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.

Reply via email to