Virgin Radio is a label that independent company may license from the Virgin Group. As they all have the same or similar name, and there is no main "Virgin Radio", the initial broadcast depends on the specific radio you are referring to.
WSB radio is broadcast in the US state of Georgia. More specifically WSB is broadcast in Atlanta. The radio channel was first broadcast in March 1922.
KDKA
Calvin Coolidge took the office on March 4, 1925, and was the first to broadcast this event on radio.
KDKA, Pittsburgh PA
Nixon
In 1924, part of the Paris Olympics were broadcast.
1950
September 1967
1921
All services (including TV) were rebranded under the Virgin name in February 2007
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He invented the radio in december, year 1900 so his first broadcast would have been very shortly after that.