WBMX (FM)

1948-1949: WCFL-FM

The 104.3 allocation in Chicago was originally licensed in 1948 to the Chicago Federation of Labor, and went on the air as WCFL-FM on March 12, 1949. Though licensed for 22,000 watts,^[1] it only broadcast from 3 to 9 p.m. as a 400-watt simulcast of AM 1000 WCFL. It used an antenna on top of the building housing the studios.

In early October 1949, the Federation shut down WCFL-FM and announced that it would surrender the FM license because it saw no possibility to make money with it.^[4]

1961-1984: WJJD-FM/WJEZ

On January 2, 1961, the station signed on under the current license, as WJJD-FM.^[5] It was co-owned with AM 1160 WJJD (now WYLL) by Plough Broadcasting. At the time, WJJD was a daytimer. The two stations simulcast a country music format with WJJD-FM continuing WJJD's country sounds after sunset. Changes in FCC rules eventually led to a separate format for the FM.

By 1977, the station was known as WJEZ and had an beautiful country format, playing instrumental cover versions of popular country songs. This was not a ratings success, and by 1980, WJEZ had a more conventional country music format. In the early 1980s, the station gained competition as 99.5 WUSN also adopted a similar format. At that point, WJJD 1160 adopted an adult standards format, known as "The Music Of Your Life". In 1983, Infinity Broadcasting acquired both WJJD and WJEZ.

1984-2005: Oldies

On August 4, 1984, WJEZ dropped country and flipped to an oldies format as "Magic 104" with the call sign WJMK. The first song played on the station was "Good Morning Starshine" by Oliver.^[6] Initially, the playlist was similar to what RKO General's WFYR 103.5 was playing, except that WJMK played more 1950s and early 1960s music. WJMK initially also played 1970s and 1980s music, along with one new song every hour. By early 1985, all songs released after 1972 were dropped.

The station focused primarily on songs released between 1964-1969, with some 1950s and early 1960s music as well. In 1991, the station's moniker was changed from "Magic 104" to "Oldies 104.3." During the 1990s, WJMK only played one 1970s song every 90 minutes, mostly from the early 1970s. In 1992, another acquisition by Infinity made WUSN sister stations with WJMK. In 1996, Infinity was sold to CBS, adding classic rock station WCKG (105.9 FM), 1970s-based oldies station WYSY (107.9 FM), rhythmic/CHR WBBM-FM (96.3 FM), and adult album alternative WXRT (93.1 FM). To stay within the station ownership limits for the Chicago radio market, Infinity/CBS sold WYSY to the Spanish Broadcasting System. That move left CBS/Infinity with its limit of 8 stations; 5 FM and 3 AM stations, in addition to Channel 2 WBBM-TV.

In 1998, WJMK began to add more 1970s music to the format, cutting off at about 1975, and playing two to three 1970s oldies per hour while still playing a couple of 1950s songs an hour, as well as three to four pre-1964 oldies an hour. In 1999, with competition from the new Jammin' Oldies format of WUBT, WJMK added a few disco songs and three or four 1970s songs per hour in the mix. WJMK also added several dozen early 80's songs playing about one every 2 hours. The station cut the pre-1964 songs to about 3 an hour. WJMK also began a 1970s and early 1980s rock show on Saturday evenings, replacing a more traditional 1950s, 1960s and early 1970s oldies show.

WJMK dropped the moniker "Oldies 104.3" and returned to the former moniker "Magic 104.3," on February 8, 2002.^[7] WJMK continued with its oldies format, but reducing the pre-1964 oldies to one or two per hour. By 2003, the pre-1964 oldies were just about eliminated and WJMK now focused on 1964 to 1979 oldies. In July 2003, the station once again changed monikers, going back to "Oldies 104.3" and added some 50's and early 60's oldies back to the playlist, mixing in with the 1964-1979 hits.^[8]

WJMK also began airing Dick Bartley's syndicated "Rock and Roll's Greatest Hits" on Saturday nights. But in June 2004, WJMK returned the "Saturday Night 70s" show. By the winter of 2004-2005, all except about a dozen pre-64 oldies and most of the 1980s hits were gone. At this point, WJMK played almost entirely songs from 1964 to 1979. The station dropped the "Oldies" moniker and became known as just "104.3 WJMK".

2005-2011: Jack FM

In the early 2000s, an adult hits format known as "Jack FM" had seen success on several Canadian stations. In the spring of 2005, Infinity Broadcasting (which was changing its name to CBS Radio) contracted with SparkNet Communications, which owned the Jack trademark, to put it on several of its FM stations. That April, CBS Radio flipped KCBS-FM in Los Angeles and WQSR in Baltimore to the new format. On June 3, 2005, WJMK became "Jack FM" at the same time veteran oldies station WCBS-FM in New York City made the same switch.^[9][10][11]

The Jack FM format features mostly rock and pop songs that appeal to adults, with an occasional novelty song. It often has no live DJs and instead uses witty but sarcastic remarks voiced by Howard Cogan during breaks. The roughly 2,000 song playlist mainly consists of titles from the 1970s, 1980s, 1990s, with some 2000s songs. Though WJMK's previous oldies format continued to be streamed online and on the HD Radio subchannel, complaints about WJMK's switch were numerous, but not nearly to the extent of those in New York City with WCBS-FM.

The former WJMK DJs returned to the air on WJMK-HD2 in October 2005. Also, that fall, ABC-owned 94.7 WZZN (now WLS-FM), saw a format void in Chicago radio. After many years of struggling with different formats, it switched to the "True Oldies Channel", a satellite-delivered oldies format owned and operated by ABC and programmed by New York program director Scott Shannon. On July 13, 2006, in a cost-cutting move by CBS Radio, the entire DJ staff of WJMK-HD2 was laid off, though the oldies format continued online and on HD Radio, without air talent. WLS-FM has added several of WJMK's former airstaff.

With a format change on WCKG from hot talk to adult contemporary, Steve Dahl and Buzz Kilman moved to WJMK to host mornings. They started on November 5, 2007, as the only live personalities on Jack FM. Dahl was dismissed on December 5, 2008. At that time, Jack FM reverted to having no live personalities. WJMK saw some ratings erosion when Bonneville International debuted "Rewind 100.3" (a mostly 1980s-based format) on rival 100.3 WILV in June 2010. While Jack FM continued on several CBS Radio stations, such as KCBS-FM in Los Angeles, KJKK in Dallas and KZJK in Minneapolis, Jack FM saw poor ratings in Chicago and New York.

2011-2017: K-Hits

On March 9, 2011, CBS announced that on March 14, beginning at 1:04 p.m., WJMK would switch to a classic hits format known as "K-Hits." The Jack FM format and brand left Chicago radio.^[12] The change marked WJMK's return to an updated version of the oldies format it dropped in 2005. Station management described the format as "high energy, music intensive and locally driven."

The final song on "Jack FM" was "Goodbye to You" by Scandal, after which one last liner featuring Homer Simpson was played advertising "a new radio station coming to Chicago that just so happens to be on this frequency." A montage of songs from 1966 to 1989 was played. It was similar to what WCBS-FM did in 2007 when it relaunched its classic hits format, and using the almost exact same montage that launched the oldies format of WOCL-FM in Orlando in 2008. "K-Hits" then launched with "Beginnings" by Chicago.^[13]

Chicago radio personalities Ed Volkman and Joe "Bohannon" Colborn (Eddie and JoBo) hosted the station's morning show, along with Gary Spears in middays, Bo Reynolds in afternoon drive time and George McFly heard in the evening.

Volkman and Colborn were released on December 6, 2012, with the station citing low ratings as the main factor. Mornings were then hosted by Dave Fogel, formerly of WLS-FM. The rest of the station's final airstaff included Brian Peck in middays and Jeffrey T. Mason in afternoon drive. Weekend airstaff included Ken Cocker, John Calhoun, and Dona Mullen.

In its last year, the station played less music from the 1960s, except for a few major artists such as The Beatles, The Rolling Stones, and Creedence Clearwater Revival. WJMK focused mainly on songs from the 1980s, with a moderate amount of 1970s music, and a small amount of 1990s music.

Jingles were done by Reelworld Productions in Seattle as of 2017. JAM Creative Productions in Dallas previously did all station jingles.

2017-Present: 104.3 Jams

On February 2, 2017, CBS Radio announced it would merge with Entercom.^[14] The merger was approved on November 9, 2017, and was consummated on the 17th.^[15][16]

On that day, at 10 a.m., after playing "The Long and Winding Road" by The Beatles and "Changes" by David Bowie, WJMK began stunting with a heartbeat and other sound effects, and sound clips of a man giving occasional comments, such as "What's going on here?" and "It's almost time to start." One hour later, WJMK flipped to classic hip hop as "104.3 Jams," with an introduction by rapper and station voiceover MC Lyte. The first song on "Jams" was "Hypnotize" by The Notorious B.I.G..^[17][18][19]

Entercom applied to move the WBMX call sign to 104.3 from its sister station in Boston to match the new format. (The Boston station is now WWBX.) The WBMX call letters had previously been used by new rival 102.7 WVAZ from 1974 to 1988.^[20] The change took effect on December 4, 2017.^[21] In addition to WVAZ, WBMX also competes with WPWX and WGCI in the urban radio market. WBMX is the second station in Chicago to use the "Jams" moniker. It was originally used in the mid-1990's on 106.3 WEJM (now WSRB).

Call Letter History

From 1974 to 1998, the call letters WBMX were originally assigned in the Chicago area to 102.7, licensed to Oak Park, Illinois. (That station frequency is now home to Urban AC station WVAZ.) The call letters were then assigned to 640 AM in Zeeland, Michigan, until 1991, when they were transferred to 98.5 FM in Boston to reflect the station's "Mix" branding. On December 4, 2017, the call letters were transferred from Boston (where they had moved to 104.1 FM in 2009) to 104.3 FM in Chicago.