Extracting from .cop.sgn files

Hi,

I want to manually upgrade the firmware on a couple of 7940's. I have the firmware I wish to use in a .cop.sgn file and I have read that I would need to extract the phone load from this file before I can use it in the manual upgrade. I have tried renaming it as .tar.gz .tar .7z .rar .zip and used 7zip and winrar but I cannot extract any files. Any ideas?

Cheers
Waru