I have an old IC-735 at the remote QTH. The IC-735 use a "dialect" of CI-V that differs from the later implementations Icom did. This is well known and well documented. (If interested, I can explain the difference. But it might be easier to look at any versions of HRD. They support the IC-735 and you can see the difference in the protocoll there) I do understand if you don't plan to spend time on this old radio but wanted to mention it. 73's de SM0NZY