[time-nuts] Looking for datasheet for Oscilloquartz 8602

[Bob Camp]

Hi

The electronics in an SC based OCXO will be different from the "stuff" in an AT based part. At the very least you need additional traps for the SC. You also need to do something to accommodate it's significantly higher resistance. On the plus side, the SC probably can take 4X higher drive than the AT for a given amount of delta frequency / delta drive. Again, something that will impact the circuit. 

Far more significant than any of that - marketing may well have asked that the part be optimized in a different way so it would sell better. Phase noise often seen as a better "bragging rights" spec than ADEV. My personal opinion is that this bias is driven more by the fact that fewer people understand (or trust) ADEV and it's derivatives. 

Bob

On Jun 1, 2013, at 11:11 AM, Attila Kinali <attila at kinali.ch> wrote:

> On Wed, 29 May 2013 01:59:12 +0200
> Magnus Danielson <magnus at rubidium.dyndns.org> wrote:
> 
>> On 05/28/2013 07:55 PM, Attila Kinali wrote:
>> 
>> http://www.pttimeeting.org/archivemeetings/1984papers/Vol%2016_10.pdf
>> 
>> See also
>> http://www.pttimeeting.org/archivemeetings/1979papers/Vol%2011_25.pdf
> 
> Interesting stuff. Thanks a lot!
> 
>>> Juup. I just went back to Vig's tutorial and read up what he wrote.
>>> Misremembering things is not a good thing...
>>> But then, he explicitly writes that SC cut gives a higher stability
>>> over AT cut due to lower temperature dependence and less dips.
>> 
>> That is true, but your discreditation of AT-cut was simply way off the 
>> mark, so I wanted to bring it into context. There is a difference, but 
>> it is not as huge as it sounded like. I like to think about it as such 
>> that you better have done much of your homework in form of good 
>> oscillator and oven before considering spending money on going from 
>> AT-cut to SC-cut, but it does give that extra performance if you need 
>> it. The OSA 8600 shows just how far you can take AT-cut.
> 
> Oh.. Ok. Didn't want to sound that way. On the other hand, that conclusion
> is not far from the truth. I still have a lot to learn. Thanks for the
> correction.
> 
> But then, the 8600 has a ~10dB higher noise then the 8607. Ie the noise
> is 10 times higher (it is power-dB, not voltage-dB isn't it?). Which
> makes me wonder what the noise contribution is. I would assume that the
> electronics are very similar if not the same (electronics are cheap compared
> to the crystal) and the mechanical construction seems to be very similar
> as well.
> 
> In comparison the stability between 2 and 30s has only a factor of 2 inbetween.
> (maximum instability according to spec).
> 
> Any ideas what the reason could be?
> 
> 			Attila Kinali
> 
> -- 
> The trouble with you, Shev, is you don't say anything until you've saved
> up a whole truckload of damned heavy brick arguments and then you dump
> them all out and never look at the bleeding body mangled beneath the heap
> 		-- Tirin, The Dispossessed, U. Le Guin
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