Master Clock for your EtherREGEN

[Mihaylov]

On 5/31/2020 at 3:41 AM, Superdad said:

The CCHD-575 is one of the lowest phase-noise production XO available (about $10 each at 500 piece qty,), and our 3 original 25MHz (random production) samples came with plots showing 10Hz-offset phase-noise of -108, -110, and -112 dBc/Hz.

The manufacture specifies larger phase noise values for this oscillator.

 

[Mihaylov]

Fresh product from BG7TBL. And again the new OCXO. Does anyone have specifications of this oscillator?

 

 

 

 

 

[Mihaylov]

ER is still in transit. 

[Mihaylov]

The ER uses clock generator Si5340. Here is its typical jitter from datasheet (circled in yellow):

 

 

Here is jitter of DAPU O55A calculated from its phase noise:

 

 

Do you need a clock with the best features for ER if the limit link still turns out to be Si5340? 

Here is jitter of Cybershaft:

 

[Mihaylov]

1 hour ago, audiojerry said:

But I have not seen any recommendation or concurrence for a reasonbly price sinewave clock. 

The first half of the topic is about such clocks from BG7TBL.

[Mihaylov]

4 hours ago, LewinskiH01 said:

Hello.

 

Today I tried to use my LPS-1.2 to power the BG7BTL and had an error. I believe others have used this combination without problem so I'm wondering what might be wrong?

 

The LPS-1.2 is set to 12V, powered by the supplied Uptone SMPS, connected to the BG7BTL thru a Ghent DC cable. Upon turning on the LPS the led goes from red to orange and when it wants to turn green the power and alarm leds on the BG7BTL blink briefly and go off and the led on LPS blinks red, and this cycle continues for as long as keep the LPS on. The BG7BTL output wasn't connected, if that makes a difference. 

 

Why might this be happening? 

Hi! 

Please tell you what OCXO is installed in your clock?

The fact is that the previous clock had DAPU installed first, then FE180, then Symmetricom. In all cases, their maximum consumption current did not exceed 0.5 A at 12 V (according to datasheet, Symmetricom 159-00057-00 is not known, but rather the same because it's a analog of morion MV200).

[Mihaylov]

 

 

 

 

Only the very first OCXO, which was installed in clock over a year ago, has a maximum consumption current of 0.67 A. But it's unlikely to be installed in your clock.

 

 

 

 

 

 

[Mihaylov]

2 hours ago, LewinskiH01 said:

It's interesting others with BG7BTL with Symmetricom ocxo and LPS-1.2 didn't have this issue.

LPS-1.2 1.1A is more than enough to power Symmertricom with their 12V and 0.55A. Perhaps this is about the LPS-1.2 microprocessor working properly?

 

Symmetricom

Quote

All parameters are the same as MV200.

http://www.morion.com.ru/catalog_pdf/MV200-OCXO.pdf

Volume 50*50*12mm

12V power supply, with voltage control pin, reference voltage output 5V.

This crystal oscillator is made by Morion for Symmetricom, and the main body is MV200 produced by Morion.

This crystal oscillator has the advantages of low phase noise and good stability. It's a very rare piece of material.

Correct link to parameters of MV200.

[Mihaylov]

3 hours ago, richard_crl032 said:

the 50ohm and 75ohm mismatch

Specialists at Cybershaft don't see this as a big problem.

 

 

[Mihaylov]

3 hours ago, aubreybobb said:

clocking from the same unit 

breaks not only the moat in the ER, but also makes it pointless to use the ethernet interface at all (twisted pair or optics all the same) since it deprives ethernet of its main advantage, namely galvanic device isolation. Be very careful in the network configuration so as not to break the galvanic isolation and use a separate clock for each device on the local network, then it will be sufficient one switch instead of several.

[Mihaylov]

Curious how they achieve galvanically isolation of the outputs? With some chips like Alex and John in ER?

 

 

Has anyone tried checking the resistance between the grounds of these outputs? Is that resistance equal to 0 or is there a gap (very large resistance)?

 

 

[Mihaylov]

54 minutes ago, JohnSwenson said:

Most clock boxes that say they are galvanically isolated do so with transformers on the output.

Can't find these transformers on the Mutec board.

 

[Mihaylov]

10 hours ago, aubreybobb said:

after reading a few of the above messages regarding breaking the moat, I decided to remove the clock connection (double emperor dCS version - 2 x word clock and 4 x 10M out) from one ER.  The drop in SQ was dismaying. 

Should have disconnected the clock from Sotm because it stands on a "muddy" bank to the ER.

[Mihaylov]

All network devices before the ER moat must not share electrical ground with the network devices after the ER moat otherwise the moat will be destroyed with all the resulting consequences for sound. The clock outputs share a common electric ground, so simultaneously connecting one output of the clock to the Sotm and the second to the ER connects the electric grounds of the Sotm and ER ("clean" side, because the clock plugs to the ER on the "clean" side after the moat).

[Mihaylov]

On 6/11/2020 at 10:27 AM, JohnSwenson said:

There ARE some ways to convert sinewaves into square waves, but the simple ways actually increase the noise on the signal making the jitter even worse.

 

Is this way simple?

 

Quote

Clipped Sine Wave - the sine wave output is manipulated so it will not reach its max high or low. By doing this you are creating a square wave output without sacrificing any of the desired phase noise performance.

 

[Mihaylov]

14 hours ago, Rasputin said:

Or the network devices can be powered from the same power distributor sharing the ground? 

Yes, they can. It's not so much about grounding the power grid as it is about the electrical ground (common bus) circuitry of devices on the network, including their power supplies. (I hope it's spelled correctly in English).

[Mihaylov]

4 hours ago, R1200CL said:

and the phase noise numbers. 

It is unlikely that Abbas knows what phase noise is, the more it is unlikely to measure it (special rather expensive equipment is required) 😉.

And this is not OCXO, this is pure resonator not oscillator .

 

[Mihaylov]

Hi Alex and John! What output should an external clock have: HCMOS? Or is LVCMOS enough?

[Mihaylov]

42 minutes ago, JohnSwenson said:

Just be careful that the driver can handle a 75 ohm load.

I use the Morion MV197 output directly through the capacitor to connect to the input of an external clock of ER 50 ohm. (I gave a photo a little earlier in this thread). Everything works great. Does this mean that the driver of this oscillator can handle such a small 50 ohm load?

 

[Mihaylov]

On 5/4/2022 at 8:55 PM, Superdad said:

 

Probably still about the same. Various surplus OXCOs used. Get the simplest one--with the least amount of extraneous circuitry--and use the sine wave output from it (their square wave stinks). This one:

https://www.aliexpress.com/item/4000152539910.html?spm=a2g0o.productlist.0.0.59125666SoGnQe&algo_pvid=ea7571cb-94de-4925-9ce6-2e0e800acf7d&algo_exp_id=ea7571cb-94de-4925-9ce6-2e0e800acf7d-20&pdp_ext_f={"sku_id"%3A"10000000471375324"}&pdp_npi=1%40dis|USD||87.4|||||%402101fd4b16516867010227325e197c|10000000471375324|sea

Alex, this isn't a good choice. The fact is that on all such boards, the sin wave signal from the oscillator output is first converted into a square wave signal in the simplest way, which is fed directly to the square output of the clock, and to sin output through the simplest CLC low pass filter.

 

 

It's better to use one. There is a sin wave output directly from the pin of the oscillator.

 

[Mihaylov]

You can also choose models with oscillators with improved phase noise values. But I don't know how much I can trust.

And a very good cable for this boards.

[Mihaylov]

21 minutes ago, Superdad said:

I don't disagree with you at all on this. The BG7TBL is an overly complex, poor execution design.  (Though in the end the square wave output of their units is still worse than their sine>square>sine path.) Simpler is better in this case!  

Sorry Alex, I don't understand you. I have given alternative models that represent the direct output of the signal from the output of the oscillator. These models have nothing to do with the BG7TBL.

This is how they look from the back side - it couldn't be easier! :D 

[Mihaylov]

8 minutes ago, R1200CL said:

……so one could even gamble on purchase a clock equal to AfterDark for well below

$200, and test 😀

Don't do it. It is better to choose the standard cheapest model with Symmetricom. Even such a model should make it possible to hear the advantages of the external clock over the built-in ER (as practice shows).

ps It's for @rah50.

[Mihaylov]

16 minutes ago, R1200CL said:

Better add some $$$$, and purchase from AD

Sorry, but I don't know the origin of the oscillators that AD uses in its products. Luckily I am able to order the best new oscillators from Morion at an affordable price. 😀

[Mihaylov]

1 hour ago, FIndingit said:

Is that ceramic cap c1 really necessary at the clock output? Could it be detrimental? 

There is no harm from this ceramic capacitor (especially for a sinusoidal output signal).
This capacitor provides a galvanic isolation of the output of the oscillator and the input of the receiver for the external clock (it may generally be necessary).