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 <[email protected]> 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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