Hi Rob,
Let me take a step back here for clarification. The tests you are performing are on the 868EM, but at 915MHz, correct? There was a previous post that described modifying the 868EM for 915MHz operation, so I'm wondering what these plots look like when run on the modified EM?
Also, if you look at the competitor board, zooming -in to look for 5MHz spurs, do you see them there as well? I'm wondering if they might be coming from another source, not the EM boards (either type).
-Leonard