GA SMT MISDIALED TWR FREQ THOUGHT RADIO FAILURE AND ENTERED ATA WITHOUT CLRNC. POTENTIAL WITH GA SMA ON FINAL.

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TRANSITIONING FROM MIAMI CENTER TO UNICOM (ON VFR FLT PLAN WITH RADAR ADVISORIES) THEN TO TWR; TRANSPOSED FREQS. THOUGHT THAT OUR RADIO WAS INOP. ENTERED DOWNWIND FOR RWY 14 FT PIERCE. DSNDED FROM 1500' INTO TFC FLOW. ON SHORT FINAL RECEIVED GREEN LIGHT FROM TWR; HOWEVER; SAW AN SMA ABOVE ME BREAK OFF APCH. IF I HAD BEEN MORE FAMILIAR WITH RADIOS; AREA; ETC.; WOULD HAVE BEEN NO PROB. SEVERAL FACTORS CONTRIBUTED TO PROB: 2ND TIME IN THIS PARTICULAR ACFT; NEW TWR AT FT PIERCE; MIAMI CENTER DID NOT HAND ME OFF TO FT PIERCE TWR; AS I SAW THE ARPT AT 20 MI; I CALLED ARPT IN SIGHT. NEXT CALL WAS TO UNICOM; THEN TO WHAT I THOUGHT WAS TWR FREQ. SHOULD HAVE CIRCLED ARPT AT A HIGHER ALT. THEN DSNDED INTO TFC FLOW. PROCS SHOULD BE REVIEWED FOR RADIO FAILURE INTO CTL TWR ARPTS; ESPECIALLY ONES THAT ARE POINTS OF ENTRY. CALLBACK CONVERSATION WITH RPTR REVEALED FOLLOWING INFO. INCIDENT REVIEWED WITH TWR AFTER RPTR CLRED CUSTOMS AND EXPLAINED TO THEM HE HAD TRANSPOSED TWR FREQ AND THOUGHT HE HAD A RADIO FAILURE. DID FLY DOWNWIND WITH GEAR DOWN AND LIGHTS ON AND GREEN LIGHT ON FINAL WAS FOR HIM. ESTIMATED CLOSEST TO SMA WAS 500'; BUT THINKS SMA WAS IN CONTACT WITH TWR AND WAS GIVEN A GO AROUND RATHER THAN TAKING EVASIVE ACTION. FELT HE PROBABLY WOULD HAVE FLOWN OVER ARPT COMPLETE CIRCLE RATHER THAN JUST DOWNWIND. REASON HE CALLED UNICOM WAS TO ALERT CUSTOMS AND THIS WAS PART OF WHY HE MISSED TWR FREQ.