Master Clock for your EtherREGEN

[LewinskiH01]

@DarqueKnight

My BG7BTL from RadioHam arrived too. I had a similar experience to your. 

 

The inside looks the same:

 

And so does the front. I've ask the seller how to know if the outputs are sine or square. Mine looks like your RadioHam unit with three 75 ohm outputs, but also no reference for sine/square.

 

How do you know which is which?

[DarqueKnight]

6 minutes ago, LewinskiH01 said:

@DarqueKnight

My BG7BTL from RadioHam arrived too. I had a similar experience to your. 

 

How do you know which [output] is which?

 

The Ham Radio Shop BG7TBLs are advertised as

"75ohm output by BG7TBL 10MHz OCXO FREQUENCY STANDARD 3 channel square wave clock Master Clock for your EtherREGEN"

 

Therefore all three of the outputs should be square wave. The only way to know for sure is to attach the outputs to an oscilloscope (which is what I did).

 

The BG7TBL I purchased drom TZT shop had, per my request, going from left to right:

 

Output 1 - 75 Ohm Square

Output 2 - 75 Ohm Sine

Outout 3 - 50 Ohm Sine

[Rasputin]

10 hours ago, Clockmeister said:

Hello PYP

 

I also have a Cybershaft 21A (with a significantly improved power supply and internal upgradess I use in one of the smaller demo systems), I have found that cable selections with the vast majority of these clocks can deliver quite surprising results from both very  beneficial to piss poor.

 

For some time I used a genuine RF reference cable (18Ghz BW) using T-Flex 405 very good indeed besting many multi $K audiophile cables.Cost is around $200 dollars for 3 feet un-termiated . Happily use them in my lab for sub 6G work. For audio now I use a different cable, it doesn't quite match that cable for insertion loss or overshot, however it sounds superior without question. The downside is cost. However for you guys try something similar you maybe surprised.

 

My other issue is I require 68 clock cables for the studio/lab and music systems so I have tried one or two different cables over the years

 

 

I have found a huge difference among the bnc cables when used between DCS Rossini DAC and DCS clock, so the notion of a cable “cease  to matter” with a use of a filter goes against my  hearing experience, however I will try as advised in the John’s paper. But would you share which cable you have found to sound best for your studio? 

[R1200CL]

Maybe it’s possible to build your own OCXO. 
https://eprints.whiterose.ac.uk/141563/1/08540461.pdf

VII. CONCLUSIONS
It is shown that oscillators with the excellent phase noise performance can be built using relatively simple but highly accurate linear theories and these can be implemented using a modular approach to oscillator designs, utilizing transformer coupled differential amplifiers, a three-element filter, and high-pass phase shifter designs.
Further improvements in the longer term phase noise per- formance are expected through the improved and optimized temperature stabilization of the resonator at turnover temper- ature (82 °C). Certain types of components have been found to be more effective in keeping the phase noise low.

[Clockmeister]

3 hours ago, Rasputin said:

I have found a huge difference among the bnc cables when used between DCS Rossini DAC and DCS clock, so the notion of a cable “cease  to matter” with a use of a filter goes against my  hearing experience, however I will try as advised in the John’s paper. But would you share which cable you have found to sound best for your studio? 

Hello Rasputin

 

We have a great many clients with DCS Vivaldi stacks as we affectionate call them and all of our customers use an aftermarket reference clock to 'time' the DCS Vivaldi clock.

 

A fair few use Transparent Opus BNC cables, others swear buy Crystal Cables  Absolute dream 75 Ohm bnc cables.

While other use an self constructed RG45 derivative.

 

 

[DarqueKnight]

I placed an order by phone for the Mini-Circuits BLP-10.7+ 50 Ohm and BLP-10.7-75+ 75 Ohm filters.

 

 

 

[R1200CL]

This is a “native” square wave clock. 
How come the data sheet can list phase noise, when phase noise is only available on sine ?

 

http://www.analysir.com/downloads/isotemp ocxo 131 10MHz.pdf

 

 

[Rasputin]

3 hours ago, DarqueKnight said:

I placed an order by phone for the Mini-Circuits BLP-10.7+ 50 Ohm and BLP-10.7-75+ 75 Ohm filters.

 

 

 

I’m very interested in your experience with the filters when you get them, hope you will share.

[Tokyokyoto]

I inquired Paul Pang Audio for clock specs.  What do y’all thinkk?

[R1200CL]

5 minutes ago, Tokyokyoto said:

I inquired Paul Pang Audio for clock specs.  What do y’all thinkk?

I think he didn’t give you 1Hz. 
I think anything below 10Hz -130dBc/Hz may not worth the effort. 

[R1200CL]

Here is the tungsten on place on the BG7TBL
Very simple heat isolation. A 6mm plate used for isolation of heated floors. Double on top.

The heat may loosen the tape, I could probably done better to ensure that. 

 

[Superdad]

16 hours ago, Rasputin said:

I have found a huge difference among the bnc cables when used between DCS Rossini DAC and DCS clock, so the notion of a cable “cease  to matter” with a use of a filter goes against my  hearing experience, however I will try as advised in the John’s paper. 

 

That's because:

a) the dCS clock is a square wave--and cable will always matter for that;

b) what we said about cable not mattering much is only for sine wave and only for if you use a good low-pass filter at the target device input.

 

The above are not minor details. They are the essence of what we put forth. Would really hate to think that folks are going around thinking that John Swenson said clock cable don't matter at all. It is all there in the paper...

 

Cheers,

--Alex C.

 

[PYP]

for those who like their waves square, how do these specs look?  Just curious since I like my waves sine.  

 

Impedance	75+/-3 Ohm
Capacitance	52+/-3 pF/M
Attenuation 20 degree C	5MHz 0.80 dB/100m 10MHz 1.20dB/100m  50MHz 3.20 dB/100m  100MHz 5.40 dB/100m  200MHz 6.50 dB/100m 300MHz 8.50 dB/100m 470MHz 11.00dB/100m  600MHz 13.50 dB/100m  1000MHz 16.40 dB/100m

[DarqueKnight]

2 hours ago, Rasputin said:

I’m very interested in your experience with the filters when you get them, hope you will share.

Of course I will.

[R1200CL]

@PYP

That’s not phase noise numbers ?

Are you trying to find good cables for a square clock ?

[PYP]

8 minutes ago, R1200CL said:

@PYP

That’s not phase noise numbers ?

Are you trying to find good cables for a square clock ?

I was unclear:  the table contains specs for a digital cable.  Personally, since my clock outputs a sine wave, I'm not interested, but thought others who use square wave output might be.  This is  a Townshend Audio cable.  

[jamesg11]

2 hours ago, R1200CL said:

I think he didn’t give you 1Hz. 
I think anything below 10Hz -130dBc/Hz may not worth the effort. 

Cost of Pang starts at?

 

Thinking I’ll stay safe, as per JS paper, & go with an ADark Giesemann sine + filter;

& stay frugal, well relatively, as befits the original purchase ... maybe the King, which specs above 130.

 

It doesn’t matter, but they have a 75ohm option?

[JohnSwenson]

4 hours ago, R1200CL said:

This is a “native” square wave clock. 
How come the data sheet can list phase noise, when phase noise is only available on sine ?

 

http://www.analysir.com/downloads/isotemp ocxo 131 10MHz.pdf

 

 

Phase noise is a property of any periodic signal, sine or square or in between. There seems to be some misunderstanding of what phase noise is.

 

Here is a nice easy to understand article on it. (note in this article it specifically covers phase noise of square waves):

 

https://blog.bliley.com/ultimate-guide-to-phase-noise

 

John S.

[JohnSwenson]

3 hours ago, R1200CL said:

Here is the tungsten on place on the BG7TBL
Very simple heat isolation. A 6mm plate used for isolation of heated floors. Double on top.

The heat may loosen the tape, I could probably done better to ensure that. 

 

I didn't put it in the clock paper but adding thermal insulation to an OCXO will probably make things worse. What you want is "thermal mass" NOT thermal insulation.

 

An OCXO contains a crystal and circuitry in an oven to raise the temperature to the point in the crystal's curve where the temperature changes make a very small change in frequency. There is a sensor (or sensors) that measure the temperature inside and adjust the current flowing through resistances to heat the oven. This means there is "active" heating, the control circuit can control how fast the oven heats up, BUT there is no active cooling. The only cooling is the heat that goes out through the case into the surrounding air.

 

Almost all OCXOs are designed with a fairly small amount of thermal insulation on purpose, this allows them to cool off fairly quickly, which gives them a fairly fast response time. If there is a lot of thermal insulation, if the temperature ever goes a little above the set point it might take an hour for it to cool back down to where it should be. With a small amount of thermal insulation the active heating can keep the insides at the right temperature with a quick response time to both heating and cooling. It is MUCH easier for a control loop to keep the right temperature.

 

Think about steering a car where turning the wheel to the right responded normally, but turning the wheel left took 10 minutes to respond, it would be rather difficult to control. This is what happens to an OCXO when you put a bunch of thermal insulation on it. The control loop can wind up going out of control and the temperature starts wildly fluctuating inside, probably not what you wanted to achieve.

 

The real reason is why you would want to do this in the first place. The temperature stability over which good OCXOs operate has essentially zero to do with phase noise. Trying to make the temperature inside the oven more consistent will NOT improve the phase noise, so don't even try.

 

The two things that will probably have the biggest impact on phase noise that you can control are power supply and vibrations. On the vibration front what seems to be the biggest impact are very low frequency vibrations, so called "seismic noise". Primarily because the crystal mountings for the crystals used in very good OCXOs already do a pretty good job of attenuating higher frequency  vibrations. I have no idea how good the cheaper ones are though. So what is left is the very low frequency noise. Of course these are very hard to attenuate.

 

As an aside on the thermal aspects of OCXOs, many of them don't have any specific "insulation" at all, they just have a bright shiny metal can, this IS their thermal insulation. For a component inside a box most of the cooling occurs through IR radiation to the inside of the case, the bright metal has very poor IR emission, so this cuts down on the heat flow through the case just enough for the heater to keep the internal temperature where it needs to be and still has enough cooling to keep the control loop happy.

 

John S.

 

 

[Clockmeister]

As always interesting thoughts on this subject, we are fortunate our test equipment aelection includes one if these devices  which is awfully useful in this area of high frequency phase measurements

 

https://www.holzworth.com/products/phase-noise-analyzers/ha7062c

 

 

Genuine REAL world ultra low noise phase clocks that are really -120 @ 1Hz and have long term stability and those that do will have an oven or the very top oscillators will have a double oven possibly 

 

Keep up the debate chaps great stuff.

[Superdad]

20 hours ago, Clockmeister said:

Genuine REAL world ultra low noise phase clocks that are really -120 @ 1Hz and have long term stability and those that do will have an oven or the very top oscillators will have a double oven possibly.

 

Aren't those double-ovens more for long term frequency stability and not so much for the benefit of phase-noise?

 

By the way, while that Holzworth looks like a nice machine (about $40K), it seems the less than half the price Jackson Labs PhaseStation (by John Miles of TimePod fame) which John bought last year has a much lower phase-noise measurement floor at low offsets 1Hz~10Hz):

 

http://www.jackson-labs.com/assets/uploads/main/53100A_introduction_1pg_revF.pdf 

https://www.holzworth.com/Portals/0/HA7062C_Web_Datasheet.pdf

 

Good chance your machine runs the cross-correlations faster though. 

 

Cheers to you David,

--Alex C.

[Clockmeister]

ello Alex

 

We use the ha706c specifically for RF applications as the bw starts precisely at the limit of the main word clock reference signals 10Mhz . We have many projects which are in the daylight zone hence why thr Holtzworth is most suitable testbpiece 

 

For the dc to to 10 Mhz I use a 12Ghz RTA with dedicated phase noise app slaved by a mutec se 120 it has 1Hz RBW capability

 

Although not as accurate as the 53100a it is more than capable of differentiating various clock abilities and claims

 

As I mentioned earlier ovens are for oscillator  stability however as they say here 'evey little helps'

 

John mentioned vibration control and power supply  cleanliness and stability are also critical to obtaining a quality result.

 

If we look at the various causes of phase discrimination from the carrier:

 

Semiconductor induced noise on and around the clock circuitry

Power supply induced phase variants 

PLL sources 

Frequenct tuning aspects both with transmission lines and the devices themselves

Any amplifier sections within said design including white noise

There are many other inducements such as Thermal, Johnson and shot noise

 

Its good fun investigating these grey areas for audio alway seems to throw the odd curve ball from time to time!

 

 

 

 

[Tokyokyoto]

2 hours ago, jamesg11 said:

Cost of Pang starts at?

 

Thinking I’ll stay safe, as per JS paper, & go with an ADark Giesemann sine + filter;

& stay frugal, well relatively, as befits the original purchase ... maybe the King, which specs above 130.

 

It doesn’t matter, but they have a 75ohm option?

$895.00 US

[R1200CL]

 @AfterDark.

Isn’t you doing some heat isolation on your clocks ?

Like to explain ? Anyone looking inside your clock should be available to see this.

 

 

• OCXO is enclosed and covered with Dynamat Extreme Corporation (Made in USA) which is used to stabilize and minimize heat separation,  addition EMI material from KEMET EMI Shielding is placed on top of OCXO,  the outer layer is covered with real leather to isolate the heat factors for maximizing OCXO performance . 

[DarqueKnight]

I have received my Mini-Circuits filters. The people at Mini-Circuits were a pleasure to deal with. The order was placed mid-morning and it was shipped early afternoon the same day. It arrived three days later by FedEx.

 

Figure 1. The filters arrived in a sturdy box with copious amounts of protective paper padding.

 

Figure 2. Two of the BLP-10.7-75+ 75 ohm filters and one of the BLP-10.7+ 50 ohm filters were ordered. I have one BG7TBL with three 75 ohm square wave outputs and another BG7TBL with a 75 ohm square wave output, a 75 ohm sine wave output, and a 50 ohm sine wave output.

 

Figure 3. I did not pay attention to the filter size on the spec sheet. I expected them to be smaller.

 

Figure 4. I also received this accessory for my Tektronix TDS 2012 oscilloscope. It is a 75 ohm feed through termination for impedance matching of 75 ohm cables to the scope's 1 M-ohm input impedance.

 

Figure 5. Three 75 ohm BNC cables. Bottom to top: Prosig PSG00542 RG-59/U coaxial cable, 2 meter length. This cable came with my dCS Puccini U-Clock word clock, cost $5, Revelation Audio Labs Prophecy Cryo-Silver with Oyaide BNC connectors, 1.5 meter length, made in 2009, cost $349, Revelation Audio Labs Prophecy Cryo-Silver with Furutech BNC connectors, 1 meter length, made in 2015, cost $449.

 

Figures 6 through 8 show the waveform and amplitude distortions that occurred due to the impedance mismatch between the cables and the scope. The BG7TBL had been on for over 24 hours prior to taking measurements.

 

Figure 6. Square wave pulse train waveform with Prosig cable, impedance mismatch.

 

Figure 7. Square wave pulse train waveform with RAL 2009 cable, impedance mismatch.

 

Figure 8. Square wave pulse train waveform with RAL 2015 cable, impedance mismatch.

 

Figure 9. Square wave pulse train waveform with Prosig cable, impedance matched.

 

Figure 10. Square wave pulse train waveform with RAL 2009 cable, impedance matched.

 

Figure 11. Square wave pulse train waveform with RAL 2015 cable, impedance matched.

 

Figure 12. Square wave pulse waveform with Prosig cable.

 

Figure 13. Square wave pulse waveform with RAL 2009 cable.

 

Figure 14. Square wave pulse waveform with RAL 2015 cable.

 

The RAL 2015 was the best sounding of the BNC cables.

 

Figure 15. Unfiltered sine wave from 75 ohm BG7TBL output.

 

Figure 16. Sine wave from 75 ohm BG7TBL output with 75 ohm Mini-circuits filter.

 

Listening Evaluations

 

Figure 17. EtherREGEN with Mini-Circuits 75 ohm filter at its clock input. Both the EtherREGEN and the BG7TBL clock were powered with separate TeraDak DC-30 linear power supplies.

 

I cannot speak for anyone else's EtherREGEN, but mine, and my ears, much preferred the BG7TBL's square wave input. Switching to the BG7TBL's 75 ohm sine wave input caused a loss of bass detail, diminished tactile sensation, and diminished imaging properties. Inserting the filter caused a further reduction in sound quality, particularly in bass detail.

 

While my results with the Mini-Circuits filter were not positive, I would not discourage anyone from trying it, especially if you have a high quality sine wave clock. Results will vary based on your clock and cables.