[time-nuts] 58503A alarm light on

Bob Camp kb8tq at n1k.org
Sat Apr 4 22:26:33 EDT 2015


Hi

If you watch the prediction number as the unit warms up, on some boxes it will go through a minima fairly early on. I’ve
seen it hit at a few days. I’m sure it depends a lot on how long the box has been off and the particular OCXO in the box. 
That prediction I do not believe at all. It goes away in < 12 hours….

The “you can believe it” sub 1us prediction seem to come after it’s been constantly on power for a while (like weeks). Again
how fast it gets there will vary unit to unit. 

All of that said, I don’t think I’ve seen any of mine hang out consistently above 2 us for any noticeable period of time after they have been
on a month or two. No, I don’t make a habit of constantly checking up on them….

Bob

> On Apr 4, 2015, at 8:21 PM, Charles Steinmetz <csteinmetz at yandex.com> wrote:
> 
> Bob wrote:
> 
>> I've seen the same sort of < 1 us holdover estimates out of mine as well.
>> I for one do *not* believe that it's going to do 200 ns holdover in 24 hours
> 
> No, nor do I.  But I do expect <1uS.  Mine seems to stay within <500nS over the first 24 hours with regularity, although I haven't tested it very often.
> 
>> the objective of the prediction function was to decide if it could
>> make 10 us over 24 hours
>>   *   *   *
>> In this case, a >11 us estimate says "I'm not going to make it". That means the
>> box is telling you it is not able to do what it should.
> 
> One expects a safety factor between the minimum spec and typical operation.  I'd be concerned if a 58503 was consistently predicting >2uS (to me, >2uS means "I may still meet spec, but I'm not as stable as I should be").
> 
> Best regards,
> 
> Charles
> 
> 
> 
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