WCAU didn't change anything. What did change was atmospheric conditions. These conditions, caused by a major front coming through the area, made WPVI barely receivable at my house (about 25 miles away), while WCBS-56 out of New York City was perfect (about 65 miles away) with the outside antenna aimed 180 degrees away from it.
The WPVI waveform, which is normally flat on my spectrum analyzer, had multiple notches in it, indicating multipath and signal reflections not normally present.
Things should be okay now.
Pete Putman KT2B