The Well Tempered Master Clock - Building a low phase noise/jitter crystal oscillator

[clsidxxl]

Hi,

I've sent Andrea the global datasheet for concerned GB members.
Each config is particular, it takes time to check all options.
Work is on the way, waiting for Andrea's answer.
As I've sent it right now, please be patient.
I'm close to send Paypal request before ordering parts.

Regards

Phil

Thank Phil😉

 

[gentlevoice]

Simple, easy & non-expensive phase noise measurement - & feedback.

Hi all,

So now I have assembled the first of my oscillators (24.576 MHz) - based on the current PCBs & oscillator design. I have also had a chance to power it up - and measure a bit. Additionally I've - briefly - taken a look at the links 1audio & Andrea have provided regarding the upcoming Driscoll oscillator topology. Very interesting, indeed ... More on this below ...

Comments/observations on the oscillator
This has all led to some observations that I will briefly share here, and some questions that I hope there's a reply to e.g. from Andrea. The observations first:

1. A good thing is that the oscillator according to my oscilloscope appears to be oscillating at 24.576 MHz (cannot be measured precisely - but it indicates close to this frequency). YES! & a thanks to Andrea I look forward to listening to its qualities on the DACs I use.

2. The output (with a 3.4 VDC LiFePO4 battery powering the inverter) is appr. 1 Vpp measured with a 50 MHz probe (X1 setting). Not ideal measurement tools but just as an indication. The crystal etc. are powered from a 12.6 VDC battery (I also have a question below on this).

3. I've made an ad-hoc HF add-on probe to my oscilloscope (http://www.diyaudio.com/forums/equi...ier-my-oscilloscope-probes-6.html#post4504337) which more or less by choice is not very well shielded. The idea is that besides being able to give an indication of residual PSU HF noise it may also pick up EMR noise from the circuitries. I get an indication of where the HF noise is high, and the noise levels, by moving the probe over the various parts of the circuitry and seeing what goes on on the oscilloscope. I'm aware that this is not a rigorous scientific method, however, it seems to give a quite good indication of what is going on.

And comparing the TWTMC oscillator PCB with a NZ2520SD based layout I've made, the EMR noise levels appear to quite a bit higher from the TWTMC PCB - especially in the center of the PCB around the JFET & the schottky diode are, and the underlying shielding is not present. Identical noise levels are present below the PCB where the shielding is removed (not really surprising). Around the inverter the EMR levels are relatively much lower.

I mention this because I personally will consider shielding the oscillator PCB - and a suggestion could be to maybe include shielding pads/a shielding option in the upcoming PCB layouts?

4. Using the 150k & 220k resistor options for configurable duty cycle I get about 25%/75% duty cycle from visually reading the oscilloscope ... (C6 is 100 nF//680uF; PSU Cap values higher - shouldn't make a difference here...?)

So with these words for now no further comments/observations on the oscillator ...

Questions
However, as I mentioned above some questions have also popped up that I hope maybe Andrea can help answering ... These are:

1. I would prefer using an appr. 12.6 VDC SLA battery for the Vs supply. Do you think this will change the performance of the oscillator in a negative way (worse phase noise specs)?

2. I remember reading somewhere in this forum that there could be a "somewhat" simple way of measuring phase noise that doesn't require expensive equipment (maybe even DIY 🙄). Any of you have any ideas about this? Could be feasible to actually measures what happens with the oscillator ....

3. From #755

If they will not work anyway, I have almost ready the Driscoll emitter coupled oscillator (to be used with SC-Cut crystals), that should be work fine also with harmonic AT-cut crystals.

... If I read this correctly it means that the Driscoll emitter oscillator will not work with the < 45 MHz AT cut crystals ... Is this correct?

4. I probably will be doing my own oscillator PCBs (to adapt the oscillators to my purposes), and to this end I wonder if there are some critical distances or the like to observe between the components? I reckon the unshielded part of the PCB is there to avoid parasitic capacitances on this oscillator signal - but will you say there are any other important aspects to consider in the oscillator part (not inverter part)?

The Driscoll oscillator
And then, finally, a couple of comments to the links/sources regarding the Driscoll oscillator that 1audio & Andrea have previously posted (#767 & #770). I've very briefly read into these and were not least impressed by the performance shown in fig. 5.6 (p.96; attached) in 1audio's first link ... If this is the kind of performance that may be achieved with a Driscoll oscillator that would IMHO be remarkable ...

Cheers & ciao,

Jesper

 

[Alexiss]

I would like to extend my thanks to Andrea for making available a good Xtal and oscillator-board for the fellow diy:ers here.

An important parameter to consider in Xtal based Oscillator design is the associated "Drive Level" and the "Power Dissipation Factor" of the resonator element, (correctly pointed out by 1audio very briefly in the beginning).

Unfortunately there are no remedies for DL control in this design (No, the Gate diode is not the correct solution).
This can, and will lead to serious problems (increased phase noise or "jitter" as a function of time, exaggerated mechanical wear and ultimately damage to the Xtal) just to name a few, in particular for higher f clocks (16.9 MHz and up).

The design is good for preliminary verification of the functionality of the oscillator, not as a final design to be used as master clock - it is incomplete.

I would like to kindly ask Andrea (or 1audio) to consider modifying the current oscillator schematics to address this issue. It would be a shame to degrade the performance of such a nice Xtal.

Cheers.

 

[TNT]

So gentlevoice - you saying that the oscillator is noise limited and that the phase noise in chart can never be practically achieved - would not surprise me.

Alexis - this sounds troubling - we have already got the boards... is this valid only for Driscoll or?

Andrea?

//

 

[clsidxxl]

Thank gentlevoice for the report,finally What have you put for bypass cap.You can try Reflektor D to feed.

 

[gentlevoice]

Hi again,

Just briefly to address what looks like a mis-communication/understanding:

So gentlevoice - you saying that the oscillator is noise limited and that the phase noise in chart can never be practically achieved - would not surprise me.

No, I think we misunderstand eachother here: I'm not saying the oscillator is noise limited in itself - I'm saying that it appears to emit more EMR (electromagnetic radiation) out of the PCB than an NZ2520SD oscillator I've made. I don't know if this noise will disturb the oscillator itself but assuming that it will be close to other noise sensitive audio electronics I'm considering myself to shield it (or make another PCB to suit my particular purposes).

I hope this makes it clearer.

@clsidxxl: Just noticed you had also posted ... You're welcome.

Thank gentlevoice for the report,finally What have you put for bypass cap.You can try Reflektor D to feed.

When asking for bypass cap which cap do you then mean? Thanks also for the suggestion for a PSU solution but I much prefer batteries - either stand-alone or fed from a non-reactive wideband low noise PSU.

Greetings,

Jesper

 

[clsidxxl]

"When asking for bypass cap which cap do you then mean?"
You have open a topic on the bypass cap very interesting,it is not for the XO of Andrea?
Here very interesting products for shield.
EMI RFI shielding gaskets, Faraday cages & powerfilters solutions
Reflektor is a wideband low noise🙂

 

[gentlevoice]

@clsidxxl:

"When asking for bypass cap which cap do you then mean?"
You have open a topic on the bypass cap very interesting,it is not for the XO of Andrea?

I suppose you mean this thread?

http://www.diyaudio.com/forums/digi...hnical-effects-possible-design-solutions.html

It's actually not specifically aimed at the TWTMC XO but digital decoupling in general.

I tried to make some measurements with a couple of likely suitable capacitors (to my memory 100nF; 1 uF & 39nF) and the one that had the simplest PSU noise waveform was the 39 nF. The 39 nF also is the one that has the lowest impedance/ESR around the 24.576 MHz frequency (reference Kemet Spice design tool).

I use a C0G type and combine it with higher value electrolytics to my liking (starting out with a lower value with closely spaced pins to reduce inductance).

From an "optimal" engineering/audibility point of view I would be leaning towards Andrea's choice of a 1 uF (i.e. ~ higher value) capacitor because of its very straight decoupling curve relative to frequency, however, I haven't found any high quality - and still small for low inductance - capacitors. Thus the choice of the C0G type.

Hope this clarifies it.

Cheers,

Jesper

 

[clsidxxl]

Yes this thread.
If you can use LW reverse or three terminal cap.
Some reading.
http://www.murata.com/~/media/webrenewal/support/library/catalog/products/emc/emifil/c39e.ashx

 

[gentlevoice]

@clsidxxl:

Thanks for the link. I've just quickly looked at the document and it looks interesting - but it also is pages so I won't have time to read more into it in the days to come. But when more time - I will ...

Regards,

Jesper

 

[gerhard]

...
2. I remember reading somewhere in this forum that there could be a "somewhat" simple way of measuring phase noise that doesn't require expensive equipment (maybe even DIY 🙄). Any of you have any ideas about this? Could be feasible to actually measures what happens with the oscillator ....
...
3. From #755 ... If I read this correctly it means that the Driscoll emitter oscillator will not work with the < 45 MHz AT cut crystals ... Is this correct?
...
The Driscoll oscillator
And then, finally, a couple of comments to the links/sources regarding the Driscoll oscillator that 1audio & Andrea have previously posted (#767 & #770). I've very briefly read into these and were not least impressed by the performance shown in fig. 5.6 (p.96; attached) in 1audio's first link ... If this is the kind of performance that may be achieved with a Driscoll oscillator that would IMHO be remarkable ...

2. If you already own a 2 channel Fourier analyzer that can do cross corelation, one
probably could work something out, at least for fixed frequencies. It would take 3
similar oscillators to calculate the 3 cornered hat to determine each oscillators
share of the mess. You will have trouble to shield them between each other so
they do not lock to their neighbours altogether. Calibration would be a problem.

3. The Driscoll will work nicely way below 45 MHz. I think the first ones ever were
overtone crystals near 5 MHz long before SC was invented.

The one in the link is hopelessly optimistic. It is much better than the Aeroflex
test gear at any frequency and that probably uses correlation. You won't be able
to buffer that without spoiling everything, let alone convert it to CMOS.

And it has no carrier frequency given. This is like saying "my car needs 1.234
gallons for I-Dont-care miles". A factor of 10 in the carrier frequency equals
20 dB vertically, everything else being equal.

If you really want to feel humiliated, connect your best osc to an Agilent E5052.
I did, more than once.

regards, Gerhard

 

[gentlevoice]

Hi Gerhard,

... thanks for your feedback & comments. To be honest it is somewhat beyond my field of knowledge but reading your point "2" I realize that measuring jitter is not going to be possible with the combination of equipment & know-how that I possess. But fine to have it clarified. Also that I should be able to use the AT cut crystal I now have with the Driscoll oscillator - if feasible.

To that end I also just did a search on the Agilent you mention ... in my perspective not exactly a cheap piece of equipment 🙄

Cheers,

Jesper

 

[andrea_mori]

Hi all,

So now I have assembled the first of my oscillators (24.576 MHz) - based on the current PCBs & oscillator design. I have also had a chance to power it up - and measure a bit. Additionally I've - briefly - taken a look at the links 1audio & Andrea have provided regarding the upcoming Driscoll oscillator topology. Very interesting, indeed ... More on this below ...

Comments/observations on the oscillator
This has all led to some observations that I will briefly share here, and some questions that I hope there's a reply to e.g. from Andrea. The observations first:

1. A good thing is that the oscillator according to my oscilloscope appears to be oscillating at 24.576 MHz (cannot be measured precisely - but it indicates close to this frequency). YES! & a thanks to Andrea I look forward to listening to its qualities on the DACs I use.

2. The output (with a 3.4 VDC LiFePO4 battery powering the inverter) is appr. 1 Vpp measured with a 50 MHz probe (X1 setting). Not ideal measurement tools but just as an indication. The crystal etc. are powered from a 12.6 VDC battery (I also have a question below on this).

3. I've made an ad-hoc HF add-on probe to my oscilloscope (http://www.diyaudio.com/forums/equi...ier-my-oscilloscope-probes-6.html#post4504337) which more or less by choice is not very well shielded. The idea is that besides being able to give an indication of residual PSU HF noise it may also pick up EMR noise from the circuitries. I get an indication of where the HF noise is high, and the noise levels, by moving the probe over the various parts of the circuitry and seeing what goes on on the oscilloscope. I'm aware that this is not a rigorous scientific method, however, it seems to give a quite good indication of what is going on.

And comparing the TWTMC oscillator PCB with a NZ2520SD based layout I've made, the EMR noise levels appear to quite a bit higher from the TWTMC PCB - especially in the center of the PCB around the JFET & the schottky diode are, and the underlying shielding is not present. Identical noise levels are present below the PCB where the shielding is removed (not really surprising). Around the inverter the EMR levels are relatively much lower.

I mention this because I personally will consider shielding the oscillator PCB - and a suggestion could be to maybe include shielding pads/a shielding option in the upcoming PCB layouts?

4. Using the 150k & 220k resistor options for configurable duty cycle I get about 25%/75% duty cycle from visually reading the oscilloscope ... (C6 is 100 nF//680uF; PSU Cap values higher - shouldn't make a difference here...?)

So with these words for now no further comments/observations on the oscillator ...

Questions
However, as I mentioned above some questions have also popped up that I hope maybe Andrea can help answering ... These are:

1. I would prefer using an appr. 12.6 VDC SLA battery for the Vs supply. Do you think this will change the performance of the oscillator in a negative way (worse phase noise specs)?

2. I remember reading somewhere in this forum that there could be a "somewhat" simple way of measuring phase noise that doesn't require expensive equipment (maybe even DIY 🙄). Any of you have any ideas about this? Could be feasible to actually measures what happens with the oscillator ....

3. From #755 ... If I read this correctly it means that the Driscoll emitter oscillator will not work with the < 45 MHz AT cut crystals ... Is this correct?

4. I probably will be doing my own oscillator PCBs (to adapt the oscillators to my purposes), and to this end I wonder if there are some critical distances or the like to observe between the components? I reckon the unshielded part of the PCB is there to avoid parasitic capacitances on this oscillator signal - but will you say there are any other important aspects to consider in the oscillator part (not inverter part)?

The Driscoll oscillator
And then, finally, a couple of comments to the links/sources regarding the Driscoll oscillator that 1audio & Andrea have previously posted (#767 & #770). I've very briefly read into these and were not least impressed by the performance shown in fig. 5.6 (p.96; attached) in 1audio's first link ... If this is the kind of performance that may be achieved with a Driscoll oscillator that would IMHO be remarkable ...

Cheers & ciao,

Jesper

Hi Jesper,
thanks for the feedback.

Where did you measure the output, sine or squared? Keep in mind you are loading the oscillator with the probe, maybe better to set the probe at 10X.

The hole at the bottom side ground plane avoids parasityc capacitance. BTW, you could give a try soldering a little copper sheet to shield that part of the circuit, but I don't believe this will change much. Shielding completely the oscillator should be a good practice, also the moving air can decrease the phase noise performance close to the carrier.

Strange kind you are getting 75%/25% duty cycle with 220K/150K, I remember I tested this values. A simulation shows around 50%/50%. I will give a try again.

You can power the oscillator from 12V to 15V, theoretically you get lower output and always theoretically the phase noise increases just a little. But I don't think that will be a great difference.

About the Driscoll oscillator I'm experimenting, it is optimized for harmonic crystals, so I don't know if it will work with fundamental. BTW, when I'll receive the PCB, I will give it a try. Otherwise, we could shift to harmonic type also for lower frequencies (below 25 MHz), that typically have higher Q. The graph you posted is a bit optimistic, anyway the Driscoll circuit, thanks to the crystal in the emitter circuit, maximizes the loaded Q, that theoretically means decrease the phase noise.

I believe it's not very easy to measure the phase noise with home made gear, the Agilent E5052 is very expensive, around 100000 USD or so. I remember a great article in Wenzel website about building a system to measure the phase noise, but you need anyway a good reference to use with the circuit proposed, at least as good as the oscillator you are measuring.

Andrea

 

[gerhard]

About the Driscoll oscillator I'm experimenting, it is optimized for harmonic crystals, so I don't know if it will work with fundamental.
...
I believe it's not very easy to measure the phase noise with home made gear, the Agilent E5052 is very expensive, around 100000 USD or so. I remember a great article in Wenzel website about building a system to measure the phase noise, but you need anyway a good reference to use with the circuit proposed, at least as good as the oscillator you are measuring.

The Driscoll does not care about overtones or not, just make sure that the collector tank
is at the right frequency. What it wants from the crystal is that its impedance at
resonance is very low compared to the emitter resistor and that the phase slope
of the xtal is steep (another word for Q).

The large emitter resistor reduces the gain for all frequencies not bypassed
by the crystal. That helps push down the noise floor. Remember that when
you simulate the loop gain. It seems much smaller than it actually is at the
oscillation frequency +- some Hz. A sweep from 0 to 200 MHz will probably
not hit these 10 Hz that count.

Every xtal has overtones and you can operate a 10 MHz fundamental one at 30 MHz
for example. It's Q there my be bad, it will be off a few KHz and there may be parasitic
resonances close in. IOW, not optimized for that.

...

You can build Wenzel's thing twice, with 2 reference oscillators. With the DUT you are
at 3 oscillators. You can then measure your DUT with reference 1 and 2 at the
same time and cross-correlate the results. That what is left over is the part from the DUT
that is contained in both results, plus some noise where the 2 references happen
to coincide.

If you average often enough, the part from coincidence goes away. This way, you
can measure up to abt. 20 dB below the noise of the references. Takes some time
for averaging. In principle, that can be done with a stereo sound card.

 

[andrea_mori]

I would like to extend my thanks to Andrea for making available a good Xtal and oscillator-board for the fellow diy:ers here.

An important parameter to consider in Xtal based Oscillator design is the associated "Drive Level" and the "Power Dissipation Factor" of the resonator element, (correctly pointed out by 1audio very briefly in the beginning).

Unfortunately there are no remedies for DL control in this design (No, the Gate diode is not the correct solution).
This can, and will lead to serious problems (increased phase noise or "jitter" as a function of time, exaggerated mechanical wear and ultimately damage to the Xtal) just to name a few, in particular for higher f clocks (16.9 MHz and up).

The design is good for preliminary verification of the functionality of the oscillator, not as a final design to be used as master clock - it is incomplete.

I would like to kindly ask Andrea (or 1audio) to consider modifying the current oscillator schematics to address this issue. It would be a shame to degrade the performance of such a nice Xtal.

Cheers.

Hi Alex,

you are right, the drive level of the Clapp oscillator is strong, but not so high to damage the crystal, at least for frequencies up to 49 MHz, where the crystal ESR is 5 to 13 ohm. The Laptech AT-cut crystals are specified for 500 uW dissipation. There could be a problem wit 90/98 MHz crystal, where the ESR is greater than 30 ohm, but for these frequencies, probably, I will move to Driscoll circuit. Obviously, high drive level influences the aging of the crystal, but in audio devices we don't care about long term stability. Moreover, typically, higher drive level means lower phase noise.
At 11 MHz, considering the crystal ESR around 8 ohm, the RMS current flowing in the crystal should be around 7 mA, and so the dissipation less than 500 uW. At 22 MHz the crystal ESR is around 5 ohm, so the current is around 8 mA and the dissipation around 350 uW. At 45 MHz, where the crystal ESR is around 14 ohm, the current will be less than 7 mA, and the dissipation around 600 uW. At 90 MHz the ESR of the crystal is around 40 ohm, so the RMS current is around 7 mA, and the dissipation around 2 mW, that is a very high drive level.

The Driscoll oscillator drive level will be much lower, since the crystal is located at the lowest power point in the circuit (emitter circuit). The power dissipated in a crystal with ESR around 40 ohm will be less than 300 uW.
Work in progress around the Driscoll oscillator ...

Andrea

 

[andrea_mori]

The Driscoll does not care about overtones or not, just make sure that the collector tank
is at the right frequency. What it wants from the crystal is that its impedance at
resonance is very low compared to the emitter resistor and that the phase slope
of the xtal is steep (another word for Q).

The large emitter resistor reduces the gain for all frequencies not bypassed
by the crystal. That helps push down the noise floor. Remember that when
you simulate the loop gain. It seems much smaller than it actually is at the
oscillation frequency +- some Hz. A sweep from 0 to 200 MHz will probably
not hit these 10 Hz that count.

Every xtal has overtones and you can operate a 10 MHz fundamental one at 30 MHz
for example. It's Q there my be bad, it will be off a few KHz and there may be parasitic
resonances close in. IOW, not optimized for that.

...

You can build Wenzel's thing twice, with 2 reference oscillators. With the DUT you are
at 3 oscillators. You can then measure your DUT with reference 1 and 2 at the
same time and cross-correlate the results. That what is left over is the part from the DUT
that is contained in both results, plus some noise where the 2 references happen
to coincide.

If you average often enough, the part from coincidence goes away. This way, you
can measure up to abt. 20 dB below the noise of the references. Takes some time
for averaging. In principle, that can be done with a stereo sound card.

Gerhard,

thanks for the suggestion about fundamental crystal behaviour in the Driscoll oscillator, I think is not difficult to tune the LC tank in the collector circuit. Anyway, I would prefer 3rd overtone crystals also at lower frequencies, since their Q is higher than the fundamental.

 

[bson]

Is it too late to get onboard for 4x 12.2880MHz and 2x 11.2896MHz, both AT cut?

 

[andrea_mori]

Is it too late to get onboard for 4x 12.2880MHz and 2x 11.2896MHz, both AT cut?

The interest list is still open, for some frequencies the MOQ was not yet met, so you can add yourself to the list and send me the order form.
Members who have not yet sent me the order form, please send me it as soon as possible. Thanks.

 

[bson]

Adding myself to list. Order form sent off.

Interest List SC-cut Crystals from Laptech
- * andrea_mori: 3 x 11.2896 MHz + 2 x 22.5792 MHz + 2 x 24.576 MHz + 1 x 45.1584 Mhz + 1 x 49.152 MHz
- Acko: 1 x 45.1584 MHz + 1 x 49.152MHz
- iancanada: 1 x 22.5792 MHz + 1 x 24.576 MHz + 1 x 45.1584 MHz + 1 x 49.152MHz
- Clsidxxl: 1 x 45.1584 MHz + 1 x 49.152MHz
- lindamar: 1 x 11.2896 MHz 1 x 22.5792 MHz + 1 x 24.576 MHz + 1 x 45.1584 MHz + 1 x 49.152MHz
- * tagheuer: 1 x 45.1584 MHz + 1 x 49.152MHz
- palmito: 1 x 45.1584 MHz + 1 x 49.152MHz
- damohpi: 2x 11.2896 Mhz
- Naimster: 1 x 22.5792 MHz + 1 x 24.576 MHz
- Phi: 1 x 22.5792 MHz + 1 x 24.576 MHz (Added title )
- * ambrosia168: 1 x 22.5792 MHz + 2 x 45.1584 Mhz + 2 x 49.152 MHz
- * flowerpot: 1 x 45.1584 MHz + 1 x 49.152MHz + 2 x PCB + 1 x daughter board + 2 x DIL
- jdlvfr: 3 x 11.2896 Mhz
- wlowes: 1 x 45.1584 MHz + 1 x 49.152MHz
- * fralippo: 1 x 45.1584 MHz + 1 x 49.152MHz + PCBs
- * duster1: 1 x 45.1584 MHz + 1 x 49.152MHz + 1 x 90.3168 MHz + 1 x 98.304MHz + PCBs
- deanoUK: 1 x 45.1584 MHz + 1 x 49.152MHz
- * BDL: 1 x 22.5792 MHz
- * vita : 1 x 45.1584 Mhz + 1 x 49.152 Mhz
- Malvin: 1 x 45.1584 MHz + 1 x 49.152MHz
- rlim: 1 x 22.5792MHz + 1 x 24.576MHz
- Canvas: 1 x 45.1584 Mhz + 1 x 49.152 MHz
- * mcluxun: 1 x 45.1584 Mhz + 1 x 49.152 MHz
- grzegrzol: 2x 11.2896 2 x 22.5792 MHz + 2 x 24.576 MHz + 2 x 45.1584 MHz + 2 x 49.152 MHz
- * jims: 1 x 11.2696 Mhz + 1 x 45.1584 Mhz + 1 x 49.152 MHz
- * MadKid: 1 x 24.576 MHz + 1 x 45.1584 Mhz + 1 x 49.152 Mhz + 1 x 90.3168 MHz + 1 x 98.304MHz + 6 x PCBs (D + OVN + DIL)
- * tbrowne 2 x 22.5792 MHz + 1 x 24.576 MHz + 1 x 45.1584 MHz + 1 x 49.152 MHz + 1 x 90.3168 MHz
- * jborden: 2 x 45.1584 Mhz + 2 x 49.152 Mhz
- * Stijn001: 1 x 45.1584 MHz, + 1 x 49.152MHz

Second batch AT-cut Crystals from Laptech
- * andrea_mori: 2 x 6.1440 MHz + 2 x 12.2880 MHz + 1 x 16.9344 MHz
- Miklos: 1 x 16.9344 MHz
- Marlowe: 3 x 16.9344Mhz + 3 x 25MHz
- carz 1x 27MHz
- 1audio : 1X6.1440MHz
- * mravinsky : 2 x 16.9344Mhz + (2 x TWCMC-C XO board +1 x daughter board) if possible
- * noizas : 2 x 16.9344 MHz
- randytsuch: 2x 25.0000 MHz
- casshan: 1 x 11.2896 MHz + 1 x 12.288 MHz + 2 x PCB + 1 x daughter board
- Fabian85: 1x 16.9344 MHz, 2x PCB + 1x daughter board
- * duster1: 2 x 16.9344 MHz, 1 x 45.1584 MHz, 2 x PCB + 2 x daughter board
- * RollE2k: 1 x 45.1584 MHz + 1 x 49.152MHz + 2x PCB + 2x daughter board
- * shendrik: 2 x 22.5792 MHz + 2 x 24.576 MHz
- grzegrzol : 2 x 16.9344 MHz + 2 x 22.5792 MHz + 2 x 24.574 MHz + 2 x 25 MHz 2 x 45.1584 MHz + 2 x 49.152MHz
- * jborden: 2 x 25.000 Mhz + 2 x PCB
- smanz:1 x 45.1584 MHz, + 1 x 49.152MHz, 1x TWTMC-D&D, + 2x TWTMC-C
- * jims: 1 x 6.1440 Mhz + 2 x 16.9344 MHz + 6x TWTMC-C +3x TWTMC-D&D + 6 x TWTMC-DIL
- * tbrowne 5 x 22.5792 MHz + 3 x 24.576 MHz + 1 x 45.1584 MHz + 1 x 49.152 MHz
- * bson 4x 12.2880MHz + 2x 11.2896MHz + 2x XO_PCB

 

[gentlevoice]

@Andrea:

Thanks for your feedback, Andrea. A few comments to follow up on this:

Where did you measure the output, sine or squared? Keep in mind you are loading the oscillator with the probe, maybe better to set the probe at 10X.

I measured it after the inverter so squared. But I personally would expect that the 1X loading would reduce the output - which is why I mentioned that this was my way of measuring. To my memory it is not much different than what the NZ2520SDs output measured with a 1X probe.

Strange kind you are getting 75%/25% duty cycle with 220K/150K, I remember I tested this values. A simulation shows around 50%/50%. I will give a try again.

... I also will play with the values to see where it goes ...

You can power the oscillator from 12V to 15V, theoretically you get lower output and always theoretically the phase noise increases just a little. But I don't think that will be a great difference.

... Good to hear ;-)

Cheers,

Jesper