inc. Rechtsform Incorporated ISIN US18451C1099 …   Deutsch Wikipedia

  • Clear Channel Broadcasting Tower Redfield — is a tall guyed mast located at Redfield, Arkansas, USA at 34°26′31″N 92°13′4″W / 34.44194°N 92.21778°W / 34.44194; 92.21778. Cle …   Wikipedia

  • Clear Channel UK — is a division of Clear Channel International (CCI), part of Clear Channel Outdoor based in the United States. Clear Channel Outdoor (CCO) is the world’s leading out of home advertising company with operations in 44 countries. CCO is 89% owned by… …   Wikipedia

  • clear channel — clear channel, adj. Radio. 1. a radio broadcast channel cleared for long distance broadcasting during nighttime hours. 2. a broadcast channel free of undesirable interference. * * * clear channel, a radio frequency reserved for use by one station …   Useful english dictionary

  • Clear Channel Communications — Not to be confused with clear channel radio stations, a type of AM radio station. This article is about the broadcasting company. For other uses, see Clear channel. CC Media Holdings, Inc. Type Private Industry …   Wikipedia

  • List of shows syndicated by Clear Channel — The majority of Clear Channel s syndicated talk and music shows are done through its subsidiary, Premiere Radio Networks. Premiere is a dedicated syndication company that houses dozens of talents, with a marketing division that aggressively sells …   Wikipedia

  • List of broadcast stations owned by Clear Channel — The following is a list of radio stations currently owned by Clear Channel Communications. Of these stations, 448 of the stations which are outside the Top 100 DMA markets, plus another 91 stations which may or may not be in the top 100 DMAs are… …   Wikipedia

  • Station identification — (sometimes called a sounder or stinger ) is the practice of any type of radio or television station or network identifying itself, typically with a call sign or brand name. Over the air transmitters may be required to identify themselves… …   Wikipedia

  • Channel Islands National Park — IUCN Category II (National Park) …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.