> Bottom line, the large low-frequency spurs in the FTS plot at 1.4 and 2.9 > Hz > will be caused by one of these conditions: > > 1) A problem with the reference source(s) > > 2) A problem with the FTS oscillator itself > > 3) A normal characteristic of the FTS oscillator (maybe its spur specs > weren't very good to begin with?)
It seems the FTS1200 is only slightly out of spec compared to http://www.ece.gatech.edu/academic/courses/ece4007/08fall/ece4007l01/al4/datasheets/symmetricon_oscillator_instructionsheet.pdf http://rubidium.dyndns.org/~magnus/time/timelab/FTS1200_OSA8600_OSA8601_20120802_1.png > > 4) An RF crosstalk or leakage problem with the cables/adapters used > > 5) A power-supply regulation issue > > 6) Coupling between inadequately-bypassed power leads. This is a big > problem with some OCXOs where they apparently forgot to use bypass > capacitors inside the can. I usually solder a 0.1 uF ceramic chip cap > right > at the point of entry, if in doubt. > > 7) Some as-yet-unexplored effect related to beatnotes in dual-reference > measurements. > > It may be possible to rule out cases (2) and (3), and definitely case (7), > by temporarily switching back to the normal single-reference > configuration. > > -- john, KE5FX > www.miles.io > -- Björn _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
