Creampuff -
Do you mean the maximum range of the radar was 48nm?
That!
This -
Or do you mean the Radar controller’s range of responsibility in the sky ended at 48nm?
Was much smaller! In fact, the operator on that night was not yet qualified to rely on radar for separation. He knew how to use, and could use it to assist his situational awareness, but, he was only 'qualified' to use procedural separation for aircraft in his airspace.