USRP N200 with WBX 50MHz carrier signal quality

[chris@naluscientific.com]

Hi

I have a WBX sitting on an N200 SDR and want to use a carrier signal of 50MHz but when I'm testing it out and I hook it to my scope (50 ohm terminated) the signal looks like a comb - there are all kinds of higher order harmonics.  Is this expected?  The schematic for the system (WBX) has the LO created by a VCO and the datasheet for the VCO has its lowest output frequency at 137.5MHz but the card's sticker says it can do 50MHz on the low end so I wanted to figure out if it's something I'm doing wrong in programming it or what.  I tried submitting a support ticket but the site recognizes my serial number as an SDR to register it but won't let me create a support ticket because it doesn't recognize the SDR's SN (different systems I'm assuming?)

Any help would be appreciated.  Scope shot attached

 

Thanks

Chris