COM DIFFICULTY. PLT USED PORTABLE RADIO AND RETURNED TO ARPT OF ORIGIN.

Narrative

WHILE ON AN IFR FLT TO MHT FROM BED; I ENCOUNTERED RADIO DIFFICULTIES WHEN THE AUDIO PANEL STOPPED WORKING. I CHKED THE CIRCUIT BREAKER AND THEY SEEMED TO BE IN THE NORMAL POS. ALL THE NAV EQUIP WAS WORKING AND I HAD AN ACFT HAND PORTABLE RADIO WHICH I USED TO ADVISE ATC OF THE COM PROBS. I COMPLETED THE ILS APCH AND BROKE OUT ABOVE 1800 FT MSL. I CHOSE TO RETURN TO BED RATHER THAN LAND AT MHT SINCE BED WAS VFR AS WELL AS LVM ALONG THE RTE. AT THAT POINT I REALIZED I HAD FORGOTTEN TO LIST ALTERNATES ON BOTH IFR FLT PLANS; AND I BELIEVE THERE WAS A CHANCE OF CONDITIONS BEING SUCH THAT I SHOULD HAVE LISTED ALTERNATES ON MY FLT PLANS. WHEN I LANDED AT BED; I CHKED THE AUDIO PANEL AND FOUND THE CREW HOLDING THE UNIT IN IT'S CASE HAD VIBRATED LOOSE AND ALLOWED THE UNIT TO LOSE CONTACT WITH THE CASE CONNECTORS; ETC. I REALIZED AFTER LNDG AT BED THAT I SHOULD HAVE CHKED OUT THE QUIP AT MHT AND SAVED EVERYONE A LOT OF TROUBLE. I PLAN TO STOP AND CHK OUT ANY EQUIP PROBS AS SOON AS POSSIBLE IN THE FUTURE AND TO CHK CAREFULLY FOR FORECAST CONDITIONS REQUIRING ALTERNATES TO BE LISTED ON MY IFR FLT PLANS. I TALKED TO THE CTLR AFTER THE FLT AND HE SAID THERE WAS NOT GOING TO BE ANY VIOLATION ACTION TAKEN; BUT HE SUGGESTED AND I AGREE THAT I PROBABLY COULD HAVE BEEN BETTER OFF LNDG AT MHT.