[time-nuts] Question about SoundCard stability?
Bob Camp
lists at rtty.us
Wed Oct 13 11:11:32 UTC 2010
Hi
Should have been two out of three things ...
Bob
On Oct 13, 2010, at 6:58 AM, Bob Camp wrote:
> Hi
>
> Controller cycling is often a result of one of two things:
>
> 1) Resistance in the power lead
> 2) Extra insulation / dead air
> 3) Internal controller issues
>
> There are a few other possibilities, but they are remote enough that you are unlikely to ever come across them. There's no advantage to building a controller that's cycling. It was more likely a bug than a feature.
>
> Bob
>
>
> On Oct 13, 2010, at 4:00 AM, Magnus Danielson wrote:
>
>> On 10/13/2010 05:32 AM, Jim Lux wrote:
>>>
>>>
>>> On Oct 12, 2010, at 6:09 PM, Magnus Danielson<magnus at rubidium.dyndns.org> wrote:
>>>
>>>> Hi Bob and Dave,
>>>>
>>>> On 10/13/2010 02:57 AM, Bob Camp wrote:
>>>>> Hi
>>>>>
>>>>> Yes it is a reasonable expectation as long as you don't have a lot of drafts. A good TCXO can get down to sub 0.1 ppb over that period.
>>>>
>>>> This is why I like ADEV plots in datasheets. I rarely get to see them. TDEV plots is a nice complement naturally.
>>>>
>>>> Cheers,
>>>> Magnus
>>>>
>>>>> Bob
>>>>>
>>>
>>> And I wish there were adev plots for cheap tcxo's on the mgr data sheets
>>
>> Me too. I have to make the measurement myself. In one case I found that the oven control in one OCXO was unstable and had a resonance at about 7 second period. It was possible to measure it on the current supply too. The oven-control was having a relatively high-Q resonance and self-oscillation around the stability point. It increased the ADEV at that point to almost about 10 times more than expected. I learned that it was a good thing I measured it and yes, that spec didn't exist in the datasheet. It is unclear if they knew it or not. Even my half-crap setup proved valueable as I got aware of an issue on sample level rather than out in production phase.
>>
>> Cheers,
>> Magnus
>>
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>
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