I extended my wire about 15 ft on my unit. It was a simple job for me to do and the unit works fine.
I have been working in the television industry for a major TV network for 24 years with our Engineering / Integration dept so doing this was a no brainier for me.
The cable I used to extend the wire was Belden 83264 it is just about the same size as the original but the only drawback was the color...its brown vs black. I just made sure the extension was hidden.
I don't remember if the center conductor was braided or not, not a big deal if it is just tin the wire if it is
Basically all you do is do a western union splice on the center conductor....insulate with heat shrink then wrap the two shields around each other and solder them, then insulate with heat shrink you also want to make sure it water tight if its outside
If you want I can post pics on how it done