SMA X ENTERED CLASS D AIRSPACE WITHOUT CLRNC AFTER XMITTER FAILED.

Narrative

DEPARTED RYY ENRTE TO FTY. WHEN I CALLED FOR RADIO CHK; I RECEIVED 'LOUD AND CLR.' RADIO WAS RECEIVING FINE. WHEN I CALLED COUNTY TWR FROM OVER THE TAUK FARM (10 MI); I AGAIN HEARD WHAT I THOUGHT WAS A RESPONSE (IN RETROSPECT; I BELIEVE THE TWR WAS TALKING TO ANOTHER ACFT). WHEN I NEARED THE FIELD; HAVING DSNDED TO 2000 FT AND HAD STILL RECEIVED NO FURTHER INSTRUCTIONS; I AGAIN TRIED TO CALL THE TWR; BUT RECEIVED NO RESPONSE. ALL THE TIME I COULD HEAR THE TWR TALKING TO OTHER ACFT. LEAVING 2000 FT FOR 2500 FT I BEGAN TO CIRCLE W OF THE FIELD WHILE TRYING TO CONTACT THE TWR. I PLUGGED AND UNPLUGGED THE MIKE; TRYING DIFFERENT JACKS UNDER PANEL -- STILL NO CONTACT. FINALLY; I DECIDED TO RETURN TO RYY AND CROSSED FTY MIDFIELD AT 2500 FT. I COULD HEAR THE CTLR WARNING OTHER PLTS OF MY PRESENCE AS I DEPARTED TO THE N. BACK AT RYY I ATTEMPTED TO CONTACT LCL TFC TO NO AVAIL. AFTER LISTENING TO DETERMINE THE LEVEL OF ACTIVITY IN THE PATTERN; I ENTERED THE BASE LEG FOR RWY 9 AND LANDED WITHOUT INCIDENT. IN THE FUTURE; I WILL BE MUCH MORE CAREFUL AS A STUDENT TO MAKE SURE THE TWR IS TALKING DIRECTLY TO ME.