[time-nuts] How to create a super Rb standard

[Javier Herrero]

Hello,

And about temperature, in this article 
http://www.dtic.mil/dtic/tr/fulltext/u2/a495520.pdf there is an 
interesting point, in the last page: Riley answer to the question "You 
mentioned larger cells. Where there any other things done go get these 
fantastic results?

Regards,

Javier

On 18/01/2017 13:12, Bob Camp wrote:
> Hi
>
> You would need to redesign the Rb to work in a vacuum. There is a lot involved
> in doing that. They depend on the air inside the package to properly operate the
> heating in the physics package. Different parts of the package are at different
> temperatures. Without the air cooling the temperature offsets could not be properly
> maintained.
>
> There are a *lot* of differences between the GPS Rb’s and the ones we buy on
> eBay. The fact that they operate in pretty far down the list of significant differences.
> The most simple answer to “why” the Rb is better is that the design requirements
> on the two standards were different, as were the design teams. Coming up with
> an Rb with better short term stability is the way that all worked out. That short
> term stability is better than other large cell Rb designs, but not by a crazy amount.
> How much better it is depends a lot on which large cell Rb design you compare to.
> It also depends a bit on which specific unit you are looking at.
>
> All that said, space benign is indeed a pretty quiet environment. It certainly does
> help a bit if you operate there. There is also data on the GPS Rb’s that show them
> doing quite well on the ground. So no, it’s not all space, but space does not hurt
> their performance.
>
> Bob
>
>> On Jan 18, 2017, at 12:23 AM, Li Ang <379998 at qq.com> wrote:
>>
>> Hi
>> I am wondering if anyone tried to put a Rb unit into a vacuum container. And how much the performance is improved? Someone told me that's why the Rb clocks are more stable than Cs clocks on the GPS satellites.
>>
>> LiAng
>>
>> ---Original---
>> From: "Bob Camp"<kb8tq at n1k.org>
>> Date: 2017/1/17 21:20:23
>> To: "Discussion of precise time and frequency measurement"<time-nuts at febo.com>;"Perry Sandeen"<sandeenpa at yahoo.com>;
>> Subject: Re: [time-nuts] How to create a super Rb standard
>>
>>
>> Hi
>>
>> Since the physics package in the small Rb’s is different than the stuff in the large units,
>> you have some basic limits on what you can do to improve them. The main things people
>> have done are to modify them to turn off the temperature compensation and replace it
>> with some sort of precision controlled thermal enclosure. Pressure compensation is a good
>> idea on any of these parts (large or small). How much your particular unit benefits is a
>> “that depends” sort of thing.
>>
>> Bob
>>
>>> On Jan 16, 2017, at 10:24 PM, Perry Sandeen via time-nuts <time-nuts at febo.com> wrote:
>>>
>>>
>>> List
>>> It looks like their is as infinitely small chance of being able to get 5065.
>>> So what can be done with the telco Rb's (mine are analog tuned) to wring the best possible performance from them? Sooper Duper power supplies, Peltier (sp) cooling modules?
>>> Regards,
>>> Perrier
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