I have a Kenwood TS-850AT that I have owned since new in 1991.
I bought a Kenwood DSP-100 about 6 years ago and returned it to the seller because it would not work. The seller (who was very nice) sent me a video after he received it, and it was working just fine.
I bought another DSP-100 about 5 years ago and it has the same problem. I'm beginning to wonder if my TS-850AT is the problem. It sure appears to be.
Is there anyone within a 250 mile radius of Memphis, TN that could help me test this on another TS-850AT? I'll drive to your QTH...
KN4YH