[time-nuts] Synchronisation of crystal oscillators

[Robert DiRosario]

 >  OTOH, if you carefully
 >adjust a couple of HP10811's to zero beat, you will have to
 >go to extraordinary measures to keep them from injection locking.
 >A lot more than just running them on individual voltage
 >regulators.

How are they connected, or coupled?  They seem to be well shielded, do 
you tie the
outputs together?  Don't they have a transistor buffer stage on the output?

Robert


On 03/01/2020 05:46 PM, Richard (Rick) Karlquist wrote:
>
>
> On 3/1/2020 2:28 PM, John Moran, Scawby Design wrote:
>> My apologies if this is slightly off-topic, but it does concern 
>> crystal oscillators.
>>
>>> However, I then remembered Huygens's discovery that 1S pendulums 
>>> mounted on the same wall, or beam, would synchronise and swing 
>>> either in phase, or out of phase and sometimes one would be stopped, 
>>> by the minute interactions.
>>
>> So, my question is - will my row of low frequency crystals 'talk' to 
>> each other and synchronise in their frequency groups as well? 
>> Remember that these crystals are long thin bars of quartz - one of 
>> the 3,600Hz crystals being 2mm square by 60mm long - so they will 
>> possibly vibrate quite vigorously compared w
>
> Injection locking requires that the oscillators be within each
> others 3 dB bandwidth, or at least close to that.  Oscillators
> on different nominal frequencies are no problem (EG 3 MHz and
> 10 MHz).  Even two "10 MHz" oscillators won't lock unless they
> are adjusted to close to zero beat.  OTOH, if you carefully
> adjust a couple of HP10811's to zero beat, you will have to
> go to extraordinary measures to keep them from injection locking.
> A lot more than just running them on individual voltage
> regulators.
>
> Bottom line: probably not worth worrying about for your
> hobby project.
>
> Rick N6RK
>
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