LOS COM BY ACR HVT ON A DAWN APCH TO ORD.

Narrative

FO FLYING AND CAPT HANDLING RADIOS. ZAU CLRED ACFT TO 11000 FT; ESTABLISHED ON THE LOC RWY 32L AT ORD. ATTEMPTING TO GET LOWER AND GOT NO ANSWER ON RADIO. CAPT ATTEMPTED CALLS ON CTR; APCH; TWR; GND AND EMER FREQS. FO AND FE ALSO ATTEMPTED CALLS ON THEIR PANELS WITHOUT SUCCESS. '7600' WAS SQUAWKED AND DSCNT ON THE LOC TO RWY 32L WAS INITIATED. ON APPROX 6 MI FINAL; WE SAW AN ACFT BEACON AHEAD APPROX 2-3 MI. NOT KNOWING THE SPD OF THIS ACFT WE INITIATED A L 360 DEG TURN. THE CAPT CONTINUED CALLING IN THE BLIND TO ORD APCH ON 121.5. 1/2 WAY THROUGH THE 360 DEG TURN WE SAW ANOTHER ACFT AND STOPPED THE TURN PARALLELING THIS ACFT. AT THIS TIME THE CAPT CALLED AGAIN AND WE HEARD ORD APCH ANSWER AND TOLD US TO MAINTAIN A VISUAL ON THIS ACFT. APCH THEN SAID THE ACFT ON FINAL WAS GOING AROUND AND WE WERE CLRED TO LAND. AFTER LNDG; OUR RADIOS ALL WENT DEAD AGAIN. WE RECEIVED LIGHT SIGNALS FROM THE TWR AND TAXIED TO OUR RAMP. MAINT FOUND A MICROPHONE THAT HADN'T BEEN USED HAD SOMEHOW BECOME DEFECTIVE AND CAUSED THE CREW FROM HEARING INBOUND CALLS. A MISSED APCH PROC WE BELIEVED WOULD PUT US OVER TOP OF THE ACFT IN FRONT OF US OR A DEPARTING ACFT FROM ANOTHER RWY; AND MIX US INTO OTHER ARRIVING ACFT; CREATING A MUCH MORE SERIOUS PROB THAN A 360 DEG TURN TO ALLOW SEPARATION BTWN US AND THE ACFT IN FRONT OF US.