Last winter I thought it was interesting to pick up a few Euro and African broadcast stations in the longwave 150-200 KHz range. But I've never heard such DX in the U.S. AM BCB. I doubt many Americans have, especially those living inland.
Have you (North Americans) ever heard intercontinental DX in the AM broadcast band? Any tips to offer as far as loudest stations and best frequencies/times?
Living inland on the West Coast, I've heard a couple stations from Japan, although not recently. One was JOUB-774khz-500KW. I also heard North Korea on a boom box (with a 4 ' spiral loop) in the mid-1980s.
My longest recent catch (not intercontinental) was a station in Mexico City, 2300 miles away, ironically on the same boom box (with a Select-A-Tenna). It was during some auroral conditions, and the "grey line" was probably also a factor.
The only tips I can give are similar to the ones the others have given: look up the frequencies of powerhouse signals overseas.
And it takes patience, lots of patience. I've monitored channels for half hours or more trying to get an ID, or at least ID a station through it's geographical comments, slogans, language, etc. And sometimes still came up with an UNID. But that's part of the fun of it.