[time-nuts] Adjusting HP 5065A frequency

Sun Oct 21 16:40:18 UTC 2012

Dear John,

Thank you for your kind comments. May I assume that a temperature controlled environment for the 5065A is one similar to a data center with A/C? Or a room without A/C but keeping a minimum temperature variation? Perhaps +/- 5º C/F?

My small lab shares the space with my ham shack. No A/C there.  A couple of computers idling 24x7 plus the clocks running warm tend to keep temperature around 22ºC/71.5ºF as I have seen from my WX station. Is it better to keep the clocks ticking in a warm environment? Or should I go the IT route and installing a mini-split type A/C unit to keep the temperature lower? My lab area is small as well as heat generation, so I assume that one of the smaller A/C units could do the job.

IMHO if the oscillators are of the oven controlled type, are the temperature effects related to the electronics inside the frequency standards?

Finally, could you please point out some of the information you mention regarding the temperature variation and the 5065A?

Thank you.

Regards,

Edgardo Molina
Dirección IPTEL

www.iptel.net.mx

T : 55 55 55202444
M : 04455 20501854

Piensa en Bits SA de CV

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On Oct 21, 2012, at 10:58 AM, John Ackermann   N8UR <jra at febo.com> wrote:

> Hi Edgardo --
> 
> One slightly frustrating thing about the 5065A is that its frequency settability isn't as good as its short term stability.  I believe the manual says that the small divisions on the C-field counter dial are 2x10e12, and it's hard to set closer than that.
> 
> A good 5065A is a remarkable piece of gear, with medium term stability over, say, 1K to 100K seconds that is very hard to beat by anything other than a maser.  As best I can measure mine against a number of other sources (no maser here, sigh), it is around 1e13, maybe a bit better, over that range.  That's an order of magnitude better than any of the telco Rbs.
> 
> This is just a guess, but from some data that tvb and others have reported, I suspect that external tempco is the main limiter for medium term stability in the 5065A.  It would be interesting to see one in a temperature-controlled environment vs. one that's not.
> 
> John
> 
> On Oct 21, 2012, at 11:11 AM, Edgardo Molina <xe1xus at amsat.org> wrote:
> 
>> Dear Corby,
>> 
>> Good morning. Thank you for the detailed instructions to bring the 5065A close to desired frequency. I couldn't have a cleaner explanation of the process. 
>> 
>> Yesterday evening I tried adjusting the C field in small steps using a mixer, lpf and two oscillators setup as my current frequency counter is not able to resolve de small increments/decrements of frequency adjustment. Still I could detect the adjustments as I performed them. The response is quite fast. I have been told that these units are really stable compared to the small telecom Rb units. I heard a comment that the 5065A is even more stable than the new Symmetricom units using the X72 Rb module. Have you ever measured such differences in stability?
>> 
>> Thank you.
>> 
>> Regards,
>> 
>> 
>> 
>> 
>> Edgardo Molina
>> Dirección IPTEL
>> 
>> www.iptel.net.mx
>> 
>> T : 55 55 55202444
>> M : 04455 20501854
>> 
>> Piensa en Bits SA de CV
>> 
>> 
>> 
>> Información anexa:
>> 
>> 
>> 
>> 
>> CONFIDENCIALIDAD DE INFORMACION
>> 
>> Este mensaje tiene carácter confidencial. Si usted no es el destinarario de este mensaje, le suplicamos se lo notifique al remitente mediante un correo electrónico y que borre el presente mensaje y sus anexos de su computadora sin retener una copia de los mismos. Queda estrictamente prohibido copiar este mensaje o hacer usode el para cualquier propósito o divulgar su en forma parcial o total su contenido. Gracias.
>> 
>> 
>> NON-DISCLOSURE OF INFORMATION
>> 
>> This email is strictly confidential and may also be privileged. If you are not the intended recipient please immediately advise the sender by replying to this e-mail and then deleting the message and its attachments from your computer without keeping a copy. It is strictly forbidden to copy it or use it for any purpose or disclose its contents to any third party. Thank you.
>> 
>> 
>> 
>> 
>> 
>> On Oct 19, 2012, at 5:55 PM, cdelect at juno.com wrote:
>> 
>>> Edgardo,
>>> 
>>> You do use the C-field adjust to put a 5065A "On frequency". The Factory
>>> values are a moot point after all these years!
>>> 
>>> Just incrementaly adjust the c-field control in small steps while
>>> observing the frequency comparison. 
>>> 
>>> The only thing that might happen is that you reach one end of the C-field
>>> pot before getting to the frequency you want.
>>> 
>>> If that is the case you will need to set the synthesizer switch to the
>>> next value in the chart. (either up or down depending on which way you
>>> ran out of room.)
>>> 
>>> Then start over with the c=field adjustment.
>>> 
>>> If you switch the synthesizer setting you will need to remove power
>>> momentarily to reset the synthesizers lock indication circuit. Otherwise
>>> pushing the logic reset button to get the green light wont work.
>>> 
>>> Corby
>>> ____________________________________________________________
>>> Woman is 53 But Looks 25
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