This one is hard to explain. Let's start with disambiguation. It has nothing to do with the GKB rail line, and nothing to do with Good Karma Broadcasting. This little pamphlet was published in 1938 by United Fruit just eight years after Sam Zemurray staged a hostile takeover. The pamphlet is addressed with a PO Box in Boston. It was written by James Mace Andress and Julia E. Dickson. While Dickson was also in Boston, Andress was listed as an editor at a school in Hygeia. There is no such place as Hygeia. But there was a Health and medical journal by that name which began publishing in 1923. It changed its name to "Todays Health" in 1950. Andress wrote a previous tome called "Wide Awake School" in 1931 which is probably related.
In 1901, the government of Guatemala hired the United Fruit Company to manage the country's postal service and in 1913 the United Fruit Company created the Tropical Radio and Telegraph Company. United Fruit began building a radio network. Their first station was WBF, which signed on some time before 1928. There's a great article about that here. There were a number of stations that relayed it's broadcasts: WBW, WBO, WBQ9, WCA-36, WCB-20, WCB-23, WCB-27, WNU in New Orleans wand WAX in Miami among others. But these were all maritime stations operating on marine telegraph frequencies. If the children ostensibly using this workbook were communicating with any of these stations, they were doing it in Morse code.
There was a GKB radio station and GKA. It operated out of Portishead, Bristol, UK on the Severn Estuary. But it was operated by British Telecom and had no direct connection to United Fruit. It operated from from 1928 until 2000. It even operated on single radio mast as the image on the cover indicates. But ultimately it is a child's workbook, I can only extrapolate so much. There may or may not have been a companion radio program. There may or may not have been a connection to the real GKB.
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