The 72Mhz receivers are pretty sensitive to vibration. Make sure it is padded and protected well. I like to use 1/2 foam semi-losely wrapped and then using a velcro band to secure it to the airframe. Some folks like using rubber bands. The second issue I see and tend to agree with in this string here is prop balance. Get your prop balanced. Third thing is antenna routing. Keep it away from the battery leads and any metal to metal contact. Even a Z-bend rod with the servo connection to the throttle arm can cause some feedback into the radio with vibration. Finally try swapping out the reciever and see if that makes a difference. May have to borrow your field buddies radio for testing to make sure it is not a receiver issue....

Wish you the best with sorting it out.

Please share with all when you figure it out. We all learn from each other and become better fliers and friends.