[time-nuts] Synchronisation of crystal oscillators

[Bob kb8tq]

Hi

To “see” the zero beat, they have to be hooked to some sort of test gear. 
It’s only going to have just so much isolation. 

The fine old 3048 phase noise test set was pretty good at injection locking
the devices you were testing ….

Loaded Q on a “typical” 10 MHz OCXO is likely in the 500K range. Yes it 
depends on the circuit and the crystal. That gets the 3db bandwidth out 
into the ppm range. If you are getting anywhere near zero beat, you are
*well* within the 3db bandwidth.

Bob

> On Mar 10, 2020, at 9:35 PM, Robert DiRosario <ka3zyx at comcast.net> wrote:
> 
> >  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
>> 
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at lists.febo.com
>> To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
>> and follow the instructions there.
>> 
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at lists.febo.com
> To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.