Mike, many thanks for your answer. Your right, first calibrate the BFO for display accuracy and then the DDS. There is a dependency between the BFO and DDS settings. Now I have the following on all 4 bands: display accuracy +- 100 Hz difference RX/TX frequency +- 50Hz 73 Uli DF5SF --- http://www.avast.com Outbound No Virus found.