DEPARTING A NON TOWERED ARPT; C180 PLT BARELY AVOIDS TKOF INCIDENT WHEN HE TRANSMITS ADVISORIES ON THE WRONG FREQUENCY WHILE MONITORING THE CORRECT FREQUENCY.

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I WAS DEPARTING DRO AT APPROX XA10 AM AND THOUGHT I WAS ANNOUNCING ON 122.8 (UNICOM) FROM RADIO #1. IT TURNS OUT THAT I WAS LISTENING ON 122.8 BUT BROADCASTING ON ANOTHER FREQ ON RADIO #2. ABOUT 30 SECONDS AFTER MY BROADCAST (ON WRONG FREQ) FOR 'TAXI' AND A FEW MINS LATER FOR 'INTXN TKOF ON RWY 2;' A SCHEDULED CARRIER ANNOUNCED ON 122.8 INTENTIONS TO TAKE OFF ON RWY 20. I HEARD THIS ANNOUNCEMENT AND ALSO SAW THE DEPARTING ACFT STILL IN THE RUN-UP AREA AT WHICH POINT I STOPPED ON THE TXWY AND HELD SHORT OF MY INTXN TKOF POS TO CLR UP CONFUSION. DRO ARPT OPS WHO WAS MONITORING THE FREQ HAD SEEN ME GETTING READY TO DEPART AND ANNOUNCED ON 122.8 TO THE ACR THAT I WAS DEPARTING. THE ACR THEN ANNOUNCED THAT IT WOULD HOLD SHORT FOR ME. HEARING THAT ON 122.8; I ANNOUNCED MY TKOF (AGAIN ON WRONG FREQ) AND I DEPARTED. SHORTLY AFTER TKOF I REALIZED I WAS ONLY LISTENING ON 122.8 AND NOT XMITTING ON IT; AND CORRECTED THIS BY SWITCHING TO XMIT ON RADIO #1. I THEN SPOKE WITH ARPT OPS AND CLRED UP MY MISTAKE. TFC WAS NOT JEOPARDIZED IN THIS PARTICULAR INSTANCE DUE TO MY LISTENING ON 122.8 AND THE GOOD VISIBILITY. HOWEVER; I WAS REMINDED OF HOW IMPORTANT IT IS TO XMIT ON THE PROPER FREQ. PARTICULARLY IN UNCTLED AIRSPACE IT IS NECESSARY TO CONFIRM THE RIGHT FREQ BECAUSE ONE DOES NOT AUTOMATICALLY HAVE THE 2-WAY COM FEEDBACK. DRO ARPT OPS IS ALSO TO BE COMMENDED AS THE OPERATOR MONITORING UNICOM WAS VERY OBSERVANT AND HELPFUL EVEN THOUGH ARPT OPS DID NOT HAVE GND OR ATC RESPONSIBILITY. THE OTHER LESSON IS THAT COMPLACENCY CAN SNEAK UP ON EXPERIENCE AND; AS FOR ALL PLTS; MUST BE FOUGHT OFF -- EVEN FOR ME.