Soldering the wire togeather at the break will work fine and give no noticable difference in performance. As was stated, cover the joint with shrink wrap or liquid tape to protect it. If the break needs to go through an antenna tube then replacing the entire wire is the better way to go. The replacement wire is about $2-$3 and soldering to the circuit board is not hard if care is taken and the proper tools are used. I, for one, would never, ever send an rx off just to have the antenna wire replaced.