Radio Nord was an offshore radio station, operating for one year in the early 1960s. While the main office was in Stockholm, the station itself was located on a ship - cargo vessel MV Bon Jour.
I guess Radio Nord that was the first Swedish offshore station traslating popular music. Equipment included 10 000 watts AM transmitters. The station was heard in Sweden, southern Finland and parts of eastern Europe.
There were own and regular Top 20 lists transmitting every month.
The station was also one of the first stations in Europe to use radio jingles. It seems to me that the jingle below was recorded by vocal ensemble The Monn-Keys.
Photos courtesy of Soundscapes (1 - testing the reception; 2 - top 20 promotion at the music records shop; 3 - top 20 list from a newspaper).
Radio Nord jingle