"An operator of radios"; which can be absolutely anyone if you think about it. Changing station on a car radio in fact makes you a radio operator.
In ye olde army Radio Operator, or RadOp, was a trade in the Royal Signals which was renamed Operator of Radios, then Communications Operator, then Radio Operator again, then Communications Systems Operator, back to Radio Operator, back to Communication Systems Operator and then... well, no-one knows what it's called now. Not even them!
Check out Radio Systems Operator for a still outdated version of the job.