First off, I would check your cabling, make sure that it’s all good and secure. Also make sure it’s sealed properly so that water cannot get into it.
From there, I would swap Chain 1 and Chain 2’s cabling to the antenna, it doesn’t really matter which way they are connected anyways, and see if the problem is on the radio/cable/antenna side. Keep swapping around the cables until you isolate the issue. Or you could swap out the radio, but that will probably take up a lot more time.