APCH CTLR LOSES RADAR CONTACT WITH ACR DUE TO RADAR EQUIP PROBS. ACR THEN HAS A CLOSE CALL WITH ANOTHER ACFT.

Narrative

I WAS USING NEW ASR-9 RADAR CTLING FLL APCH TFC. TFC WAS HVY. ACR X; AN MLG; WAS ON DOWNWIND IN CLOUDY CONDITIONS AT 3000 FT. I OBSERVED THE RADAR SWEEP ROTATE IN SLOW MOTION INSTEAD OF NORMAL SPD. THEN ALL COMPUTER GENERATED INFO (MODE C READOUTS; ETC) ON NON-TRACKED TARGETS DISAPPEARED. THE RADAR SWEEP RETURNED TO NORMAL SPD. BEFORE ALL THE COMPUTER GENERATED DATA RETURNED TO THE SCOPE; ACR X RPTED THAT HE WAS CLBING DUE TO A TCASII RA. AFTERWARD; THE PLT SAID WHEN HE SAW THE TFC HE WAS AT HIS ALT AND DSNDING. WHEN INFO REAPPEARED ON THE SCOPE; THE INDICATION WAS THAT THE TFC WAS SQUAWKING 1200 FT AND AT 2600 FT. THE PLT INDICATED TO ME THAT IF IT WEREN'T FOR TCASII HE MIGHT HAVE HIT HIM. THIS WAS THE SECOND TIME IN 3 DAYS THAT I PERSONALLY HAVE SEEN THE PROB WITH THE RADAR SWEEP AND LOSS OF DATA. THIS RADAR HAS PROBS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THAT THE RADAR PROBS LASTED ABOUT 2 MONTHS BEFORE BEING ISOLATED AND FIXED. THEY HAVE NOT HAD ANY PROBS SINCE THEN. RPTR THINKS THAT MAYBE XMISSION LINES ARE RESPONSIBLE FOR THE PROBS; OR CABLING. LIKES THE ASR-9 SYS; BUT NOT THE WX PRESENTATION.