HDG TRACK DEV WHILE IN ATA CAUSES GREAT CONCERN TO ATCT LCL CTLR.

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I DEPARTED BTR ON RWY 4 AND WAS CLRED FOR L TURN AND A HDG OF 330 DEGS. AFTER PICKING UP A 330 DEG HDG THE TWR ADVISED ME I WAS SUPPOSED TO FLY 330 DEGS THEN WANTED TO KNOW WHAT HDG I WAS FLYING. I REPLIED 320 DEGS AND MADE A CORRECTION FOR 330. THE CTLR THEN BECAME HOSTILE STATING I WAS NOT FOLLOWING DIRECTIONS AND WANTED TO KNOW IF I COULD HEAR HIM. I REPLIED YES. HE ASKED THE SAME QUESTION 2-3 TIMES AGAIN I REPLIED YES. AT THIS POINT I ASKED HIM IF HE COULD HEAR ME; HE REPLIED YES. AT THIS POINT I REALIZED HE HAD PROBABLY HEARD ALL YES REPLIES AND WAS JUST BEING AN ASS. ABOUT THE SAME TIME I FIGURED I MUST BE ON ABOUT A HDG OF 280-290 DEGS. I MADE A R TURN TO ABOUT WHAT I THOUGHT WAS 330 DEGS AND LEVELED OFF AT 2300 FT. I THEN WAS HANDED OFF TO DEP. AFTER CONTACTING DEP I WAS ASKED TO CLB BECAUSE OF AN ACFT HDG IN THE OPPOSITE DIRECTION AT 2100 FT AND 2.5 MI AWAY. AFTER THE LORAN SORTED ITSELF OUT IT'S HDG DIFFERED GREATLY FROM THE COMPASSES. UPON FURTHER INVESTIGATION I RECOVERED MY SCREWDRIVER (USED TO CHK OIL) ON TOP OF THE INST PANEL. THE SCREWDRIVER CAUSES THE COMPASS TO DEVIATE GREATLY DEPENDING ON WHERE IT IS PLACED ON THE INST PANEL. FROM NOW ON I WILL MAKE SURE THERE ARE NO FERROUS MATERIALS ON THE DASH AND WILL TRY TO FAMILIARIZE MYSELF WITH THE AREA SO I CAN RECOGNIZE A PROBLEM EASIER. I FELT THE CTLR WAS MORE CONCERNED WITH TRYING TO BE AN ASS THAN TRYING TO GET ME ON THE CORRECT HDG. HE COULD HAVE ASKED ME TO TURN R 40-50 DEGS AND NOT CROSS RWY 31 AND THAT WOULD HAVE CURED THE PROBLEM.