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

[ghf at hoffmann-hochfrequenz.de]

I still have this idea to lock a flock of MTI-260 (which I have) to a
common Lucent-GPS, slooooowly to keep them as independent as possible,
but in-phase.

Say 8 or 16 pcs. The outputs would be Wilkinson-ed together, so 2**n
oscillators are preferred. The phase noise should average away.
That's what my VTOCXO ctl board was originally for. It can do much more,
like local 1pps that is not needed here.

Seems costly, but the last few dB are always costly. Should fit a 3H 19" 
box,
and the parts are available NOW and not next year.

And, a 9 or even 17-cornered hat, has that been done?

Gerhard,

who loves replicated simple electronics like my 220nV/rtHz amplifier 
with 20 * ADA4898.

Lockaflock (TM)  :-)




Am 2022-04-02 4:12, schrieb 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>
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