[time-nuts] CSAC Project(was CSAC purchase)

Bob kb8tq kb8tq at n1k.org
Thu Jan 25 15:42:02 EST 2018


Just to be clear, the current data sheet has the temperature range back to 
-10 to +70C. They most certainly had a major headache on their hands for
several years straightening things out. I have not seen any complaints about
the “new” (post rework) version of the part. 


> On Jan 25, 2018, at 3:31 PM, jimlux <jimlux at earthlink.net> wrote:
> On 1/25/18 9:39 AM, gandalfg8--- via time-nuts wrote:
>> At the time of writing a copy is available here....
>> www.obsip.org/documents/Gardner_IEEE_Oceans_2016.pdf
> "While results from an early batch of CSACs have been largely positive, later units have not performed as well. The CSAC specifications have changed, reflecting a decrease in reliability and accuracy of more recent units."
> no kidding - there's a well known issue when MicroSemi took over building CSACs from Symmetricom, these things (like many precision timing widgets) have a "recipe" and it's easy to "lose the recipe" or find that there's unexpected and unknown components to the recipe.
> Take a look at data sheet revs for the CSAC.. full temp range, then all of a sudden around rev G or H, temperature range is quoted at 0-35C operating, *0-40C non-op*.  I asked the sales rep if they ship them with icepacks in styrofoam like mail order cheese in the summer - that UPS truck gets way over 40C inside.
> As always, this was discussed on the list and is in the archives.
> That being said, I have no complaints about Microsemi being forthcoming about the issue and helping us to understand the nature of the problem. And they claim to have fixed the problem.
> Hopefully, this summer, I'll have some data from a "narrow temp range" CSAC against GPS 1pps in an environment where there's no gravitational effects, and fairly small temperature fluctuations.
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