Still way above what it should be.Whats the noise floor of the measurement
system?
Bruce
On Monday, 19 September 2016 12:43 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
>>
>>
>>
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