Addendum to last post: I've already ordered and received another emulator, and physically replaced the instrumentation amplifier. Results exactly the same. RF Solutions tech support for the emulator is in the UK, so i doubt i'll get any help from them until next week. Phil Eisermann Electronics Engineer The Ridge Tool Company (440)329-4680 -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics