Indeed, now I see it. As we expect around +10 dBm, the noise-floor might be raised by about 20 dB.

I was more considering what is the reference noise here, is there a single oscillator as reference? Can a quieter reference oscillator be used? Can a cross-correlation setup be done?


Cheers,
Magnus

On 09/18/2016 01:52 PM, Bruce Griffiths wrote:
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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