I was thinking to tap-off the Ocxo itself with a small buffer and bypass all of the internal stuff. Will report on that later..
Sent from my iPad On Nov 27, 2010, at 9:22, "W2HX" <[email protected]> wrote: > 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. _______________________________________________ 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.
