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The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator
The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator
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Old 10th June 2021, 09:18 PM   #3871
wlowes is offline wlowes  Canada
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IMHO you will not pay a penalty for RG178 over RG400 that is worth worrying about. But when you sit to listen critically, you may appreciate wrenched down SMA connectors.

Last edited by wlowes; 10th June 2021 at 09:20 PM.
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Old 10th June 2021, 09:28 PM   #3872
eduard is offline eduard  Netherlands
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Hello,

I just copied and paste an old post of mine from a month ago i think.
Hello,
SO the way the clocks and the associated circuitry are '' housed '' is a key element in the final result.
I found a 50 mm thick pressed cork panel that i will use to make a kind of sound proof box to isolate the 6 aluminium rectangles.
My intention is to put the supercap in the attachment in between the two trinities and give each unit its own connection to the supercap terminal. SO there will be just one power cable entering the soundproof box. I think giving each unit a cable coming from the outside will/could introduce more vibrations from outside.
In between the 6 rectangles the cork does not have to be as thick.
Of course the boards are '' interconnected '' by the rather rigid coaxial cable. If the circuit is kind of fixed to the frontpanel by the terminal for this cable lots of vibration reducing elements are kind of abolished.
So i think the best idea to wrap all the boards in( carbon foam/ natural fiber????), makes the coaxial connections and slide the boards inside the tube.
If you slide them deeper into the rectangle will the opening on the front have less influence. Of course it will be easy to cover the opening and just leave an opening for the DC supply and the coaxial cables.
I am sure some of these things can be ''determined '' by specific knowledge, most could be measured.
There is a variety of thing you can do to stop the clock from vibrating. The easiest thing is stopping the airborn vibration. And use tin wires to connects the clock to the board is very clever. BUT once there is a kind of firm connection between the SMA terminal and the case( probably you could use a wire between terminal and case to create a prper connection) plus there will be a sturdy cable picking up airborne vibrations and transporting vibrations from one chassis do the other.
It will be like in the old days when people started using garden hose seize cables from their tonearms to their phonostages which would almost destroy all the nice anti feedback ideas in their expensive turntables.
There should me more exchanges of ideas how to handle things like this but it seems also customers find greater joy in getting the latest boards while their old boards never have been used in a proper way.
Greetings, eduard
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Old 11th June 2021, 01:19 AM   #3873
gerhard is offline gerhard  Germany
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Quote:
Originally Posted by Joseph K View Post
The DUT was an LT3042/ LT3094 dual reg, made by ourselves. The signal is taken from the regulated DC output, 4,5V, cca 60mA load.
The setup was: Cookie can >battery> reg. board> Gerhard 's 20x4898 pre at 60dB gain > RTX6001 > HPWorks
Try a 4700u / >=25V wet slug tantalum for the pre input and you
get rid of the 30 dB / decade noise rise. And be careful then not to
Zener the op amp inputs. With some luck a good alu elctrolytic might do.

Gerhard
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Last edited by gerhard; 11th June 2021 at 01:27 AM.
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Old 11th June 2021, 01:36 AM   #3874
1audio is offline 1audio  United States
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The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator
The SMA connections are supposed to be torques to 5 in/lb. You can buy $$$ torque limiting wrenches for that purpose, which I would do if its a critical connection to a MM wave system.
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Old 11th June 2021, 02:00 AM   #3875
wlowes is offline wlowes  Canada
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Great suggestion. Thanks Demian
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Old 11th June 2021, 03:37 AM   #3876
1audio is offline 1audio  United States
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The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator
Some of the options are ridiculously expensive- A used HUBER+SUHNER for $100? They are not that exotic. However if you are working with 60 GHz 1.85 mm connectors it would make sense.
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Old 11th June 2021, 05:59 AM   #3877
syn08 is offline syn08  Canada
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Quote:
Originally Posted by Joseph K View Post
I have done that, too!!
With LT3042, Ref bypass cap X7R.
Then changed Ref bypass to PPS, REF resistance to an S102. Then played a multitone signal from like 20cm distance.
First shot is 'standard', second shot is LT3042 'deadened'
What multitone was that? The spikes appear to be even multiples of 50Hz (mains frequency in yours and your we country.
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Old 11th June 2021, 07:01 AM   #3878
gentlevoice is offline gentlevoice  Denmark
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The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator
@gerhard & 1audio:

Thanks both for your spectrum analyzer comments ... and since this is a digression to the TWTMC thread just briefly: I think the Red Pitaya and the tinySA both look interesting, however, their basic noise levels appear to be quite high so that what I am looking for may be hidden in the noise. The Red Pitaya is very versatile though ...

The SignalHound on the other hand looks "remarkable" (from my new-to-SA perspective) - 124 dBm basic noise level at 10 Hz and getting better going up in frequency. Could be interesting as well ...

Good suggestions! & clarified about the Timepod in the SA context ...

Thanks again both of you ;-)

Jesper
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Old 11th June 2021, 08:45 AM   #3879
Joseph K is offline Joseph K  Hungary
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Quote:
Originally Posted by syn08 View Post
What multitone was that? The spikes appear to be even multiples of 50Hz (mains frequency in yours and your we country.
It is the "Speech" range multitone signal from Arta. And yes, it starts like
"Linearly spaced sine signals from 100 Hz to 500 Hz, plus 1/3 octave
spaced sine signals from 500 Hz to 8 kHz. Phases optimized for crest
factor 10  1 dB."
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Old 11th June 2021, 12:50 PM   #3880
Markw4 is offline Markw4  United States
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@Thom

Images you have attached to your posts appear to me as shown below. If I right click on one of the links to open it in a new tab, I am asked for Google Drive logon credentials.

Perhaps if you add the images to your posts as file attachments (using Advanced mode), they could be viewable by more of us
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File Type: jpg Thom.jpg (127.5 KB, 113 views)
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