[time-nuts] Re: Coupling between oscillators -- an example

[ed breya]

Very interesting effects. I doubt that there was actually any 
injection-locking between the three Rb units, rather that you had all 
three frequencies presented together in various proportions, going into 
the test rig, due to the ground loops. For each signal being analyzed, 
there would be a tiny bit of the other two added by the ground.

I'm a firm believer in using signal isolation transformers where needed 
and practical. I've had plenty of issues with ground loop interference - 
usually from line frequency harmonics - especially between different 
pieces of equipment, but it can show up internally too.

You may get some more improvement by clipping a split-core ferrite 
common-mode choke onto each coax line. You could even put on a whole 
bunch of them, if you want. These should be effective at 5 or 10 MHz and 
well up into RF.

Ed