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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 29th March 2015, 08:45 PM   #521
Zoran is offline Zoran  Serbia
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Andrea what abour "owenized" boards? Did You try maybe?
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Old 29th March 2015, 10:06 PM   #522
andrea_mori is offline andrea_mori  Italy
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The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator
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Originally Posted by Zoran View Post
Andrea what abour "owenized" boards? Did You try maybe?
I'm looking for a suitable copper oval tube to solder to the board and fits the crystal (internal size 3.5mmx10mm, wall thickness <1mm), then I'll order the PCB heater prototype.
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Old 5th April 2015, 07:16 AM   #523
justubes is offline justubes  Singapore
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Hi Andre,

How does the 1st MO crystal measure at 1hz (phase noise) or compare with the crystek crystals?

I am rather lost on the ocxo's, thee are not drop in and how do we implement it into a vcxo circuit? A board (PLL?) Is need to covert the ocxo sine wave output to squarewave before it is used, if i am correct. I presume that implementationof the ocxo will have better phase noise than the drop in crystals?

These boards are still in progress before confimation can be made that it's a go with the ocxo, interested! so a power supply for the ocxo heater and PLL has tp be added in order for the ocxo to work.

Will a circuit be reserved that allows a 10m reference be included for the next stage project after the ocxo?

Last edited by justubes; 5th April 2015 at 07:24 AM.
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Old 5th April 2015, 12:33 PM   #524
andrea_mori is offline andrea_mori  Italy
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The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator
Quote:
Originally Posted by justubes View Post
Hi Andre,

How does the 1st MO crystal measure at 1hz (phase noise) or compare with the crystek crystals?

I am rather lost on the ocxo's, thee are not drop in and how do we implement it into a vcxo circuit? A board (PLL?) Is need to covert the ocxo sine wave output to squarewave before it is used, if i am correct. I presume that implementationof the ocxo will have better phase noise than the drop in crystals?

These boards are still in progress before confimation can be made that it's a go with the ocxo, interested! so a power supply for the ocxo heater and PLL has tp be added in order for the ocxo to work.

Will a circuit be reserved that allows a 10m reference be included for the next stage project after the ocxo?
I have not yet measured the phase noise of the Colpitts-Clapp oscillator. As I said, I have limited access to a university lab, so I will measure all the 3 oscillators (Clapp, Butler and Driscoll) when they will be all ready. For now you can refer to the plot I posted in #5, where the the Clapp oscillator was measured using a similar crystal.

About the SC-cut crystal, I'll not provide any PLL. These crystals could be also used in the Clapp oscillator, while I'll start experimenting soon with Butler 2 emitters and Driscoll oscillators, more suitable for high Q crystals, since the crystal sees a very low impedance, that means very high loaded Q.

Next weeks I'll order the crystal heater PCB (#515). It could be used with all the 3 oscillators. The power supply for the heater will be taken from the daughter board.

Now I have to ship the first batch items to all the members, on next tuesday.
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Old 5th April 2015, 01:02 PM   #525
TNT is offline TNT  Sweden
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The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator
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Originally Posted by andrea_mori View Post
Now I have to ship the first batch items to all the members, on next tuesday.


BOMs?

//
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Old 5th April 2015, 02:24 PM   #526
justubes is offline justubes  Singapore
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Quote:
Originally Posted by andrea_mori View Post
I have not yet measured the phase noise of the Colpitts-Clapp oscillator. As I said, I have limited access to a university lab, so I will measure all the 3 oscillators (Clapp, Butler and Driscoll) when they will be all ready. For now you can refer to the plot I posted in #5, where the the Clapp oscillator was measured using a similar crystal.

About the SC-cut crystal, I'll not provide any PLL. These crystals could be also used in the Clapp oscillator, while I'll start experimenting soon with Butler 2 emitters and Driscoll oscillators, more suitable for high Q crystals, since the crystal sees a very low impedance, that means very high loaded Q.

Next weeks I'll order the crystal heater PCB (#515). It could be used with all the 3 oscillators. The power supply for the heater will be taken from the daughter board.

Now I have to ship the first batch items to all the members, on next tuesday.
The sc crystal are drop in replacements, am i correct, but can be used to obtain better noise with the clapp oscillator circuit.

Will the connections be simple with the daughterboard. Power and it will output a 3.3v squarewave.

Thanks
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Old 5th April 2015, 02:50 PM   #527
andrea_mori is offline andrea_mori  Italy
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The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator
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Originally Posted by TNT View Post


BOMs?

//
Next week, BOM and assembly guide.
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Old 5th April 2015, 02:58 PM   #528
andrea_mori is offline andrea_mori  Italy
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The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator
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Originally Posted by justubes View Post
The sc crystal are drop in replacements, am i correct, but can be used to obtain better noise with the clapp oscillator circuit.

Will the connections be simple with the daughterboard. Power and it will output a 3.3v squarewave.

Thanks
Yes, you can use SC-cut crystal with the Clapp oscillator to get 3V3 square wave and (theoretically) better phase noise.

Connections with daughter board are the same for power supplies.
Both heaters have to be connected to the DC header of the daughter board with separate wires. The heater board fits the crystal of each XO.
Maybe, the transformer has to be replaced with a 12VA type.
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Old 5th April 2015, 03:51 PM   #529
1audio is offline 1audio  United States
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The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator
Andrea-
I think your first explorations in making an oven will be quite interesting. making an oval copper tube should be pretty easy with a vise. But getting it temperature stable and not melting everything around it is a different issue. The oven will need to operate at over 70C so it will radiate a lot of heat if you don't have good insulation around it and finding the optimum temperature is a unit to unit effort. Typically OXCO's have very carefully designed insulation and heat loss paths. Too much insulation and stability of the oven becomes a problem. The better ovens use a PID controller etc. and double ovens. I don't think that is necessary in this application.

This artiucle will give some broader insight into OXCO's: http://www.vectron.com/products/appnotes/ocxo.pdf
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Old 5th April 2015, 05:59 PM   #530
andrea_mori is offline andrea_mori  Italy
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The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator
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Originally Posted by 1audio View Post
Andrea-
I think your first explorations in making an oven will be quite interesting. making an oval copper tube should be pretty easy with a vise. But getting it temperature stable and not melting everything around it is a different issue. The oven will need to operate at over 70C so it will radiate a lot of heat if you don't have good insulation around it and finding the optimum temperature is a unit to unit effort. Typically OXCO's have very carefully designed insulation and heat loss paths. Too much insulation and stability of the oven becomes a problem. The better ovens use a PID controller etc. and double ovens. I don't think that is necessary in this application.

This artiucle will give some broader insight into OXCO's: http://www.vectron.com/products/appnotes/ocxo.pdf
Demian,
thanks for the link.
Firstly I thought to use epoxy resin to coat the copper tube and the crystal. But in this way the crystal is completely closed and so I have difficult to measure the temp to tuning the heater circuit.
I will leave all open, maybe I could use some thermal paste between the crystal and the tube walls. Operating temperature will be around 80.
As you, I think some temp drift is not an issue for digital audio application.
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