TFC WATCH ACFT TAXIED AND TOOK OFF FROM PDK WITHOUT CONTACTING THE TWR.

Narrative

THE FOLLOWING CHAIN OF EVENTS LED TO MY DEP FROM DEKALB- PEACHTREE ARPT (PDK) WITHOUT CLRNC TO TAXI OR TKOF. UPON ENG START AT ABOUT XA45 AM; I TUNED THE PDK ATIS; AND RECEIVING NO BROADCAST; MY BELIEF THAT THE TWR OPENED AT XB00 AM WAS CONFIRMED. I PROCEEDED TO MAKE TFC RPTS ON THE CTAF AND DEPART THE ARPT FROM RWY 2R. AFTER CLRING THE ATA SWITCHED TO THE FREQ USED BY TFC RPTRS IN THE METRO ATLANTA AREA TO MAKE POS RPTS. AT THIS TIME I REALIZED MY RADIOS HAD BEEN IMPROPERLY SET AND I CALLED PDK TWR FOR A RADIO CHK. THEY INFORMED ME THAT THE TWR HAD BEEN OPEN SINCE XA30 AM AND THEY HAD WATCHED ME DEPART WITH NO CLRNC. FACTORS WHICH I BELIEVE LED TO THE DEV ARE: 1) PLT FATIGUE -- AS A BACKUP TO THE NORMAL TFC PLT; I WAS NOT ADJUSTED TO THE EARLY HRS. 2) UNFAMILIARITY WITH THE ACFT -- THIS WAS ONLY MY SECOND FLT AS PIC OF THE SPECIFIC ACFT. HAD I BEEN MORE FAMILIAR WITH THE RADIOS IN THE ACFT I WOULD HAVE ADJUSTED THEM PROPERLY AND RECEIVED AN ATIS WHICH WOULD HAVE ALERTED ME THAT THE TWR WAS ALREADY OPEN. 3) PRESSURE TO PERFORM WELL ON MY FIRST TFC FLT WITHOUT THE REGULAR PLT ALONG MAY HAVE LED TO HASTY PREPARATION. HAD I TAKEN MORE TIME DURING THE TAXI AND RUN-UP; I MAY HAVE DETECTED THE RADIO ERROR BEFORE DEP.