I put a spreadsheet to help calculate the true DDS oscillator frequency in the Files section. It allows a normal operating frequency to be used instead of an out of band frequency.
Make sure that you have an adequately warmed up oscillator and receiver since you are likely measuring the offset in single or tens of Hertz only. Then your on the air transmissions can be confirmed with receiving stations of good quality. In my case there are several WSPR stations on 80 meters that have rubidium or GPS disciplined receivers. When they all agree on my frequency, I have confidence in it.
Paul KE7HR in Phoenix, AZ
