Go to www.harbachelectronics.com
and purchase a soft key module for the SB-200. Price two years ago was $22 including shipping. Easy to install yourself, directions are clear, and you'll never have to worry about harming the keying relay on your TS-850. Harbach is now run by Jeff W8CQ, nice fellow to do business with. He also has a number of other mods for the SB-200, some of which I have installed in mine. By the way, I just checked Jeff's web site. He has posted a message saying he's moving to Ohio and the product descriptions and ordering instructions will not be available on the web site until December 1.