[time-nuts] Re: Coupling between oscillators -- an example

[Bob kb8tq]

Hi

Even in a commercial environment where one would *think* that 
all the issues had been spotted and worked out long ago, issues 
like this pop up pretty often. Any time you take this sort of data, 
you very much need to look at what’s going on and see if it makes 
sense.

If there was a “one size fits all” solution to precision measurement, 
this all would be a lot easier. If that answer is out there, nobody 
seems to have found it yet. What works over here may be what’s
causing the problem over there ….. 

Bob

> On Mar 25, 2022, at 9:39 PM, John Ackermann N8UR <jra at febo.com> wrote:
> 
> 
> On 3/25/22 19:22, ed breya wrote:
> 
>> I'm a firm believer in using signal isolation transformers where needed and practical. I've had plenty of issues with ground loop interference - usually from line frequency harmonics - especially between different pieces of equipment, but it can show up internally too.
> 
> It seems like isolation transformers are a coin toss between helping, doing nothing, and sometimes actually making things worse.  I think the problem is there are so many possible ground paths via power wiring, or even chassis bolted to racks, that one size very much doesn't fit all.
> 
> Another interesting thing is that this situation was easy to spot because of the significant frequency differences that made the beat period fairly short.  If these guys had all been within 1e-10 of each other, the trouble might have been harder to spot.
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