I believe I've discovered a subtle bug in the RF Gain calibration code that could possibly cause the problem you're describing. Please try this version and let me know if it solves the problem. http://sight.net/K3/K3Util/10-27-2009/K3UtilityOSX.zip (7.5MB) tnx, David, W4SMT > I agree. Something is not right > here.