Just a thought. When you order the SignaLink USB, they have pre-wired modules for various radios that make the internal jumper setting of the SignaLink fool proof.
The wiring itself is not hard, but I can actually change my SignaLinks to work with my different radios in less than 30 seconds and am assured that the wiring inside is correct. Pretty good bargain for $8 or so when you order.
Every time something is made fool proof, somebody comes up with a better fool :-)
Thanks for the info. I hadn't paid any attention to the wiring modules. I'll look into them.