Hi Paul. SD_CALWIN is about 8000 or 9000. If I edit it down to about 2000 with notepad, save the settings then restart SD the CW is still extremely poor with sidetone OFF but OK with sidetone ON. It is slow and the dots and dashes seem truncated - difficult to read. When I go back to SD.INI again, then SD_CALWIN has gone back up to 8000/9000 again. Danny, G3XVR