Receive problem in an IC-730

I have an Icon IC-730 transcever. I have a hunk of RG58U running out my bedroom window from the IC-730. There is about 75’ of wire connected to the center conductor and the wire is thrown over a tall tree and tied off to a fence post with nylon cord. The shield of the coax is floating. The radio acts like there is no antenna connected to it on receive. I plain on putting up a better antenna when funds are available. How do I fix this one to get the receive working?

Steve

If you can, put about 75’ of wire to the shield.