I wonder if the 19.6608 isn't needed, if one could unsolder the logic divider chips and reduce noise?
73 Eugene W2HX -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Bruce Griffiths Sent: Saturday, November 27, 2010 12:44 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] ok, newbie questions Those switch mode regulator modules under the finned heatsinks in the Z3815A are likely responsible for most of the spurs. The ECL/CML logic dividers and the various ouputs like 19.6608MHz also contribute. Since the E1938A output is only +4dBm, its very easy to degrade the phase noise in the buffer chain if one isnt careful. With careful design a discrete buffer amp phase noise floor below -170dBc/Hz should be possible with a + 4dBm input. Bruce [email protected] wrote: > Not necessarily so.. > > My HP Z3815A here (desktop unit) has horrible phase noise and massive > spurs. Really to cry over since I know what the internal OCXO (1938A type) is > capable of generating. > > See the attached plot. > > bye, > Said > > > In a message dated 11/26/2010 16:37:26 Pacific Standard Time, > [email protected] writes: > > So if I want a really souped-up freq standard for my lab, then I should > concentrate on finding the best oxco I can (which may be disciplined by > the > GPS or manually occasionally calibrated to GPS), and use the best power > supply I can find. These seem to be what I should concentrate on rather > than more channels. > > I do believe that I read some stuff on the internet that the HP GPS DO's > do > seem to have very good power supplies (or converters) which contribute to > low spurs. So it seems the HP's do have a real advantage (not just the > name). > > > > > > _______________________________________________ > 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. _______________________________________________ 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.
