Time-sharing arrangements among AM stations date back to the earliest days of broadcast regulation in the late 1920s. Especially after a massive reallocation of stations on November 11, 1928, smaller stations were forced to "double-up" by sharing time.

As directional antennas and other techniques were developed, more and more stations were able to get "their own space", so to speak. Most time-sharing arrangements are no more. However, at least two remain on the AM dial, a third one ended only in 2002, and a fourth existed in Chicago until 1997.

WIBW and KKSU in northeastern Kansas

The time-sharing arrangement between a commercial broadcaster and Kansas State University ended in November 2002. Until the 27th of the month, commercial broadcaster WIBW in Topeka shared its time, but not its transmitter, with KKSU.

KKSU, formerly KSAC, began sharing time with WIBW on November 30, 1929. More details about the history of KKSU's time-sharing arrangements are in the KKSU history at this site.

In its final incarnation, KKSU broadcast weekdays from 12:30 to 5:30 pm, with WIBW on the air at all other times. This was a slight modification of a time-sharing schedule that had been in effect since October 2, 1961.

Topeka was home to another time-sharing agreement between WREN and the University of Kansas' KFKU. When WREN left the air in 1987, the one hour daily broadcasts of KFKU also ceased because KFKU did not have a separate transmitter. KFKU programming did not resume when WREN returned to the air in 1993. There is conflicting information on whether KFKU surrendered its license after 1987 or whether the FCC deleted the license in 1997. In the meantime, WREN had moved its license from Topeka to Kansas City, Kansas, and its transmitter from Grantville, Kansas to Kansas City, Missouri.

Audio Samples:
Listen to these samples of the hand-offs between KKSU and WIBW:
» KKSU to WIBW at 5:30 pm (June 1995): MP3 » WIBW to KKSU at 12:30 pm (February 1997): MP3 » KKSU to WIBW at 5:30 pm (February 1997): MP3 » WIBW to KKSU at 12:30 pm (2002): MP3 I recorded the 1997 and 2002 samples in Lawrence, Kansas. Mark recorded the 1995 sample when he still lived in Kansas City.

Time-sharing stations in Chicago

In the Chicago area, two time-sharing situations remained until June 13, 1997. One was on 1240 kHz and the other on 1450 kHz.

1240 kHz (WCRW, WEDC, WSBC)

Until July 1996, 1240 kHz was the home of the last three-way time-sharing arrangement in the United States. WCRW, WEDC, and WSBC, all broadcasters specializing in ethnic and specialty programming, shared this frequency.

In May 1996, WSBC bought out WCRW, for a price of $762,500, as reported by the M Street Journal (July 17, 1996). In July, WSBC took over WCRW's time in addition to its own. WSBC once owned WXRT(FM) and WSCR(AM) in Chicago, which were subsequently sold to Westinghouse Broadcasting.

On June 13, 1997 at midnight, WSBC assumed control of WEDC's time as well, putting an end to the last of the original time-sharing arrangements in the United States.

WSBC and WEDC used separate transmitter sites, located within a mile of each other on the northwest side of Chicago. With the 1997 merger, WSBC also began using WEDC's transmitter on a full-time basis. The WSBC-WEDC time-sharing schedule, confirmed by listening to the stations, was:

Time Station
12:00 am - 6:00 am WEDC
6:00 am - 8:30 am WSBC
8:30 am - 10:00 am WEDC
10:00 am - 3:30 pm WSBC
3:30 pm - 5:00 pm WEDC
5:00 pm - 7:00 pm WSBC
7:00 pm - 8:00 pm WEDC
8:00 pm - 10:00 pm WSBC
10:00 pm - 11:00 pm WEDC
11:00 pm - 12:00 am WSBC

You can see that WEDC used the frequency 11 hours a day (with six of those hours in the overnight period) while WSBC had 13 hours a day of air time.

Audio Sample:
» WEDC sign-off and WSBC sign-on, 8 pm, February 10, 1997: MP3

1450 kHz (WCEV and WRLL, formerly WVON)

Licensed to Cicero, a suburb next to the southwest side of Chicago, these stations share a transmitter in the city of Chicago proper. The daytime signal covers most of Chicago, though, on some car radios, there is interference northwest of O'Hare airport caused by proximity to the 50,000-watt transmitters of WMAQ, WGN, and WBBM. At night, along the shore of Lake Michigan, the signal begins to encounter the typical class C "graveyard channel" co-channel interference at Belmont Avenue (3200 North). Similar results were obtained inland at Ashland Avenue (1600 West). I definitely couldn't hear it well at night at my Chicago location in 1997 and 1998 in Edgewater (5700 North).

Still, I managed to hear the sign-ons and sign-offs for each station when I lived in Chicago. The schedule is:

Monday-Saturday Sunday
Time Station Time Station
12:00 am - 1:00 pm WRLL 12:00 am - 5:00 am WRLL
1:00 pm - 10:00 pm WCEV 5:00 am - 10:00 pm WCEV
10:00 pm - 12:00 am WRLL 10:00 pm - 12:00 am WRLL
(On Saturdays, WCEV hands off to WRLL at 8:30 pm.)

This time-sharing arrangement was a relatively recent development. An earlier station named WVON at 1450 kHz was vacated in 1975 when it purchased a more powerful station at 1390 kHz (now WGCI). The Federal Communications Commission asked classical music broadcaster WFMT to program the frequency for a few years while it evaluated applicants for the vacated frequency. In 1978, the signal was granted to two applicants, WXOL and WCEV. WXOL changed its call letters to WVON in 1984, according to FCC records. In 2006, WVON reached an agreement with Clear Channel Communications to lease Clear Channel's expanded-band station, WRLL. The move would allow WVON to broadcast 24 hours a day. The lease also includes an option for WVON's owner to buy the channel. WVON moved its programming to 1690 kHz and expanded its schedule to 24 hours a day on September 18, 2006. The WRLL call letters moved to 1450 kHz, still sharing time with WCEV. (Thanks to Scott Fybush of fybush.com's Northeast Radio Watch for additional information and insights on the origins of this time-sharing arrangement.)

Audio Sample:
» WVON sign-off and WCEV sign-on, 1 pm, February 8, 1997: MP3
» History of WVON from WVON's web site
» WCEV

Time-sharing stations in Decorah, Iowa

Another time-sharing arrangement still exists between a commercial station and a non-commercial station in Decorah, Iowa, near the Minnesota border. Commercial station KDEC and Luther College station KWLC share time at 1240 kHz. FCC records indicate that the stations broadcast from separate transmitting sites. The KWLC web site gives the station's hours as 10 pm to 1 am on weekdays and 7:00 am to 1:00 am on weekends. KDEC's web site doesn't provide a schedule of the station's operating hours. Presumably it broadcasts when KWLC isn't on the air, but it appears likely that neither station broadcasts in the overnight hours.

FCC records indicate that KDEC had at one time tried to move to a different frequency, thereby eliminating the need to share time. An application from 1983 contains this notation:

CP CHG FREQ 1200KHZ, INCR NIGHTPOWR 1KW, CHG TL3.5 MI SW OF DECORAH ON US 52, 43 15 06 91 50 24 CHG FROM NON DA TO DA-2, GO FROM SHARE TIME OPR. TO SEPARATE FULLTIME OPR.

In English, that means the station wanted to move to 1200 kHz, increase nighttime power to 1,000 watts with a directional antenna using separate patterns day and night, and relocate its transmitting site. However, two requests in 1984 to extend the time allotted to build the proposed facility were denied by the FCC. In 1991, KDEC requested a power decrease to 580 watts and a change in transmitting coordinates, indicating that the station was moving its transmitter site. The proposal was considered a "minor change" not requiring an environmental study, unlike the 1983 proposal. It was approved July 11, 1991.

KWLC still broadcasts with 1,000 watts, indicating that it has not moved in the last couple of decades, at least.

Thanks to Joel Hermann, who posted about this arrangement in the rec.radio.broadcasting Usenet discussion group (newsgroup).