Re: Low Phase Noise 10 MHz bench signal source sought
On Sun, 03 Apr 2022 03:30:27 -0400, time-nuts-request@lists.febo.com
wrote:
time-nuts Digest, Vol 216, Issue 4
Multiple responses interspersed below.
Message: 5
Date: Sat, 2 Apr 2022 07:13:32 -0700
From: "Lux, Jim" jim@luxfamily.com
Subject: [time-nuts] Re: Low Phase Noise 10 MHz bench signal source
sought
To: time-nuts@lists.febo.com
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On 4/1/22 2:12 PM, Joseph Gwinn 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,
Ultimately, what you're looking for is a "oscillator and distribution
amp in a box with a power supply" - you can build it yourself, or you
can contract it out to a variety of places, or you can go to an
oscillator manufacturer.
Call Wenzel Associates (https://www.wenzel.com/) - they'll put some of
their low noise sources/distribution amps into a box with a power
supply. For a price. Their website is broken for these kinds of
products, but it's something they do all the time.
Yes.
Message: 16
Date: Sat, 2 Apr 2022 18:13:42 -0700
From: "Lux, Jim" jim@luxfamily.com
Subject: [time-nuts] Re: Low Phase Noise 10 MHz bench signal source
sought
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On 4/2/22 4:47 PM, Joseph Gwinn wrote:
On Sat, 02 Apr 2022 03:27:06 -0400, time-nuts-request@lists.febo.com
wrote:
time-nuts Digest, Vol 216, Issue 3
11. Re: Low Phase Noise70 10 MHz bench signal source sought
(Richard (Rick) Karlquist)
Date: Fri, 1 Apr 2022 19:12:07 -0700
From: "Richard (Rick) Karlquist" richard@karlquist.com
Subject: [time-nuts] Re: Low Phase Noise70 10 MHz bench signal source
sought
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com, Bob kb8tq kb8tq@n1k.org
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He [Joe] should be looking at Wenzel Associates and NEL.
Wenzel specs -170 dBc at 100 Hz offset.
I know of Wenzel, but they don't make bench-top lab instruments.
Rack-mount is available, but as a custom part.
Wenzel will be happy (for a price) to put it in any size or shape box
you want. Most people want rack mounts, but it's mostly a matter of
sheet metal work and they can certainly do that.
Yes.
Depending on your frequency and performance, you might find a "in
stock" oscillator. A 10 MHz Onyx or something like that might be
basically stock.
...
What is also needed is a very quiet source of DC power for the Rb,
OCXO, et al. None of the vendors seem to specify their PSRR (power
supply rejection ratio), and I assume that all published curves are
obtained using a battery-powered unit under test.
No, that's a "call them and ask", but most have pretty good PSRR
(although what are you looking for?) - the guy or gal on the phone will
tell you what it is in a "not guaranteed on the data sheet" sort of way.
Unless you want them to hit a spec, but you'll pay for it.
The basic requirement intent is simply to not undermine the
performance of the OCXO being powered.
https://wenzel.com/model/btuln/ mentions that they have an internal low
noise regulator - it's about 5dB shy of your -170 at 100Hz requirement.
This BTULN OCXO looks very good. While they do mention that it
contains its own regulator, no numbers are given, so it's hard to
know what to make of that claim.
I wouldn't assume battery power - but this is where a phone call helps -
they'll be happy to tell you.
I must say that I've run into the battery-power (or really good lab
power supply) approach, neither which is applicable in non-lab
applications. I suppose if Wenzel does the packaging, they will
ensure that full OCXO performance is achieved when powered from the
usual lab AC power. The box would also shield the power wiring and
frequency-control input (if any) and associated wiring from passing
EMI.
Joe Gwinn
Message: 17
Date: Sat, 02 Apr 2022 18:16:50 -0700
From: Hal Murray halmurray@sonic.net
Subject: [time-nuts] Re: Low Phase Noise70 10 MHz bench signal source
sought
To: Discussion of precise time and frequency measurement
time-nuts@lists.febo.com
Cc: Hal Murray halmurray@sonic.net
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richard@karlquist.com said:
The tester they used for ADEV consisted of a special 10811 that was 500 Hz
off frequency driving a dual mixer box (Model 10514?) which
produced a 500 Hz
beat note, which then drove an ADEV system (model 5490?). Only a
few of the
offset 10811's were produced due to the obvious disruption to the
production
line because of the offset frequency.
What can mortals do if they want a good reference oscillator with an offset?
Or maybe I should turn that around. How good can I get if I want
an offset?
And how do I do that?
--
These are my opinions. I hate spam.
On 4/7/22 3:09 PM, Joseph Gwinn wrote:
This BTULN OCXO looks very good. While they do mention that it
contains its own regulator, no numbers are given, so it's hard to
know what to make of that claim.
I wouldn't assume battery power - but this is where a phone call helps -
they'll be happy to tell you.
I must say that I've run into the battery-power (or really good lab
power supply) approach, neither which is applicable in non-lab
applications. I suppose if Wenzel does the packaging, they will
ensure that full OCXO performance is achieved when powered from the
usual lab AC power. The box would also shield the power wiring and
frequency-control input (if any) and associated wiring from passing
EMI.
Joe Gwinn
That's a "call Wenzel and ask" - They can answer your questions, and
all we can do is speculate. Even if I had a Wenzel box here in front of
me with test data, that doesn't mean YOUR Wenzel box would be the
same. And when it comes to "in the catalog, but really we have a
subset of stuff on the shelf" that's where calling is best. Who knows
what work they've been doing. They might have had a job to build half a
dozen sources, and they built 8, so that they'd have 6 guaranteed to
meet the requirements, and now they happen to have a spare, or a spare
that didn't quite hit -180, but only got -179. And you'd be happy with
that.
Wenzel is not some giant WalMart of oscillators, with forklifts going
hither and yon full of palletized ULNs - there are probably 50-60 people
there total, so odds are, you'll be talking to someone who actually has
touched (with gloves) your oscillator.
On 4/7/22 18:46, Lux, Jim wrote:
Wenzel is not some giant WalMart of oscillators, with forklifts going
hither and yon full of palletized ULNs - there are probably 50-60 people
there total, so odds are, you'll be talking to someone who actually has
touched (with gloves) your oscillator.
This is true. Wenzel is a small shop that really tries to be helpful.
For example, I've asked them for details on surplus oscillators that
have a custom part number. They won't give you data for that exact
part, but they'll nudge you to something that's very similar.
And while they're by no means cheap, a lot of their
multiplier/divider/buffer/PLL/etc. modules are not out of the reach of a
serious experimenter. They actually have things in their parts list
that are priced in three figures.
They're just good people.
John