I sent my RC in for repair, the RTH button had fallen into the controller as have others. No problems with the RMA, received new RC in 14 days. I sent in the 300A and received a 300C in return. Nothing else has changed. Same firmware, same settings absolutely nothing else has changed. I fly from my front porch all the time. I am in the country. I am sitting above everything else around. Used to go to at least 9000' before any type of signal loss. It was a given, never varied more than 1000'. Now when I get to about 1000 I start to get blackouts on the screen. Got to about 5000' and started to lose RC signal. I am thinking the 300C could be the problem? Your Thoughts?