I started seriously DXn AM in January 1974. All I had to help me was the Vane Jones book. (See a sample via DavidEduardo at
www.amlogbook.com --- mine was the salmon colored one from 1972-73.)
At that time, I did not understand how AM at night worked----I thought (apparently) that all AM stations were non-directional. I never could understand why, from my home in Hialeah FL, I could hear WDBF 1420 only in the day, but not at night; WRBL Columbus GA was the dominant one, but when I was vacationing with my folks near Ocala, I did manage to hear WDBF!
Then much much later, I bought the NRC AM Logbook with the night pattern maps. Then I understood more.
Today in south FL, AM at night is an absolute mess. Almost every frequency sounds like a graveyarder. I hardly bother anymore. Most of the time I restrict my AM DXn to daytime, from remote areas, just to see how far the signals go.
BTW, I did hear KNX in late 1990 from Broward County FL, but not since---not that I have tried. Also in 1988 or 89 I heard KNIX (now KMIK) near Phoenix (with WSRF off in the overnight), despite a pattern toward Australia!
cd