I bought my cable from this guy. I read thru all his positive feedbacks, and it works beautifully. Had to do nothing to get it up & running. I emailed RT AND BuTel. Both said they have no cable or software that will work with this radio.
Bluemax49ers.com. Good prices, he has the software link if you need it. spend some time in the site. Hopefully you will be as pleased as me. The software is a whole different story. very time consuming, buy once you mess with it for awhile, it isn't so bad. Just very, very outdated.
Good Luck.