Problem solved. went back to basics, ran a ground buss connecting the rotor control case, radio case and computer case, and voila' no more USB disconnect. sheesh, thanks all Craig N6RSX Amsat no. 36607 NOTICE: This communication may contain privileged or other confidential information. If you are not the intended recipient of this communication, or an employee or agent responsible for delivering this communication to the intended recipient, please advise the sender by reply email and immediately delete the message and any attachments without copying or disclosing the contents. Thank you.