Hey Yankee,
My jaw dropped when I saw you post K and X call signs, until I read that you are currently out on "the coast"

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Nice catch to hear the Border Blaster "Express" / XEPRS , one of my favorites that I've read about re the old Mexican Flame Throwers.
I have never heard a Mexican on MW from MA. PLENTY of Cubans and some other Caribbeans (especially when I am in the town of Gosnold on Cuttyhunk Island , Buzzards Bay , MA ) but never a peep on MW. Just too much of stretch - WAY too much U.S. on frequency on same bearing .
I've only ever copied Mexico on HF . Even then, at least in my experience at my station, it was exceedingly rare over the years for some reason. Maybe 1 or 2 hams and 1 or 2 broadcasts over 50 years.That's it.
I heard a LOT more from the "tough" areas of South America than from old Mexico.
TONS of night time Mexicans crystal set copied while I was on the Gulf coast of FL, EASY "fish in the barrel" type of catches. Even some in daytime on car radio.No brainer there.
But to me ANY Mexican copy, even when you are "staring" at it (ie from West FL) is AWESOME !
OT, but speaking of Mexicans, one of my favorite pirates was XEROX, "Radio Duplicado". Hilarious !
K