B717 FLC RETURN TO LAND AT JAX WHEN ENCOUNTERING RADIO COM LOSS.

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ON CLBOUT FROM JAX; RWY 7; DEP COMPLAINED OF POOR QUALITY RADIO XMISSION. THERE HAD BEEN NO PRIOR INDICATIONS OF RADIO TROUBLE. THE FO; WHO WAS THE PF; WAS ABLE TO COM CLRLY. WE WERE GIVEN A TURN TO THE NW AND A CLB TO 15000 FT. SHORTLY THEREAFTER; WE REALIZED THAT WE HAD NO COM AT ALL. WE MAINTAINED HDG AND ALT WHILE ATTEMPTING TO TROUBLESHOOT. NOT HAVING ANY SUCCESS; WE DECIDED TO RETURN TO JAX. WE SET 7600 IN THE XPONDER AND PROCEEDED BACK. BEGINNING A DSCNT AS WE APCHED THE ARPT. FOR APPROX 30 SECONDS; THE #2 RADIO WORKED AS WE APCHED JAX; AND DURING THAT TIME; WE WERE ABLE TO NOTIFY COMPANY OF OUR RETURN AND ESTABLISH THAT JAX APCH WAS AWARE OF OUR SIT AND GOT THE ACTIVE APCH AND A VECTOR TO THE DOWNWIND FOR RWY 7 ILS. COM WAS AGAIN LOST AND WE PROCEEDED ONTO THE BASE AND THEN FINAL AND AN UNEVENTFUL LNDG. I CALLED THE TWR AFTER LNDG TO THANK THEM FOR THEIR HELP AS WELL AS JAX CTR. NEITHER INDICATED ANY CONCERN ABOUT THE PROCS USED. CONTRACT MAINT FOUND BOTH COM RADIOS TO BE WITHOUT PWR. THEY WERE ABLE TO RESTORE THE RADIOS WITH A GENEROUS AMOUNT OF RE-RACKING AND SWAPPING.