According to Wikipedia, a Cuban radio station on 550 AM, CMBV in Wajay, has or had a 500,000 watt signal.
No, they never did and don’t now. During the peak cold war years, they had a number of 100 kw transmitter on, particularly on 1160 and 1180 to block Radio Swan and another anti_Castro program.-
Even though it is on a Regional channel for AM stations in North America, it was granted Class I-A status.
After 1960, Cuba did not take part in or observe NARBA. NARBA did not even have accurate data on Cuban stations. Like usual in this kind of radio subject, Wikipedia is totally wrong.
And CMBX, also in Wajay, runs or ran 500,000 watts on 1010 kHz, with I-A status.
No, it does not. Again, NARBA does not recognize Cuba as that country stopped notifications about 65 years ago. Cuba has never had a 500 kw station. The only 500 kw station in the Western Hemisphere is TransWorld Radio in Boniare on 800 kHz. Bonaire is not a NARBA signatory. Further, in the mid-70's there was a brief 1,000,000 station on 625 in Costa Rica called Radio Million, but it was forced to close for interfering with local communications.
Of course, these days the Cuban government doesn't report current power levels or cooperate with international radio organizations. So there's no way to know if these stations are still putting out half-a-million watts.
There is a fairly accurate list in the World Radio Handbook.
We've speculated that Cuba uses some superpower stations to cover the island.
No, they don't. They use local and regional stations all over the island to cover each zone. 500 kw would not cover the whole island given the poor conductivity anyway..
As David points out, Cuba is 750 miles wide, the distance between El Paso and Houston, Texas. So high power stations are needed to cover the island.
Again, they have nearly 150 AM stations all over the island, built by Russians and recently rebuilt by the Chinese.
Cuban AM radio stations play havoc with AM stations in Southern Florida. And sometimes when conditions are right, they interfere with stations on the East Coast of the U.S., even in New York and New England.
That is because none are directional, and are on frequencies shared with the U.S. and other nations. Some of the Miami stations put good signals over part of Cuba, but before Cuba stopped honoring NARBA, frequencies were coordinated and some of the higher powered Cuban stations were directional to protect the U.S., the Bahamas, and the Dominican Republic.
Per WRTVH, there are three 200 kw stations still, two on 710 and one on 1180. 710 has a total of 8 stations all across Cuba to block WAQI. 550 has one 12 kw station in Pinar del Río. Note that even with two 200 kw stations, Cuba need 6 more signals on 710 to cover its territory and block WAQI.
Here is the government's own list
Emisoras cubanas y frecuencias de transmisión agrupadas por provincias (AM)
This shows AM and FM by province, with links.