Hi Mike,
I recently bought an RT-11 from an estate auction. It came with the Icom wiring. I'm using it with a Kenwood TS-2000 so I built a smaller version of the remote head and that setup has been working fine for me.
I'd be happy to make a? deal with you on this cable if you're interested, or I can provide you an actual pin-out if you want to confirm your cable.
Have you tried the setup with a dummy load? At least you can remove one variable with that.
Doug
WA7DJS
Lynden, WA.?
Doug WA7DJS