|City of license||La Porte, Texas|
|Broadcast area||Greater Houston/Golden Triangle|
|First air date||2005 (on current tower)|
|Callsign meaning||K Houston JacK (former format)|
|Former callsigns||KTDD (1990-1991)
|Former frequencies||97.5 MHz|
|Owner||Educational Media Foundation|
KHJK (103.7 FM, "Air 1") is a Christian rock-formatted radio station serving the Houston and Beaumont, Texas, areas. It relays the satellite delivered Air 1 format by owner Educational Media Foundation.
KHJK-FM previously operated as KVST, "K-Star Country 103.7", which was licensed to service the area north of Houston. Owned by Ben Amato of Conroe (who sold his chain of grocery stores around that area to finance the radio station), it originally signed on as KVST in Huntsville, TX on 103.5; however, interference from 103.5 in Buda, TX (Oldies 103.5 Austin, now BOB-FM) caused the station not to reach down to the intended audience of Conroe and a look at a move in frequency was done. It moved to 103.7 and later a simulcast on 99.7 (KUST, Willis) was added to help the coverage in Conroe and The Woodlands. The station, whose signal was poor in comparison to Houston's other country music stations, was purchased by Cumulus Media in mid-2004, which later acquired greater Houston's only Top 40 station, KRBE, in addition to also owning 97.5, the former KAYD-FM (now KFNC and a rimshot for Houston).
In 2005, the station's transmitter was moved to its current location in Devers to service the Houston area. This resulted in another format change, with the station switching to KIOL and its heritage rock format that had been carried on the 97.5 frequency, which was a carry over from the original heritage rock frequency of 101.1 KLOL, which had flipped to a Spanish format. 97.5 continued as a simulcast on the latter until switching to a news (and later, ESPN) sports format.
On August 30, 2007, the Houston Chronicle reported that KIOL would be switching to the Jack FM format at 10:37 a.m. the following day, and adopting new call letters, KHJK . The final songs on "Rock 103.7" were "Mary Jane's Last Dance by Tom Petty, "Cold As Ice" by Foreigner, and "Fire" by Jimi Hendrix, while the first two songs on "Jack" were "Jumpin' Jack Flash" by The Rolling Stones" and "Let's Go Crazy" by Prince."
On May 6, 2009, KHJK shifted from adult hits to adult alternative as "103-7FM." 
As part of a prepackaged bankruptcy filing, the lenders took over the license of four Cumulus Media Partners stations; two in the Kansas City metro area (KCHZ and KMJK) and the two rimshot signals in the Houston metro, KHJK and KFNC in November 2011. Station broker Larry Patrick became majority owner and set out to sell the stations to recover the value for the lenders. After the filing, Cumulus continued to program the stations under LMA. While Cumulus could have purchased the stations back, the highest bidder for KFNC was David Gow, owner of KGOW (1560 The Game) and the highest bidder for KHJK was Educational Media Foundation, who programs Christian AC and Christian Rock formats.
Between In The End and Closing Time, the announcer gave this goodbye message :
"Houston, thank you. It's been an amazing ride. Steve, Donna, and the entire 103-7FM crew want to say thanks for being there for us. Attending our events, coming to our shows, and just for listening to Houston's adult alternative, 103-7FM. It's been our pleasure serving you some of the best new music out there and playing music you can't hear anywhere else but 103-7FM. You are some of the best listeners we could have ever asked for, and we'll miss you. Thanks again. And are you hiring?"
- KTDD - 05/03/1990
- KVST - 07/22/1991 (K-Star Country)
- KUST - 03/30/2005
- KIOL - 05/23/2005 (Rock 103-7)
- KHJK - 09/01/2007 (103.7 Jack FM, 103-7 FM, Air-1)
Cumulus Broadcasting began upgrading its stations to HD Radio broadcasting in 2005. One of the first ten stations to be upgraded was KIOL. The station had been simulcast on KRBE HD-2, but this was replaced by a feed of the True Oldies Channel in June 2012.
- Harnett, Mary Beth (2006-04-24). "Harris Corporation Announces Multi-Deal Agreement as Exclusive HD Radio(TM) Supplier to Cumulus Broadcasting". EE Times.
- 103.7 changes format on Houston Chronicle 29-25
- Query the FCC's FM station database for KHJK
- Radio-Locator information on KHJK
- Query Nielsen Audio's FM station database for KHJK