Oh, if only it were so, AM stations would be rich! Rich, I tell you. This dates back to a 1987 article in radio world that details how AM stations receiving Cuban interference could submit to the USIA (US Information Agency), the State Department VOA oversight organization, detailed interference reports and requests for reimbursement of lost revenue. In addition to that, the FCC would consider nighttime power increases and or pattern modifications, so long as no US or Canadian station was adversely affected by the changes.
Prior to about 1980 or so, Cuba adhered to the NARBA of 1950. This allocated broadcast channels in the AM band, including clear channels for the US, Canada, Mexico, Cuba, and the Bahamas. Later on, most of the countries in South America joined the treaty and most international interference was mitigated.
Then, for reasons only known to Fidel, Cuba began broadcasting high power on several frequencies. The stations suffering the worst interference were all in Florida; WINZ, Miami, WVCG, Coral Gables, WNWS, South Miami, WEAT, West Palm Beach, WQBA, Miami, WKAT Miami Beach and WSUN, St. Petersburg.
In our neck of the woods, WICC suffered some pretty bad interference from CMKA on 600 kHz. According to the treaty, CMKA was supposed to transmit with no greater than 2.5 KW. Sometime in early 1981, they increased power to 150 KW. The path between WICC and CMKA’s transmitter site is almost entirely over salt water. Additionally, CMKA utilizes a fairly tall tower, 130 degrees according to the FCC database.
The interference was worst in the last fall and early spring. Several local newspaper articles were written about the subject, noting that WICC developed a contest around the interference. The station would drop its carrier for 10 seconds at 6:30 and 7:10 pm. Listeners would then try to identify the Cuban songs playing on CMKA and drop a postcard to WICC with that information. Winners were picked randomly from all the correct answers received (CMKA would also be heard on the studio air monitor). Coincidentally, after several months of this, the Cuban station switched its programming to English.
In any case, I believe the USIA paid out a total of $500 K to the Florida stations.