Hi,
In order to compare GPSDO with Cesium as a reference the two 10 MHz signals is driven a SBL1 (Lo from Cesium & RF from GPSDO) and output (reminder IF is down to DC out) is feed to a scope at DC input. The 'fat' line is due to the 10 MHz leakage from both inputs and 20 MHz mixing signal. No noticable 'oscillation' of the wave is noticed.