Hi Do you have any idea how “clean” your 200 MHz signal is? The manual suggests getting it to -65 dbc for subs using a spectrum analyzer. That’s pretty far down. I seem to recall the adjustment process being a bit tedious (lots of back and forth).
Bob On Mar 2, 2014, at 5:29 PM, Poul-Henning Kamp <[email protected]> wrote: > > I have spent another evening playing around with the 5370 and the > conclusion is pretty ironclad now: > > Running a 5370 with ext-ref locked to input frequencies is simply > a bad idea and should not be done. > > Running it on the internal OCXO works fine. > > Running it on another frequency *not* locked to the input frequenc > also works fine. > > In both cases the errors are statistically well-behaved, and can > be treated with normal statistical methods, including the built-in > STD-DEV function. > > But feeding ext-ref a frequency which is locked to the input frequencies > causes the errors to become systematic, and they can no longer be > treated as statistically well-behaved. > > For instance: The length of the coax to ext-ref suddenly affect > your TI measurements, because it shifts the phase between the 200MHz > and the input signal. > > I tried tuning up the A21 200MHz synthesizer to the best of my > ability, and it clearly made a difference, the phase pattern > of errors shifted around, but the errors did not get any smaller, > they just moved. > > I also tried disconnecting the "10 MHz present" circuit, that > didn't change the magnitude of the errors either, but did shift > the phase of the peak noise a couple of degrees. > > Looking at some old notes from years past which just didn't make > sense, does now. > > -- > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > [email protected] | TCP/IP since RFC 956 > FreeBSD committer | BSD since 4.3-tahoe > Never attribute to malice what can adequately be explained by incompetence. > _______________________________________________ > 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. _______________________________________________ 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.
