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Tr: K3 Ref connector

Craig-89

Hi

Talking about rubidium standards.

Does anyone have any experience with buying and using the EFRATOM LPRO-101 rubidium standard that  seems to be readily available from  the many Chinese sellers on Ebay?

I am tossing up between the LPRO rubidium  and the Thunderbolt GPS standard. The Thunderbolt  makes a lot of sense since it  does  not depend on a tube that can wear out or go out of lock.

Will Elecraft be producing both the frequency standard and the interface or just the interface?

73
Craig


     
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Re: Tr: K3 Ref connector

David Pratt
In a recent message, Craig <[hidden email]> wrote ...
>
>I am tossing up between the LPRO rubidium  and the Thunderbolt GPS
>standard. The Thunderbolt  makes a lot of sense since it  does  not
>depend on a tube that can wear out or go out of lock.

True, but it does assume that the GPS satellites will not be wiped out
by a chain reaction caused by the conglomeration of space junk up there.

>Will Elecraft be producing both the frequency standard and the
>interface or just the interface?

I doubt that Elecraft will need to supply a standard as there already
exists several sources of those.  We must be thankful of their intention
to provide the KREF3-EXT interface.

73
--
David G4DMP
Leeds, England, UK
------


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Re: Tr: K3 Ref connector

n7ws
In reply to this post by Craig-89

I guess I'm missing the reason for having such precision. How can it make sense to have a precision standard for a receiver that changes the tuned frequency when the DSP bandwidth is changed?

Wes  N7WS

--- On Sat, 5/16/09, Craig <[hidden email]> wrote:

> From: Craig <[hidden email]>
> Subject: [Elecraft] Tr: K3 Ref connector
> To: [hidden email]
> Date: Saturday, May 16, 2009, 3:14 AM
>
> Hi
>
> Talking about rubidium standards.
>
> Does anyone have any experience with buying and using the
> EFRATOM LPRO-101 rubidium standard that  seems to be
> readily available from  the many Chinese sellers on
> Ebay?
>
> I am tossing up between the LPRO rubidium  and the
> Thunderbolt GPS standard. The Thunderbolt  makes a lot
> of sense since it  does  not depend on a tube that
> can wear out or go out of lock.
>
> Will Elecraft be producing both the frequency standard and
> the interface or just the interface?
>
> 73
> Craig
>
>
>      
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>


     
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Re: Tr: K3 Ref connector

David Cutter
In reply to this post by David Pratt
I wonder if there is a way of using a cheap 60kHz radio controlled clock
receiver to phase lock an 'ordinary' 10MHz crystal osc.

David
G3UNA


-----

> In a recent message, Craig <[hidden email]> wrote ...
>>
>>I am tossing up between the LPRO rubidium  and the Thunderbolt GPS
>>standard. The Thunderbolt  makes a lot of sense since it  does  not
>>depend on a tube that can wear out or go out of lock.
>
> True, but it does assume that the GPS satellites will not be wiped out
> by a chain reaction caused by the conglomeration of space junk up there.
>
>>Will Elecraft be producing both the frequency standard and the
>>interface or just the interface?
>
> I doubt that Elecraft will need to supply a standard as there already
> exists several sources of those.  We must be thankful of their intention
> to provide the KREF3-EXT interface.
>
> 73
> --
> David G4DMP
> Leeds, England, UK
> ------
>
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Re: Tr: K3 Ref connector

Leigh L. Klotz Jr WA5ZNU
Administrator
In reply to this post by Craig-89
I have bought items from fluke.l on eBay who sells them. He sells the
GPS-DO, the Efratom device, adn the one I bought which is an FE-5860A
Rubidium frequency standard from him and hooked it up last night. I've
found fluke.l to be responsive and honest, and he ships quickly. (If you
are in a hurry, ask about shipping options.)

Here is a report on what I've learned and done so far, and where to find
more info, plus a few rants on what I'd like to do myself.

If nothing else, I've been annoying my family and co-workers by saying
things like, "Let me get back to you on that after I finish the
modifications I'm making to my Rubidium atomic clock." So, if you really
want to know about these, don't listen to me, but instead look at these
resources:
1. There's a mailing list called time-nuts where people who actually
understand them hang out, and
2. Connie http://www.k5cm.com/ runs a monthly frequency measuring test
and they have a mailing list there as well. (I placed fairly high in the
last ARRL FMT, though not at the top.)
3. If you order an FE-5680A, this page is very useful:
http://www.dd1us.de/Downloads/precise%20reference%20frequency%20rev%200_4.pdf

Here's what I've learned from the manuals and reference materials:
A Rubidium reference oscillator uses a Rubidium bulb, which is heated
and the resulting gas tested for light absorption in the presence of an
external RF field in the 6 GHz range. The microwave signal is tuned in a
feedback loop to look for the peak in absorption (a very small change on
the order of 0.1%) and that locks the oscillator in the known frequency
of 6 834 682 610.904 324 Hz. Another external field is used to change
this slightly, but I'm not the person to explain the physics. A 136x
divider brings this down to 50.566+ Mhz, so you wind up with what is
essentially a very stable oscillator with low phase noise. This 50+Mhz
signal is then used as the reference frequency for our old friend the
AD9830A DDS chip, which can then be programmed via an internal
microprocessor and RS232 to whatever frequency you want, within the
Nyquist range and the output filter range. By default these come set for
~8Mhz (2^23 Hz, which is divided down to get a 1Hz output).

In most of the surplus units, this signal isn't available externally,
but only internally with a connector that looks like a Hirose U.Fl
connector. (If anybody knows different, please let me know, as I already
have a U.Fl to BNC bulkhead pigtail on order.)

I used the default 8,388,608 Hz signal out to a test pin to calibrate my
FCC-1 kit, which it turned out was already within 1Hz.
I also tried using it to calibrate my K3 REF CAL, but I'd turned the K3
off earlier and it wasn't warmed up.

What I'd like to do: once my connector pigtail arrives, I'll put it in
the FE-5860A and make a stab a quick python program to read the
frequency with fldigi's in Freq Cal mode and read the data from fldigi's
remote XML interface and use the K3 RS232 to control the REF CAL
setting. Of course, this hack would just automate a manual process, and
doesn't provide a way to keep the K3 on frequency during TX.

Leigh/WA5ZNU


> Hi
>
> Talking about rubidium standards.
>
> Does anyone have any experience with buying and using the EFRATOM LPRO-101 rubidium standard that  seems to be readily available from  the many Chinese sellers on Ebay?
>
> I am tossing up between the LPRO rubidium  and the Thunderbolt GPS standard. The Thunderbolt  makes a lot of sense since it  does  not depend on a tube that can wear out or go out of lock.
>
> Will Elecraft be producing both the frequency standard and the interface or just the interface?
>
> 73
> Craig
>
>
>      
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>  

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