I live in NE Penna, and one of my favorite
nighttime MWDX's was WCCO in Minneapolis. ( 830 )

Recently, the signal is completely blocked
by a signal from Reading Pa. also broadcasting on 830.

I thought that WCCO was a "clear channel" station.

I can't hear WCCO as well as I used to, either, and I'm only about 300 miles
away in Milwaukee. It is often blocked by a Spanish-speaking station.