Re: [time-nuts] Synchronisation of crystal oscillators

Since the answer to my original question of possible synchronisation was a reasonably resounding no, I started doing some design work and then got an off-post message from TVB suggesting the use of his neat PicDiv chips to divide all my crystals down to 1PPS. On ordering a batch he came up

Re: [time-nuts] Synchronisation of crystal oscillators

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

Re: [time-nuts] Synchronisation of crystal oscillators

> 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

Re: [time-nuts] Synchronisation of crystal oscillators

Hi, On 2020-03-02 03:53, Richard (Rick) Karlquist wrote: > > > On 3/1/2020 5:58 PM, Alex Pummer wrote: >> don't forget the  oscillator is one amplifier with infinite gain on >> his own frequency >> 73 >> KJ6UHN >> Alex >> > > Actually, the closed loop gain is not infinite, rather it is whatever

Re: [time-nuts] Synchronisation of crystal oscillators

On 3/1/2020 5:58 PM, Alex Pummer wrote: don't forget the  oscillator is one amplifier with infinite gain on his own frequency 73 KJ6UHN Alex Actually, the closed loop gain is not infinite, rather it is whatever is needed to boost thermal noise enough to account for the RF output level. I

Re: [time-nuts] Synchronisation of crystal oscillators

Hi Well, there goes Barkhausen …. :) https://en.wikipedia.org/wiki/Barkhausen_stability_criterion Bob > On Mar 1, 2020, at 8:58 PM, Alex Pummer wrote: > > don't forget the oscillator is one amplifier with infinite gain on his

Re: [time-nuts] Synchronisation of crystal oscillators

don't forget the  oscillator is one amplifier with infinite gain on his own frequency 73 KJ6UHN Alex On 3/1/2020 2:46 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

Re: [time-nuts] Synchronisation of crystal oscillators

Yes, oscillators that are harmonically related can indeed injection lock. I've done it in a project about 40 years ago. In your case, you need to avoid RF cross-coupling between the oscillators. This includes both electromagnetic coupling, "direct coupling" via use of a common power supply, and

Re: [time-nuts] Synchronisation of crystal oscillators

On 3/1/2020 3:03 PM, Hal Murray 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 How extraordinary? How likely are 2 GPSDOs

Re: [time-nuts] Synchronisation of crystal oscillators

rich...@karlquist.com said: > 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). Will oscillators on integral multiples of some frequency lock?

Re: [time-nuts] Synchronisation of crystal oscillators

> 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

Re: [time-nuts] Synchronisation of crystal oscillators

Hi The correct answer is “that depends”. The quick answer is “probably will”. It depends on the Q of the parts (which likely is pretty low), the coupling (which will be pretty good), and the exact frequency of each unit (which is unknown). Setups like this have been known to lock up. Bob >

Re: [time-nuts] Synchronisation of crystal oscillators

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

[time-nuts] Synchronisation of crystal oscillators

My apologies if this is slightly off-topic, but it does concern crystal oscillators. I have a small collection of ancient crystals amassed over the past 50 years or so. Half a dozen are low frequency (3,600Hz, 10kHz, and 100kHz), long bar, crystals sealed into B7G vacuum tube bodies. I was