> > Yours is actually better than spec... my Efratom FRS-C manual says the > > spec is -70 at 1 Hz offset, -110 at 100 Hz, -130 at 1 kHz. The notation > > is a bit odd though -- it says "dBc/sqrt(Hz)". > > You're looking at the Thunderbolt trace, I'm guessing... I'm only > getting -117 dBc/Hz at 1 kHz out of the Datum, -142 dBc/Hz at 1 kHz out of > the Thunderbolt.
Just measured the FRS-C by itself, and it does appear to meet that specification ( http://www.thegleam.com/ke5fx/compare.gif, 30KB). So Datum is just running it through a noisy signal chain on the way to the back panel. > > My understanding is that the compact telecom Rbs put FM on the reference > > as part of the lock mechanism; that makes the phase noise fairly ugly. I can see that happening with a scope during the first minute or two of warmup time, but it goes away after that. -- john, KE5FX _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
