[time-nuts] Datum 4065A Cs Standard Info?

Ed Palmer ed_palmer at sasktel.net
Sun May 11 18:12:37 EDT 2014


Hi Magnus,

Yes, I've read a couple of documents on the process.  Basically they 
hold the OCXO EFC constant while they shift the DDS frequency around to 
make various measurements on the response curve to check the health of 
the tube, whether they're tuned to the right peak and that they're 
centered on the peak.  Adjusting the OCXO is almost a seperate process.  
Quite ingenious - when the DDS chip is working!

Since the chip replacement isn't going to happen quickly, I thought I'd 
spend some time exploring the system and learning what I can.  I even 
had the idea of breadboarding up a modulation scheme similar to the HP 
5061A just because it would be interesting to implement my own system.

Ed

On 5/11/2014 3:30 PM, Magnus Danielson wrote:
> Ed,
>
> On 05/11/2014 08:26 PM, Ed Palmer wrote:
>> I realize that this question has been asked before, but it's worth
>> asking again.  Has anyone come up with any technical info on any of the
>> 4065A or any of the other 4065 Cesium standards or the 5045A Cs Module
>> that it contains?  I have checked the archives and searched extensively
>> through Google.  I have the operating manual for the 4065C, but it looks
>> like it was OCR'd and not edited to correct typos so some of the info is
>> garbled so a new copy would be welcome.
>>
>> The immediate reason I'm looking for more info is that I noticed that
>> even when I replace the OCXO with a fixed 10 MHz, and the synthesizer
>> with a fixed 12.631... MHz signal, the system reports wildly varying
>> levels of beam current.  Nominal levels are 2500 +-500 ( I think -
>> that's one of the garbled parts), but I see levels from < 50 up to
>> 4000.  But I found the beam current monitor point and the level there is
>> stable.  So does this indicate another circuit fault, or is it just
>> because the system can't control the frequencies?
>
> I suspect that the processor gets fooled by the situation, so the fact 
> that you can't jump around cause all forms of levels that it compares 
> with incorrect.
>
> You want that DDS solution. This is a processor steered loop, and it 
> does a hell of a lot more than the old analog loops did.
>
> Read the patent, that should give you a hint of what it does.
>
> Cheers,
> Magnus




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