Yes,it was WRKO and,yes,you're partially correct on the fadeout issue.In a nutshell the fadeout issue goes like this...between sundown and sunup WRKO is required to reduce their power as are,IIRC,many other AM stations.My understanding is that during this reduced power broadcasting their signal still comes in gangbusters north and south of the city.It's my understanding that RKO comes in gangbusters at night in Maine and on Cape Cod.The problem is that the most heavily populated suburbs of Boston are located *west* of the city.For me,being not too far west of Boston (certainly a lot closer than is Maine),RKO is useless to me after sundown.But I listen on the internet so it isn't an issue with me.Also,he's syndicated on a number of New England stations including one in Central Massachusetts.
Yes and in addition near sunset in some places like where I am in Beverly (E of the antenna in Burlington) yeah it comes in OK but you hear the other stations mixing with it in the background. Especially this time of year.
Yet, in my home state, CT, WTIC AM stays high power, 50,000 wattage, flamethrower power station, all the time, 24/7. Maybe only when fromt time to time, during the spring/summer, when their tower has to be worked on, say on a Saturday or Sunday night, going into the overnight, and thus they annouce it as well, they go off for a couple of hours. But that is it.