Here in Wood Dale, IL in the near NW suburb of Chicago:
Daytime: WQVU501 the TIS from Bensenville, IL being just 3/4 of a mile from me dominates the frequency. I can null it out and get weak signal from one of the five Lake County TIS's (WQBR256). Most likely the Lincolnshire one. Those get out quite well. I even had a DXer from Finland send me a recording of his catch trying to ID he station. Yes it one of the five stations that he heard. Cyberdad I would think one of those should be an easy catch in Crystal Lake.
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I finally got around to checking 1620 this morning before sunrise. Indeed, I did hear TIS on 1620. Undoubtedly one of the five from Lake County, but the signal was too weak for me to ID. I'll continue to pursue, and post anything I come up with.