AD9959 evaluation board output at higher frequencies

I am trying to drive the ad9958/ad9959 with the software and an external reference clock. For the application I have in mind I would need a good output at higher frequencies. I tried to output 100 MHz, but the output seems really bad. Is there something I am missing that is necessary for higher frequencies output? 

Best Regards!



Added picture
[edited by: SSchott475 at 1:03 PM (GMT -4) on 5 Oct 2020]