[time-nuts] Re: Low Phase Noise 10 MHz bench signal source sought
Bernd Neubig
BNeubig at t-online.de
Sun Apr 3 08:13:44 UTC 2022
Hi,
This is nearly "off-the shelf" model:
https://www.axtal.com/cms/docs/doc100916.pdf
The ULN version does meet the -170 dBc/Hz
Bernd
-----Ursprüngliche Nachricht-----
Von: Lux, Jim [mailto:jim at luxfamily.com]
Gesendet: Sonntag, 3. April 2022 03:14
An: time-nuts at lists.febo.com
Betreff: [time-nuts] Re: Low Phase Noise 10 MHz bench signal source sought
On 4/2/22 4:47 PM, Joseph Gwinn wrote:
> On Sat, 02 Apr 2022 03:27:06 -0400, time-nuts-request at 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 at 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 at lists.febo.com>, Bob kb8tq <kb8tq at n1k.org>
>> Message-ID: <0f524fb8-2220-635e-3f62-28f7f081665e at karlquist.com>
>> Content-Type: text/plain; charset=UTF-8; format=flowed
>>
>> 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.
>
> I did find NEL, and they do look very good. The NEL 2030A and 2030B,
> which are rack-mount, are plausible.
>
> Both are likely expensive, with long lead times.
My experience with Wenzel is that the cost isn't huge - the dominant thing will be the stuff that goes in the box (i.e. the oscillator). Essentially, you're paying for a few week's engineering and tech time to lay out and fab the thing. At 5-10k/work week, yes, you're looking at $10-20k for "the box and assembly" for a one-off.
I wouldn't have them put a $200 streamline OCXO in a box <grin>
If you're comfortable assembling the parts a linear supply from Acopian, a box, using frontpanelexpress.com to do the machining of the front and back panels, and the baseplate, and your oscillator. (that's what we've done at JPL on multiple occasions - although considering technician time it's probably cheaper to have Wenzel do it)
Wenzel also has a sort of intermediate level where you get a plate with a bunch of parts on it to do some function, and you put *that* in a box.
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.
>> If he is going to measure phase noise of another source with it,
>> he may need a VCOCXO to make a PLL.
> Yes, voltage control is also needed, so a Rubidium can be used to
> stabilize the OCXO. Or the OCXO already has that built in.
Most of them have an electronic tuning input. (which can be left out as
a special order).
My $200 (10 years ago) speedlines have a tuning input. Of course, it's
not hitting your -170 dBc requirement, but the ULN and other ones do (or
come close).
>
> 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.
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.
I wouldn't assume battery power - but this is where a phone call helps -
they'll be happy to tell you.
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