Looking for more information about the earliest days of television and FM in Indianapolis, it occurred to me that newspaper archives would be a great source; after all, the city has had some great newspapers: the Indianapolis Times (d., 1965), the Indianapolis News (b., 1869 - d., 1999, after a long illness; survived for a short while by Herman Hoglebogle) and the Indianapolis Star; two of those papers even owned radio stations, so there must be plenty of news about local radio to be found.
Possibly there is, but not online from those sources; the "morgue" files of the Times and the News appear nowhere and the Star has a gap from 31 December 1922 to 21 May 1991.
One newspaper has extensive archives, wonderfully searchable, compiled by IUPUI: the Indianapolis Recorder, which has served the city's African-American community since its inception in 1895. And on 13 July 1946, WABW shows up, in an ad for a song to be broadcast on the 17th of that month at 5:30 p.m.. This was a standalone FM, in a time when few FM radios were available, so it's especially interesting to note the ad doesn't list the frequency.
After the ownership and call letter change, WXLW and (simulcast) WXLW-FM schedules and coverage show up frequently in The Recorder: WXLW had no network affiliation and a policy of not running drama or "chat" shows. They block-programmed many kinds of music, including programs aimed at the the paper's readership. (But, as a 1948 article puts it, not "hot jazz or drum solo type of so-called music." It was another time and the front-page headlines make for sobering reading.) Published schedules make clear that the FM kept running until late at night, long after the AM shutdown at sunset.
At least there's one newspaper in Indianapolis with a sense of history. Thank you, Recorder.