There is a resistor that you can change. I don't remember which one, but it is around 3M, that you change to 1M. Should work well up to around 30-35WPM at that point. At least that is what I remember. It's been a long time. NRE/COLE Test Center OH-3 [email protected] or [email protected] Philip L. Carter, WD8QWR K2 #370 wd8qwr@w8cqk.#cmh.oh.usa.na