There is a 10x improvement in the Marconi phase noise spectrum when locking it to the FS725 Rubidium clock.
To see if we could improve on the Marconi spectra for use in the Gyro/RefCav measurements I set up two of the 40m Marconis for "Direct External 10 MHz Reference" lock.
In the attached plot you see the BLUE trace (free running Marconis) is higher than the PURPLE (locked to Rubidium) trace. The BROWN dots are the SSB phase noise specs
for the FS725 Rubidium clock. In this case, I have the FS725 locked to the 1PPS from our GPS receiver, but I think it doesn't have any effect above 10 mHz.