PLT OF SMA INADVERTENTLY IN ATA TURNED OFF TRANSPONDER.

Narrative

I HAD DEPARTED LANSING; IL UNCTLED ARPT (3HA) TO GO TO FRANKFORT; MI (3D4) TO TAKE 2 FRIENDS UP THERE TO RETURN THEIR SAILING BOAT FROM A SAILING RACE. THE WIND WAS BLOWING FROM THE SSW AT 10-15 KTS. MY CRUISING ALT WAS TO BE AROUND 3000-3500 FT MSL. AFTER DEPARTING 3HA I WAS CLBING TO CRUISE ALT WHEN MY FRIEND SAID 'LOOK; WE ARE OVER GARY ARPT'. I THEN LOOKED AT MY ALTIMETER WHICH INDICATED ABOUT 2500-2600 FT MSL. IT WAS HOT THAT DAY ABOUT 90 DEG. I FELT THAT I WAS CLBING GOOD ENOUGH TO MISS GARY; IN (GYY) ATA BY A WIDE MARGIN BUT I GUESS I MISCALCULATED. THERE WAS NO TFC OBSERVED IN THEIR ATA. MY TRANSPONDER/ENCODER WAS ON AND OPERATING NORMALLY. AFTER FEELING STUPID ABOUT THE ERROR; I TURNED MY TRANSPONDER/ENCODER OFF FOR THE NEXT 30 MINS. I KNOW CHICAGO CENTER WOULD BE ABLE TO TRACK MY TRANSPONDER BUT WOULD LOSE MY TARGET OUT OVER THE LAKE BECAUSE OF POOR COVERAGE. I WAS WELL AWAY FROM THE TCA SO THAT DID NOT PRESENT ANY PROBLEMS. SOUTH BEND RADAR DOES NOT HAVE COVERAGE OVER THAT FAR W AT LOWER ALTS. SO AFTER PASSING N OF BENTON HARBOR I RECYCLED MY TRANSPONDER ON AND CONTINUED MY TRIP. I HOPE THIS WASN'T A BIG CONCERN FOR GYY ATA. I WILL BE MORE ATTENTIVE TO MY CLBS AND AREAS FROM NOW ON. I DID LEARN A LESSON FROM THIS. THANKS FOR BEING A FRIENDLY LISTENER.