NMAC AT NON TWR ARPT WHILE IN THE TFC PATTERN.

Narrative

WHILE APCHING ASW (WARSAW; IN) FROM THE ENE; I USED MY RADIO TO CANCEL MY FLT PLAN WHEN THE ARPT WAS IN SIGHT. THEN WHEN I TRIED TO CONTACT ASW UNICOM; THE RADIO SEEMED FULL OF INTERFERENCE. IT LATER TURNED OUT THAT I HAD ACCIDENTALLY LEFT THE VOLUME KNOB ON THE COLLINS RADIO PULLED OUT (SO AS TO DEFEAT THE SQUELCH). THIS MADE CONTACT DIFFICULT. I MAY HAVE HEARD SOMEONE SELF-ANNOUNCE DEP ON RWY 18 FROM ASW; BUT I AM NOT SURE. I ANNOUNCED ON THE CTAF WHEN I WAS 2 MI E OF THE FIELD THAT I WOULD BE ENTERING A DOWNWIND FOR RWY 18; L-HAND TFC. I HAD JUST REACHED ABOUT 1700 FT MSL AND ESTABLISHED A HDG OF 360 DEGS WHEN I SUDDENLY BECAME AWARE OF A GRAY HIGH WING ACFT AT A LOWER ALT CLBING TOWARD ME ON MY L. HE LOOKED LIKE HE WAS ON A HDG OF 090 DEGS AND HE PASSED JUST BEHIND ME ABOUT 250 FT AWAY. I WAS SOMEWHAT UPSET; BUT THE LNDG CONTINUED NORMALLY. THE NEAR MISS APPEARED TO HAPPEN JUST ABOUT IN LINE WITH RWY 9 AT WARSAW. I BELIEVE I WOULD HAVE BEEN MORE AWARE OF TFC IF MY RADIO WAS NOT MISADJUSTED WITH THE VOLUME KNOB PULLED OUT. I HAD ALSO NEGLECTED TO TURN ON MY LNDG LIGHT ON APCH TO ASW.