[time-nuts] Realistic Tbolt phase noise

[Christophe Huygens]

Hi,

I am using an ADF4107 and a Crystek resonator, with a LBW of
a few 100 Hz. It behaves perfect outside the loop, but inside the
loop it is too noisy (not too important for my application, but
just curious).

I ll try to measure the Thunderbolt directly at 10Mhz, but the
my HP 11729C needs some mods for this.

Christophe


On 09/03/10 18:21, Bob Camp wrote:
> Hi
>
> How are you multiplying it to 1 GHz and checking it?
>
> I've seen multipliers that have issues beyond about -130 at 100 Hz. It's not
> common, but it can happen.
>
> ------------------
>
> The supply provided by TAPR is a pretty basic unit. It would not surprise me
> if some were better than others. They also may work better on US mains
> voltage than they do on international voltages. I would rig up another
> supply and see what happens. That would at least rule out the supply as an
> issue.
>
> In a previous post the idea of putting a 7805 and 7812 regulator on the
> TBolt came up. If you have +14 available that seems like the best thing to
> try.
>
> Bob
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Christophe Huygens
> Sent: Tuesday, March 09, 2010 7:50 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Realistic Tbolt phase noise
>
> This is with the power supply as provided by TAPR so should be ok.
>
> Xtof.
>
>
> On 09/03/10 13:44, Bob Camp wrote:
>    
>> Hi
>>
>> Power supply noise would be the first thought.
>>
>> Next up would be grounding inside the Thunderbolt (card to case,
>>      
> connectors to case).
>    
>> Bob
>>
>>
>> On Mar 9, 2010, at 7:32 AM, Christophe Huygens wrote:
>>
>>
>>      
>>> Hi,
>>>
>>> I noticed several vendors on Ebay have the t-bolt on sale.
>>>
>>> However, the once showing their own PN plots seem to get only
>>> -115, -120 dBc/Hz at 100Hz. Yet,
>>> http://www.leapsecond.com/pages/tbolt/noise.htm seems
>>> to have mucht better results: up to -150 depending on
>>> power supply.
>>>
>>> By multiplying to 1GHz I also seem to be getting something
>>> like -75 or - 80 rather than -110.
>>>
>>> Any thoughts?
>>>
>>> Christophe
>>> on4iy
>>>
>>>
>>>
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