Clock experiments

[wizard]

50 ohm looks like not so good on digital, I've seen it used by darTzeel so it works very good on analog.



One can use a SMA to 75 ohm BNC adapter - connect it directly to the BVA.

[custodian]

Originally Posted by wizard

50 ohm not so good on digital, I've seen it used by darTzeel so it works very good on analog. One can use a SMA to 75 ohm BNC adapter - connect it directly to the BVA.

What's you evidence for the 50ohm connector being a problem? All the rubidium modules I've looked at use that connector so always used with adaptor. In the audiophile products, the rear panel 75ohm BNC is connected via adaptor to the 50ohm internal rubidium module. I've also seen the 9pin connector on the rubidium clock wired directly to 75 ohm BNC but no great audible difference.

[wizard]

Originally Posted by custodian

What's you evidence for the 50ohm connector being a problem? All the rubidium modules I've looked at use that connector so always used with adaptor. In the audiophile products, the rear panel 75ohm BNC is connected via adaptor to the 50ohm internal rubidium module. I've also seen the 9pin connector on the rubidium clock wired directly to 75 ohm BNC but no great audible difference.

Found it on Wikipedia, no problem up to 10 MHz, only above it.

"At frequencies below 10 MHz the impedance mismatch between a 50 ohm BNC connector or cable and a 75 ohm one has negligible effects. BNC connectors were thus originally made only in 50 ohm versions, for use with any impedance of cable. Above this frequency, however, the mismatch becomes progressively more significant and can lead to signal reflections."

[custodian]

One thing to watch in the 10mHz cable is to avoid external vibrations. Moving the cable will affect the signal. I've seen demonstrations of this at CERN looking in detail at signal effects. More important than worrying about 50ohm connectors is looking at ways to isolate the cable from audio frequency vibrational energy.

[custodian]

I received the following e-mail this morning from Sforzato's distributors:

"Regarding the PMC-00 BVA EX, the Occilloquarza 8607 unit will be end of
life of production.
The last order of the unit is Dec 15 this year.
If you really interested in the PMC-00 BVA EX, please order by the end of October."

Better get your cheque books out, guys!

[Glisse]

As Oscilloquartz use the 8607 module in quite a few of their product line, you would think there may be a replacement?

Then again, maybe not.

From what I gleaned reading annual reports, they had been losing money for the last few years, and there was a sense the SWATCH group had been putting the screws on their R&D budget. Now they have sold them to ADVA, the focus may be more on networking applications. I don't know enough about this industry to understand whether the short-term accuracy of the BVA OCXO is more or less important than the long term accuracy of the other clocking devices they make?

But based on the excellent post you made earlier describing the different clocking technologies, and where you referenced the network industry, it seems the short term accuracy and low phase noise of the BVA is not required for network transmission. Bye Bye BVA ??

BTW, I did read on a strange bulletin board called Time-Nuts, or similar, that Oscilloscope had implied the OEM price of a 8607 was less than USD6,000. This was in response to a query made to them by someone who was considering a previous model BVA that was going on eBay for USD4,500. Oscilloscope said that price was way too high, and only a little under the new price for an 8607.

Of course, putting an OEM part inside a case with power supply, connectors, labour, overheads etc, probably means a $7k cost, a $10k wholesale to distributor, a $15k to retailer, then a $23k retail price, etc. As you and others have surmised.

[custodian]

Yes, agreed.

I've sent a quotation request to Oscilloquartz for 1 off and 10 off 8607 as well as for selected higher spec variants from one of my US companies that is a credible OEM purchaser so I'll let you know what I get back

[justubes]

Is the bva8607 now priced better for a end of production life osc?

Any updates on this?

[TLi]

I have heard it is possible to link the clock with GPS signal using an antenna. Has anyone tried that before? The GPS clock should be top grade.

[justubes]

If using a OSC like the PRS10 or better like the BVA, dont think there are any GPS references that can give you any better accuracy and phase noise than using these units by using an external reference.

There are many cheaper rubidium osc's that may benefit provided they have a input allowing a more accurate reference.