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

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#682
MadKid said:
I'm a bit late aware of this thread.

But Andrea is the AT-cut 90/98 MHz crystals ready for the current Clapp circuit yet?

Will the use of SC-cut crystals lead to a complete redesign of the circuit like mentioned above?

Thanks
Click to expand...

I'm still working on the Clapp oscillator with AT-cut 90/98 MHz crystals. These crystals have higher ESR, around 37 ohm, so seems that the J310 has not enough gain to overcome the losses in the network to get the oscillator starting. I hope to fix this issue soon.

About the SC-cut crystals, as I said previously, probably they won't work in the Clapp circuit, since their ESR is very high (around 110 ohm).
So I have to shift to other oscillator circuit, such as the Butler or the Driscoll type, more suitable for high Q crystals.
I'll start the new design as soon as I get the crystals, if we reach the MOQ requested from the manufacturer.
 
#683
Interest List SC-cut Crystals from Laptech
- andrea_mori: 2 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
- babaudio : 2 x 22.5792 MHz + 2 x 24.576 MHz
- 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: 1x 11.2896 Mhz (or 2x if reqd.)
- Naimster: 1 x 22.5792 MHz + 1 x 24.576 MHz
- noizas: 1 x 11.2896 MHz + 1 x 45.1584 MHz
- Phi: 1 x 22.5792 MHz + 1 x 24.576 MHz (Added title )
- ambrosia168: 3 x 11.2896 MHz + 3 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: 2 x 11.2896 Mhz
- tods: 1 x 22.5792 MHz + 1 x 24.576 MHz + 1 x 45.1584 MHz + 1 x 49.152MHz
- 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 + 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 11.2896 MHz + 1 x 22.5792 MHz + 1 x 24.576 MHz + 1 x 45.1584 Mhz + 1 x 49.152 MHz
- gerhard: 10x 100 MHz


Second batch AT-cut Crystals from Laptech
- 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
- andrea_mori: 2 x 6.1440 MHz + 2 x 12.2880 MHz + 2 x 16.9344 MHz
- Fabian85: 1x 16.9344 MHz, 2x PCB + 1x daughter board
- duster1: 2 x 16.9344 MHz, 2 x PCB + 2 x daughter board
- RollE2k: 1 x 45.1584 MHz + 1 x 49.152MHz + 2x PCB + 2x daughter board
- Stijn001: 1 x 45.1584 MHz, + 1 x 49.152MHz, 1x TWTMC-D&D, + 2x TWTMC-C, + 4x TWTMC-DIL

For my entry, I have removed the odd frequencies since I'm more into metrology and not really audio.
What is the difference between the two 100MHz SCs, other than temperature?
There is no real data sheet anywhere. Given the prices @10, 100MHz looks interesting for
playing around even if one wants 98.x in the long term.

Let me repeat that SC won't work reliably in a circuit that does not have a trap
at the spurious resonance at 10% above the intended frequency. The spurious
resonance may be even stronger than the nominal frequency.
Has anybody measured s-parameters or otherwise modeled the Laptech crystals?
BTW some years ago, I tried to simulate loop gain with LTspice and found the
frequency resolution of LTspice not good enough. (.5 Hz steps @ 100 MHz did
not really work.)

I'll be in Scotland with my motor bike the next 2 weeks, I hope I'll get
internet access.

regards, Gerhard
 
#684
gerhard said:
What is the difference between the two 100MHz SCs, other than temperature?
Click to expand...

Follows the specs of the crystals in stock, there was a quotation mistake from Laptech, they are 10 MHz and not 100 MHz:

XT3871
10M
SC 3RD overtone
HC43
ESR: 90 Ohm max
C0: 2.6PF nominal
C1:0.16FF nominal
Lower temperature turn point: 80C to 90C
Calibration tolerance @ 85C: ±2ppm
Q: 1000K min


XT3939
10M
SC 3RD overtone
HC43
ESR: 95 Ohm max
C0: 2.6PF nominal
C1:0.16FF nominal
Lower temperature turn point: 85C to 97C
Calibration tolerance @ 90C: ±2ppm
Q: 1000K min
 
#685
andrea_mori said:
Follows the specs of the crystals in stock, there was a quotation mistake from Laptech, they are 10 MHz and not 100 MHz:

XT3871
10M
SC 3RD overtone
HC43
ESR: 90 Ohm max
C0: 2.6PF nominal
C1:0.16FF nominal
Lower temperature turn point: 80C to 90C
Calibration tolerance @ 85C: ±2ppm
Q: 1000K min


XT3939
10M
SC 3RD overtone
HC43
ESR: 95 Ohm max
C0: 2.6PF nominal
C1:0.16FF nominal
Lower temperature turn point: 85C to 97C
Calibration tolerance @ 90C: ±2ppm
Q: 1000K min
Click to expand...

I will update soon the order form.
 
#686
Interest List SC-cut Crystals from Laptech
- andrea_mori: 2 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
- babaudio : 2 x 22.5792 MHz + 2 x 24.576 MHz
- 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: 1x 11.2896 Mhz (or 2x if reqd.)
- Naimster: 1 x 22.5792 MHz + 1 x 24.576 MHz
- noizas: 1 x 11.2896 MHz + 1 x 45.1584 MHz
- Phi: 1 x 22.5792 MHz + 1 x 24.576 MHz (Added title )
- ambrosia168: 3 x 11.2896 MHz + 3 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: 2 x 11.2896 Mhz
- tods: 1 x 22.5792 MHz + 1 x 24.576 MHz + 1 x 45.1584 MHz + 1 x 49.152MHz
- 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 + 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 11.2896 MHz + 1 x 22.5792 MHz + 1 x 24.576 MHz + 1 x 45.1584 Mhz + 1 x 49.152 MHz
- gerhard: 10x 100 MHz


Second batch AT-cut Crystals from Laptech
- 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
- andrea_mori: 2 x 6.1440 MHz + 2 x 12.2880 MHz + 2 x 16.9344 MHz
- Fabian85: 1x 16.9344 MHz, 2x PCB + 1x daughter board
- duster1: 2 x 16.9344 MHz, 2 x PCB + 2 x daughter board
- RollE2k: 1 x 45.1584 MHz + 1 x 49.152MHz + 2x PCB + 2x daughter board
- Stijn001: 1 x 45.1584 MHz, + 1 x 49.152MHz, 1x TWTMC-D&D, + 2x TWTMC-C, + 4x TWTMC-DIL
-shendrik: 2 x 22.5792 MHz + 2 x 24.576 MHz
 
#687
Interest List SC-cut Crystals from Laptech
- andrea_mori: 2 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
- babaudio : 2 x 22.5792 MHz + 2 x 24.576 MHz
- 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: 1x 11.2896 Mhz (or 2x if reqd.)
- Naimster: 1 x 22.5792 MHz + 1 x 24.576 MHz
- noizas: 1 x 11.2896 MHz + 1 x 45.1584 MHz
- Phi: 1 x 22.5792 MHz + 1 x 24.576 MHz (Added title )
- ambrosia168: 3 x 11.2896 MHz + 3 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: 2 x 11.2896 Mhz
- tods: 1 x 22.5792 MHz + 1 x 24.576 MHz + 1 x 45.1584 MHz + 1 x 49.152MHz
- 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 + 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 11.2896 MHz + 1 x 22.5792 MHz + 1 x 24.576 MHz + 1 x 45.1584 Mhz + 1 x 49.152 MHz
- gerhard: 10x 100 MHz
- mcluxun: 1 x 45.1584 Mhz + 1 x 49.152 MHz

Second batch AT-cut Crystals from Laptech
- 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
- andrea_mori: 2 x 6.1440 MHz + 2 x 12.2880 MHz + 2 x 16.9344 MHz
- Fabian85: 1x 16.9344 MHz, 2x PCB + 1x daughter board
- duster1: 2 x 16.9344 MHz, 2 x PCB + 2 x daughter board
- RollE2k: 1 x 45.1584 MHz + 1 x 49.152MHz + 2x PCB + 2x daughter board
- Stijn001: 1 x 45.1584 MHz, + 1 x 49.152MHz, 1x TWTMC-D&D, + 2x TWTMC-C, + 4x TWTMC-DIL
-shendrik: 2 x 22.5792 MHz + 2 x 24.576 MHz
 
#688
Updated Order Form

SC-cut crystal
11.2896 MHz 3rd overtone MOQ 15 pcs Eur 38.00 each
22.5792 MHz 3rd overtone MOQ 10 pcs Eur 38.00 each
24.5760 MHz 3rd overtone MOQ 10 pcs Eur 38.00 each
45.1584 MHz 5th overtone MOQ 10 pcs Eur 38.00 each
49.1520 MHz 5th overtone MOQ 10 pcs Eur 38.00 each
90.3168 MHz 5th overtone MOQ 15 pcs Eur 56.00 each
98.3040 MHz 5th overtone MOQ 15 pcs Eur 56.00 each
10 MHz (XT3939) 5th overtone MOQ 1 pcs Eur 98.00 each
10 MHz (XT3939) 5th overtone MOQ 5 pcs Eur 42.00 each
10 MHz (XT3939) 5th overtone MOQ 10 pcs Eur 35.00 each

AT-cut crystal
5.6448 MHz fundamental MOQ 15 pcs Eur 29.00 each
6.1440 MHz fundamental MOQ 15 pcs Eur 29.00 each
11.2896 MHz fundamental MOQ 10 pcs Eur 27.00 each
12.2880 MHz fundamental MOQ 10 pcs Eur 27.00 each
16.9344 MHz fundamental MOQ 10 pcs Eur 27.00 each
22.5792 MHz fundamental MOQ 10 pcs Eur 27.00 each
24.5760 MHz fundamental MOQ 10 pcs Eur 27.00 each
25.0000 MHz fundamental MOQ 10 pcs Eur 27.00 each
45.1584 MHz 3rd overtone MOQ 10 pcs Eur 27.00 each
49.1520 MHz 3rd overtone MOQ 10 pcs Eur 27.00 each
90.3168 MHz 5th overtone MOQ 15 pcs Eur 29.00 each
98.3040 MHz 5th overtone MOQ 15 pcs Eur 29.00 each
 

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#689
gerhard said:
Interest List SC-cut Crystals from Laptech

Let me repeat that SC won't work reliably in a circuit that does not have a trap
at the spurious resonance at 10% above the intended frequency. The spurious
resonance may be even stronger than the nominal frequency.
Has anybody measured s-parameters or otherwise modeled the Laptech crystals?
BTW some years ago, I tried to simulate loop gain with LTspice and found the
frequency resolution of LTspice not good enough. (.5 Hz steps @ 100 MHz did
not really work.)
Click to expand...
Besides Gerhard's warning about the difficulty to suppress the so-called "B"-mode, which is just 9% to 10% above the desired "C"-mode, there my be an issue if you operate an SC crystal without oven at room temperature. Because the frequency vs. temperature characteristic has a rather deep slope around RT, any minor temperature fluctuation will immediately translate into close-to-carrier phase noise and jitter. Thus the inherent advantage of an SC cut may be cancelled by this effect.

Regards
Bernd
 
#692
xtals4u said:
Besides Gerhard's warning about the difficulty to suppress the so-called "B"-mode, which is just 9% to 10% above the desired "C"-mode, there my be an issue if you operate an SC crystal without oven at room temperature. Because the frequency vs. temperature characteristic has a rather deep slope around RT, any minor temperature fluctuation will immediately translate into close-to-carrier phase noise and jitter. Thus the inherent advantage of an SC cut may be cancelled by this effect.

Regards
Bernd
Click to expand...

You are right, indeed I'm also working around a oven for the SC-cut crystals, as you can see in post #515.
I'm waiting for a quote to manufacture a suitable copper adapter for the crystal, made by a milling machine. I have tried to manufacture by myself this item, but the result was not as I expected (#665).

Andrea
 
#697
Hi, Andrea, please remove my entry from the interest list. if it is really 10 MHz
it does not make sense. There are so many perfectly working 10 MHz ovens
out in the wild that it doesn't make sense.

I don't dare to edit a major list on the cell phone.

Greetings from Orkney island, Scotland on a rainy day that is no fun to motorbike.

Gerhard
 
Last edited:
#700
gerhard said:
Hi, Andrea, please remove my entry from the interest list. if it is really 10 MHz
it does not make sense. There are so many perfectly working 10 MHz ovens
out in the wild that it doesn't make sense.

I don't dare to edit a major list on the cell phone.

Greetings from Orkney island, Scotland on a rainy day that is no fun to motorbike.

Gerhard
Click to expand...

You are absolutely right. An HP 10811 can be had for around $100 with performance that can't be duplicated by the DIYer. I did ask the designer (Rick Karlquest) about changing the crystal to a different frequency and he said it would not be successful. Too many details to tweak if I could get a crystal in the special package they used.

There is a lot to learn from the manual: https://www.febo.com/pages/hp10811/HP10811AB-Manual.pdf . It uses an SC cut crystal (I believe HP "discovered" the cut) and you can see all the details necessary to get performance in the link.
 
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