I was flying my Chipmunk for the 2nd flight and all of a sudden the plane was jumping and the throttle erratic. I got hit 3 more times before landing, which I did immediately. I checked out everything on the ground and found nothing amiss. I checked the freq board and saw that someone was flying on ch 14 ( I'm on 13). I waited until the person was done flying and had them come over to check for interference. I turned on my rcvr(127fm) and got no glitching. I Had the pilot turn his xmttr on and got no glitching until he extended his antenna half way at which time my controls went nuts. I am using a 9C with 127fm rcvr on low band ch13. His xmttr is a T6x on ch14. We performed this check 2 times with the same result. My radio is barely a year old as is his. My rcvr is new. I had no previous problems with adjacent channels interfering with my planes and ground checks have always been fine. I suspect that his xmttr is bleeding over to my ch or his xtal might be drifting slightly. I would appreciate any positive feedback on this as well as recommendations. On a different note, I have also experienced the Rudder glitch with all my planes with the 9C and several different rcvr's. It would seem to me that there might be an issue with the 9C xmttr IMO. Thanks in advance.

It's entirely possible the other transmitter is off channel. It could also be possible that your receiver's off. One way to check would be to use a different transmitter that's also one channel off your frequency. If the receiver still glitches, it's likely the receiver. If it doesn't, then it could be that one other transmitter.