While on a summer hiatus in 1978 in New York City, he was the editor for two issues of Drugs & Paraphernalia Digest, with the former publisher of High Times magazine.
Among the many live guests were Henry Rollins as a co-host, Joey Ramone, The Circle Jerks, Huey Lewis, and the Meat Puppets.
In the summer of 1986, Jonathan moved up to Mesa, Arizona to start up alternative station KEYX 100.3 with his friend John "Johnny D" Dixon, referred to as "the key to your musical future."
"[1] In 1986, they wrote of "Virgin Vinyl": "When this colorful Sunday night waxfest was imported from Tucson this year, it slapped the lethargic Phoenix radio market right in the face.
[6] In August 2005, Jonathan L returned once again to 98 KUPD, where he hosted and programmed "The Lopsided World of L" on Saturday mornings and Sunday nights in prime time live.
In the fall of 1995, Rosen left Phoenix (and radio) to accept an opportunity to become senior editor of the long time, now defunct, music industry trade publication the Album Network.
In 2000, at a convention Album Network put on in New York city dubbed Y2K, Jonathan organized and hosted a panel of musicians to speak about everything from their careers to their personal lives in front of a packed house.
After more than six and a half years, Rosen left the Network Magazine Group in 2002 to launch his own independent record promotion company which he operated until 2005.
In the summer of that year, Rosen decided to leave Los Angeles and go back to radio, this time to do "Lopsided World Of L" at KUPD-FM in Phoenix.
Subsequent KUKQ festivals (there were two each year) included artists like Social Distortion and The Meat Puppets (1990), Mojo Nixon and Dead Milkmen (1990), and Rollins Band and The Sugarcubes (1992).
His festivals received national recognition in 1991, when MTV filmed its popular alternative music show 120 Minutes at that year's KUKQ Q-Fest, which included Front 242 and The Sisters of Mercy.
Jonathan L appeared on A Current Affair with Maury Povich in 1991, where he interviewed One Foot In The Grave, "the world’s oldest punk rock band," a group from Sun City, Arizona with members all over the age of 60.
2012 Spontaneous self spoken voice tracks in-between all songs on Grand Duchy album Let The People Speak by Black Francis of the Pixies and wife Violet Clark.
Sonic Unyon Records (Ontario, Canada) Track #1 "The Lopsided World Of L" intro to album by Jonathan L and Black Francis on Keyboard Wrote and voiced lyrics Music written by Lee Boyd (Go Satta) Plymouth, England.
Melbourne, Australia singer songwriter Leanne Kingwell, got together with International award-winning radio programmer and presenter Jonathan L from Berlin, Germany, and came up with a reboot of Sonny & Cher 1965 hit "I Got You Babe".