The Cuban Radio Reloj network was not "jammers" but a set of stations intended to cover the 800-mile-wide island nation of Cuba. With typical bad Caribbean Basin conductivity, it took many stations and plenty of power to do that.
Going back to the 30's, Cuba thought that NARBA had screwed the by not taking into account the high population spread across that wide, wide island and the poor conductivity.
By the authorization of the Cuban government. They abrogated their participation in NARBA and with the aid of Russia in the early 60's rebuilt and reassigned many stations, creating both a number of national networks and some regional and even a number of specialized local stations. As Cuba was not under any international treaty, they could do whatever they wanted.
That use of 530 was accepted by Canada, but not the other old NARBA nations. 1700 was a general agreement by those who still respected NARBA, mostly Canada, the US and Mexico.
No. In fact, some other Latin American nations, like Costa Rica, Ecuador and Argentina started to use 530, while others did not.
Mostly, they wanted non-Cuban stations not to be heard in Cuba, particularly the Spanish language ones in Miami... and Radio Swan and Radio Martí. So they made sure that nearly every viable channel would be occupied with local stations that were part of their domestic broadcast system.
Obviously, they knew the refugees in Florida would not listen... and the non-Hispanics would not listen to Spanish language radio. So, in the 60's and 70's, most of the efforts were to build up the Russian supported socialist agenda across the country.
