The PC cable description is in appendix B of the synscan manual.
I did find these people on the web (uk) that sell made up cables
http://www.axio35.dsl.pipex.com/astr...a%20cables.htm
I have not used these people before so can't vouch for them.
BTW GSL, what version of the Synscan are you using?
The reason I ask is that the same cable can be used to upload new firmware into the Synscan in V3.