POTENTIAL CONFLICT BY 2 SMA'S AT A NON TWR ARPT. RPTR'S ACFT LOST XMITTING CAPABILITY AND THAT FACT WAS NOT DISCOVERED UNTIL AFTER DEP.

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AFTER START AND PRE TAXI CHKLIST COMPLETE; I HEARD AN ACFT CALL FOR ADVISORIES ON UNICOM. THE RESPONSE WAS 'WINDS FAVOR RWY 13.' THE PLT OF THE REQUESTING ACFT THEN REPLIED 'I'LL SET UP FOR RWY 13; I'M ABOUT 5 MI E.' I BEGAN TAXIING FOR RWY 36 AS IT WAS A SHORTER TAXI RTE. I FELT THE WINDS WERE CALM; AND I FELT CONFIDENT I COULD BE AIRBORNE PRIOR TO THE OTHER'S ARR. AFTER I COMPLETED MY RUN-UP; I ANNOUNCED THAT I WAS DEPARTING RWY 36. I HAD HEARD NOTHING FROM THE OTHER ACFT AND WAS CERTAIN I WAS DEPARTING WELL IN ADVANCE OF THE ARR ACFT. AS I WAS APCHING TKOF SPD; I SAW THE ARR ACFT ON VERY SHORT FINAL TO RWY 13. I USED SHORT FIELD TKOF PROCS TO CLR THE INTXN WITH AS MUCH ALT AS I COULD. LATER IN MY FLT; WHILE TRYING TO CONTACT GULFPORT APCH; I LEARNED THAT MY MIKE WAS NOT TRANSMITTING; ONLY THE SIDETONE IN MY HEADSET WAS NORMAL. I ASSUME MY DEP CALL WAS NEVER HEARD BY THE ARR ACFT; OR THAT PLT WOULD CERTAINLY HAVE QUESTIONED IT OR HAVE ADJUSTED HIS APCH TO RWY 13. 3 ITEMS ARE WORTH NOTING: 1) WHAT SOUNDS LIKE A NORMAL XMISSION IN ONE'S HEADSET MAY NOT BE A NORMAL XMISSION EXTERNALLY. MY MIKE WAS GOOD JUST 1 HR EARLIER. 2) TO TAXI TO A RWY DIFFERENT FROM WHAT IS RESPONDED TO AS THE FAVORED RWY BY UNICOM IS PROBABLY NOT THE BEST DECISION. 3) 'DOWNWIND;' 'BASE;' AND 'FINAL' CALLS WOULD HAVE PREVENTED MY DEP AT THE TIME I CHOSE; AND ALTHOUGH THE CONFLICT WAS NOT A SEVERE ONE; IT COULD HAVE BEEN HAD I BEEN 30 SECONDS OR SO LATER ON MY TKOF ROLL.