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

[Lux, Jim]

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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