ADF41513 + HMC733 out of band spurs

Hi, 

I am using ADF41513 with HMC733 as my LO in my system. I noticed that there will be a fixed spurs at 5.7GHz to 6.2GHz with 100MHz spacing (my reference freq) regardless of my LO change from 10GHz to 20GHz.

See below photo:

1. Is the ADF41513 evaluation board having the same spurs?

2. If not, what is the possible causes of this spurs and how to solve it?

thank you.