Yesterday afternoon we made some additional test to confirm that this additional noise was coming from the new LNFS. 

We used one of the two free output of the LNFS used now for the 22MHz  to generate a twin 56MHz signal to feed *only* the demodulation box (not the EOM). In fig. 1 we can observe that the noise disappears in the LNFS dfreq channel, but not in the EOM one, confirming that there is an issue with this device.

For the time being, the only one possibility left for the generation of the 6/8/56MHz  is to use the LNFS used up to Monday morning, which appeared to be more noisy than usual , but good enough to work on the interferometer.

We replaced the old LNFS at 14.45UTC.