ExpertGPS Pro can export DXF to AutoCAD and other CAD packages, and you can use ExpertGPS to convert your DXF to KML and other formats, and to send CAD points and polylines to your GPS as waypoints and tracklogs.
To export your DXF, first confirm that the coordinate format and datum you are using in ExpertGPS match the X,Y coordinate system you are using in your CAD software. If needed, click Change Coordinate Format on the Options menu. Then, click on the to create the DXF file.
If you DXF data from ExpertGPS doesn't line up properly with the other data in your CAD software, double-check that the coordinate format and datum in ExpertGPS match the coordinate system you are using in AutoCAD. For example, if you are working with meters in AutoCAD, but are using latitude and longitude in ExpertGPS, the X, Y values in the DXF will be degrees of longitude and latitude instead of meters. Switch to UTM, state plane, or another format that uses meters.
If the scale appears to be off by about a factor of 3, the problem may be that one system is using meters, and the other system is using US Survey Feet. Again, double-check the coordinate format and datum settings in ExpertGPS and your CAD software.