Does availability of the SRA depend on the make and model of the radar, to any degree ? I believe the old Decca 424 and the Plessey 430 were geared as both general airfield radars as well as the SRA facility whereas the likes of the Marconi 264 weren't suitable for the job; something to do with the big blips, probably. I've never worked in ATC so please indulge any misunderstandings.
I don't know if the latest Raytheon, Thales etc. radars are approved for SRAs.