On 4/2/22 4:47 PM, Joseph Gwinn wrote:
On Sat, 02 Apr 2022 03:27:06 -0400, time-nuts-requ...@lists.febo.com wrote: time-nuts Digest, Vol 216, Issue 311. 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" <rich...@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 <kb...@n1k.org> Message-ID: <0f524fb8-2220-635e-3f62-28f7f0816...@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.
501-04609.pdf
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