A C172 COMMERCIAL PLT LANDS AT VERO BEACH WITHOUT RADIO CONTACT AFTER EXPERIENCING A PRIMARY ELECTRICAL SUPPLY PROB W OF VRB; FL.

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WHILE HOLDING AT BUEYE INTXN AT 2500 FT MSL WAS IN CONTACT WITH ZMA WAITING FOR CLRNC FOR VOR RWY 11R APCH TO VERO BEACH. XPONDER FAILED AND ZMA; AFTER TRYING TO HAVE ME RESET XPONDER WITHOUT SUCCESS; HAD ME CHANGE SQUAWK TO 1200. THEN ADF BEGAN TO BLINK; ALL GAUGES WENT TO ZERO. LOUD BUZZING NOISE STARTED THAT WOULD NOT STOP; RADIOS FAILED. AMMETER SHOWED NORMAL; ALL CIRCUIT BREAKERS IN. I COULD SMELL SMOKE AND FEARED ELECTRICAL FAILURE/FIRE DUE TO SMELL AND LOUD NOISE (ELECTRICAL SHORT?) THERE WERE 2 UNCTLED FIELDS NEARBY; X26 AND X52; BUT SINCE BY THIS TIME I HAD SHUT OFF MASTER I DIDN'T WANT TO GO TO X26 (PARACHUTE JUMPING WAS IN PROGRESS) ONLY TO FIND X52 (A GRASS STRIP) BUT RATHER TO LAND ASAP. ALSO PRESUMED VRB HAD EMER SVCS. I DSNDED TO 1000 FT AND ENTERED L DOWNWIND FOR RWY 4. TRIED TO CONTACT TWR USING HAND-HELD AND DECLARE MAYDAY BUT COULD NOT CONTACT TWR. FLEW PATTERN; LANDED RWY 4; AND AFTER SHUTDOWN CALLED TWR TO EXPLAIN WHAT HAPPENED. SUBSEQUENT INSPECTION REVEALED NO FIRE; JUST ALTERNATOR FAILURE AND DEAD BATTERY. IF I HAD KNOWN THAT; I WOULD HAVE FLOWN NORDO TO X52 BUT GIVEN MY CONCERN OF FIRE AT THE TIME I THINK I DID THE BEST THING. I ALSO PUT NEW BATTERIES IN THE HAND-HELD. NOT MUCH HELP WHEN THE BATTERIES ARE WEAK.