INSTRUCTOR WITH SPI IN A C172 PRACTICING TOUCH-AND-GO LNDGS HAS A CONFLICT WITH A CPR JETSTAR MAKING A STRAIGHT IN APCH TO AN UNCTLED ARPT.

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I WAS DOING TOUCH-AND-GOES WITH A STUDENT AT COLES COUNTY ARPT. WE HAD BEEN IN THE PATTERN FOR APPROX 20 MINS. WE HAD BEEN ANNOUNCING ON CTAF THE ENTIRE TIME. DURING A CLBOUT FOLLOWING A TOUCH-AND-GO; I OBSERVED A JETSTAR APPROX 1 MI NE (MY 4-5 O'CLOCK POS) IN A CLB. I HAD NOT SEEN OR HEARD ANYONE UP TO THIS POINT. WE EXTENDED OUR UPWIND A LITTLE TO ALLOW THE JETSTAR TO TURN XWIND FIRST. I SWITCHED TO A SECOND COM RADIO. WE CONTINUED TO ADVISE OF OUR POS AND EVENTUALLY HEARD THE JETSTAR CALL FINAL. WE DID 2 MORE TOUCH-AND-GOES AFTER THE JETSTAR HAD LANDED. ONCE DOWN AND CLR OF THE RWY; THE CREW OF THE JETSTAR ACCUSED US OF 'ALMOST CAUSING AN ACCIDENT.' I DID NOT ENGAGE IN CONVERSATION OVER CTAF WITH THEM AS I WAS STILL IN THE AIR. I BELIEVE THERE WERE 2 FACTORS WHICH CONTRIBUTED TO THIS EVENT. THE BIGGEST FACTOR WAS THE JETSTAR'S CHOICE TO DO A STRAIGHT-IN FINAL AS ENTRY TO THE PATTERN. I DON'T KNOW FOR SURE HOW FAR OUT THE JETSTAR WAS WHEN WE TURNED BASE TO FINAL; BUT I WOULD ESTIMATE AT LEAST 5 MI. MY STUDENT AND I WERE SCANNING FOR TFC AND NEVER SAW THE JET. WE WERE FLYING AT ABOUT 65-70 KTS ON FINAL. OBVIOUSLY; THE JET WITH 4 ENGS WOULD HAVE BEEN GAINING ON US. DUE TO THE FACT THAT HE WAS STILL BEHIND US AND TO THE R SLIGHTLY AFTER WE HAD DONE OUR TOUCH-AND-GO; HE HAD TO HAVE BEEN AT LEAST 5 MI OUT WHEN WE TURNED FINAL. VISIBILITY WAS ABOUT 5-6 MI WITH HAZE. THE STRAIGHT-IN WAS BAD JUDGEMENT. ANOTHER CONTRIBUTING FACTOR WAS THAT OUR RADIO WAS INOP. AFTER SWITCHING RADIOS; WE WERE HEARD. HOWEVER; DURING THE PORTION OF THE FLT DISCUSSED BEFORE THE SWITCH; WE WERE NOT HEARD AND WE RECEIVED NOTHING AS WELL. THE TREND OF LARGER ACFT TO ENTER A NON CTLED ARPT PATTERN STRAIGHT-IN ON FINAL IS A DISTURBING ONE. THE ACFT IS MOVING QUICKLY WHICH ALLOWS LITTLE TIME FOR IT TO BE SEEN. IT ALSO ALLOWS VERY LITTLE TIME FOR THE CREW TO OBSERVE OTHER TFC. NORMALLY; THESE STRAIGHT-IN FINALS ARE DONE IMMEDIATELY AFTER THE CREWS SWITCH TO CTAF. THIS MEANS THEY HAVE ALSO HAD NO TIME TO LISTEN TO TFC. THIS COULD EASILY LEAD TO MORE PROBS LIKE QUINCY; IL; IN VFR CONDITIONS.