Here is what I had to do with my Magellan
It came with cable that was smaller than anything Radio Shack sells including the plug. (I'm talking about the Antenna.) Of course, it was 18" too short for the radar arch. To make a long story short, after finding a supplier on the web, I still had to cut the coax to snake it to my nav station. The cut was made and after pulling the wire into the clear, I stripped the center conductor back enough to solder, but first, I positioned shrink tubing. I made the connection, moved the tube in place and shrinked it. (that's not a word) Then the outer strands had to be connected. All I did was twist them into a wire like lead and solder them together. I then wrapped aluminum foil around that part of the joint to act as shielding. (just in case) More shrink tubing finished the joint. It works perfectly