CHARTER ACFT HAS ADF FAILURE.

Narrative

I WAS GIVEN A CLRNC BY ZTL TO DSND TO 4000 FT AND PROCEED DIRECT TO THE EMANUEL COUNTY ADF RADIO BEACON. I HAD THE BEACON TUNED IN AND VERY FAINTLY IDENTED. I SAW THE BEARING POINTER ABOUT 60 DEGS OFF THE NOSE TO THE L SO I MOVED THE AUTOPLT HDG BUG 60 DEGS AND CONTINUED TO STUDY THE APCH CHART. AFTER THE TURN THE ADF POINTER WAS ABOUT 45 DEGS STILL OFF TO THE L SO I FOLLOWED IT. I NOW REALIZED THE BEARING POINTER WAS NOT FUNCTIONING PROPERLY SO I CONTINUED THE TURN TO THE L -- ALMOST 360 DEGS AND THE CTLR CALLED AND WANTED TO KNOW WHY I MADE A 360 DEG TURN. I TOLD HIM I COULDN'T GET A GOOD 'LOCK' ON THE BEACON. HE SAID BY NOT GOING DIRECT TO THE BEACON I CAME WITHIN 4 MI OF AN AIRPLANE CLBING THROUGH MY ALT AND THIS CREATED A 'DEV.' AFTER LNDG I CALLED MY COMPANY AND RPTED THE ADF AS BEING UNRELIABLE. I WAS ASSIGNED AN MEL NUMBER. I LEFT SBO AND PROCEEDED TO SAV WHEREAS I CALLED THE COMPANY AGAIN. THEY INFORMED ME ZTL HAD CALLED AND RPTED THE DEV. I DID NOT KNOW THE ADF WOULD NOT 'POINT' AS I RECEIVED AN IDENT SIGNAL AND THERE WAS NO HISTORY OF IT BEING UNRELIABLE. BY THE INDICATIONS I RECEIVED I THOUGHT I WAS GOING DIRECT TO THE BEACON.