Hi If you are measuring the OCXO, you should be getting around -155 to -160 dbc / Hz at 100 Hz offset. Depending on the particular board you have, and how it is powered, the numbers out of the TBolt can be quite a bit worse than this. With a good supply, you should get within 5 db. There are a lot of spurs, so you do need a pretty good (narrow bandwidth) analyzer to sort them out from the noise floor.
Bob > On Sep 18, 2016, at 8:42 AM, David C. Partridge > <david.partri...@perdrix.co.uk> wrote: > > I've just redone the measurement without the external attenuator and with > 10dB attenuation set internally to the analyser. > > The results are attached. > > Dave > > -----Original Message----- > From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bruce > Griffiths > Sent: 18 September 2016 12:52 > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Thunderbolt spurs on 10MHz output at 100Hz and 200Hz > from signal. > > The signal level is also very low. > Brue > > On Sunday, 18 September 2016 11:47 PM, Magnus Danielson > <mag...@rubidium.dyndns.org> wrote: > > > The phase-noise still looks fairly high. How do you measure this? > > Cheers, > Magnus > > On 09/18/2016 01:27 PM, David C. Partridge wrote: >> Now that's interesting I just re-ran the measurement, and got a quite >> different result which is attached. The spurs have GONE. >> >> My only guess right now is that the E4406A power supply is getting quieter >> as it has been on for longer (I've only had it powered for short periods >> before now). >> >> Dave >> >> -----Original Message----- >> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of >> Magnus Danielson >> Sent: 18 September 2016 11:56 >> To: time-nuts@febo.com >> Cc: mag...@rubidium.se >> Subject: Re: [time-nuts] Thunderbolt spurs on 10MHz output at 100Hz and >> 200Hz from signal. >> >> Hi, >> >> On 09/18/2016 12:26 PM, David C. Partridge wrote: >>> The local power is 50Hz, so I can understand the 100Hz spurs, but I >>> don't quite "get" where the 200Hz spurs are coming from. Or is that >>> just BAU harmonics? >> >> Consider full-wave rectification of 50 Hz, the power consumption load >> on the capacitor after the rectifier creates an inverse sawtooth wave >> of >> 100 Hz, and sawtooth waveshape have both even and odd harmonics. >> >> While much of this is regulated out in the next step, some of it makes it >> though. >> >> Cheers, >> Magnus >> >>> >>> >>> Thanks >>> >>> Dave >>> >>> >>> >>> _______________________________________________ >>> 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. >>> >> _______________________________________________ >> 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. >> >> >> >> _______________________________________________ >> 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. >> > _______________________________________________ > 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. > > > > _______________________________________________ > 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. > <Thunderbolt pn3.png>_______________________________________________ > 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. _______________________________________________ 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.