The western MI stations disappeared and 1660 NJ was in the clear, lots of Korean language, then exactly at 1800 EST, a tone sounded and in English the station ID:
1660 WWRU Jersey City NJ, Jan 04 1800 EST. 478 mi.
First time I ever heard a tone before the ID.
Their signal is beamed south east at 10 kw
Byron nr Detroit Mi, Sony SRF-M40W barefoot