[time-nuts] Re: Low Phase Noise70 10 MHz bench signal source sought

[Richard (Rick) Karlquist]

He should be looking at Wenzel Associates and NEL.
Wenzel specs -170 dBc at 100 Hz offset.  Hope he has lots of money for 
this one.  Some of the NEL OCXO's are $5,000 and 6 months to 1 year
delivery.  Both vendors also sell noisier cheaper versions.
He needs to trade off noise vs offset vs cost vs delivery time.

If he is going to measure phase noise of another source with it,
he may need a VCOCXO to make a PLL.

Rick N6RK

On 4/1/2022 4:57 PM, Bob kb8tq wrote:
> Hi
> 
> Rb and low phase noise ( at least far removed ) are sort of mutually
> exclusive specs. You need to pick one …
> 
> Assuming the decision is to go for the -170 dbc/Hz spec, Congratulations
> you are buying on OCXO. Not quite clear which OCXO, but it’s pretty likely
> to be an OCXO. (Yes, there are exceptions, but they are rare enough to be
> in the “don’t bother” category),
> 
> Next step would be to decide on the max offset that needs to cut in at.
> 100 Hz is into the “crazy/ not gonna happen” region. 1KHz is unlikely.
> 10 KHz is doable. 100 KHz relaxes things a bit.
> 
> While the “buy a bunch and test” approach works for things like ADEV,
> it probably isn’t the best approach for this spec. If you buy a bunch of this
> or that OCXO, their 10KHz phase noise *should* be pretty consistent.
> Sorting to get 2 db … nope, not worth it.  It *is* a pretty good bet that
> a commercial spec at 10K will be beat by 3 to 6 db.
> 
> What to buy? Head off to the spec sheets on whatever you see on eBay
> and make some guesses.
> 
> Bob
> 
> 
> 
> 
> 
>> On Apr 1, 2022, at 5:12 PM, Joseph Gwinn <joegwinn at comcast.net> wrote:
>>
>> I'm looking for suggestions for AC-powered 10 MHz sinewave laboratory
>> signal sources with very low phase noise, having a noise floor below
>> -170 dBc/Hz.  Rubidium is desired, but not essential.  Reliability
>> and durability in lab use is essential.
>>
>> Which makes and models should I consider purchasing?
>>
>> I like the SRS model FS725, but its noise floor is too high at -150
>> dBm/Hz, 20 dB noisier than many things I may wish to measure.
>> <https://www.thinksrs.com/products/FS725.htm>
>>
>> Thanks,
>>
>> Joe Gwinn
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