Complex sentence: St. Gabriel programming was previously broadcasting on WVKO (AM) 1580 kHz until the sign-on of WVSG took place... hence St. Gabriel programming on WVKO ceased on December 20 at 6:00 pm local time.
Split into simpler sentences: St. Gabriel programming was previously broadcasting on WVKO (AM) 1580 kHz until the sign-on of WVSG took place. Hence, St. Gabriel programming on WVKO ceased on December 20 at 6:00 pm local time.