Clock experiments

[custodian]

To help clarify any misunderstanding on this BVA thing I keep banging on about, let me add a bit of background.

"Several resonator configurations are possible, in addition to the classical way of directly attaching leads to the crystal. E.g. the BVA resonator (Boîtier à Vieillissement Amélioré, Enclosure with Improved Aging),developed in 1976; the parts that influence the vibrations are machined from a single crystal (which reduces the mounting stress), and the electrodes are deposited not on the resonator itself but on the inner sides of two condenser discs made of adjacent slices of the quartz from the same bar, forming a three-layer sandwich with no stress between the electrodes and the vibrating element. The gap between the electrodes and the resonator act as two small series capacitors, making the crystal less sensitive to circuit influences.The architecture eliminates the effects of the surface contacts between the electrodes, the constraints in the mounting connections, and the issues related to ion migration from the electrodes into the lattice of the vibrating element.The resulting configuration is rugged, resistant to shock and vibration, resistant to acceleration and ionizing radiation, and has improved aging characteristics. AT cut is usually used, though SC cut variants exist as well. BVA resonators are often used in spacecraft applications."

So in summary, this is an alternative structure for an OCXO oscillator which is designed to improve both performance and reliability but at the cost of much more complex and expensive production.

[Elberoth]

Originally Posted by custodian

The Sforzato unit does not use a rubidium module. Are you getting confused with the Stute!

Pricing for a BVA oscillator module alone is very high. Depends of course on quantity and exact spec but could certainly much higher than the commercial rubidium modules. For real prices, contact Oscilloquartz in Lausanne and get a quote for BVA 8607.

You are correct. What I meant is the BVA 8607, which is not a rubidium oscilator. I think I read somwhere in this thread it costs $12k in OEM.

[custodian]

Originally Posted by Elberoth

You are correct. What I meant is the BVA 8607, which is not a rubidium oscilator. I think I read somwhere in this thread it costs $12k in OEM.

Yes, I've seen similar pricing but with such OEM production, pricing varies quite a lot between customers and volumes. Maybe I should make a price enquiry on Oscilloquartz.

They also get a spread of performance because of the complexity of the manufacturing process. The top of the quality curve are the "08" variant which sell at a large premium. Total production of this variant is around 12 per year.

[custodian]

I found a quotation for a one off 8607 at 34040 SFR!

That really is a scary price but can be bought for much less by OEM customers.

Also found short term stability comparison with $300k hydrogen maser and the 8607 was better.

[Glisse]

I think Oscilloquartz only deal with large OEM, but they do seem to have quite a few resellers. Why don't you ask them which reseller can provide the 8607?

When I was looking at them, I see also that they did develop prototypes of an 8607-C, with a target of -160dBc/1Hz. They seemed to hit -134dB. This was 2007, never went into production.

http://hal.archives-ouvertes.fr/docs...OSA_ifcf07.pdf

[custodian]

Originally Posted by Glisse

I think Oscilloquartz only deal with large OEM, but they do seem to have quite a few resellers. Why don't you ask them which reseller can provide the 8607? When I was looking at them, I see also that they did develop prototypes of an 8607-C, with a target of -160dBc/1Hz. They seemed to hit -134dB. This was 2007, never went into production. http://hal.archives-ouvertes.fr/docs...OSA_ifcf07.pdf

You are correct. That's how I bought mine.

The current higher performance variant is the -08 model which is actually just selected from the top tested samples of the standard product. That performance grading is normal in this industry

[wizard]

8607 BVA have a 50 ohm impedance with SMA connectors on it.
On the Sforzato 01 they have converted them to 50 ohm BNC.

But what about the 25 ohm impedance difference between BVA and 75 ohm BNC connector on dCS Vivaldi Master Clock and CH C1 sync card, can this difference be heard?

I see that dCS Vivaldi Master Clock accepts 1, 5 and 10 MHz on the ref input.
And 8607 BVA 5 MHz version phase noise spec is -125 dB ( Option L -130 dB).

5 MHz sounds better than 10 MHz?

[wizard]

Anyone tried this 50 ohm to 75 ohm impedance transformer from Pasternack?


Pasternack matching pads (aka resistive impedance transformers or minimum loss pads) are passive coaxial components that allow impedance matching between 50 Ohm and 75 Ohm systems without introducing a lot of reflection to the circuit. Matching pads from Pasternack are ideal for applications requiring a connection between a 50 Ohm cable and 75 Ohm system.

[justubes]

Originally Posted by wizard

Anyone tried this 50 ohm to 75 ohm impedance transformer from Pasternack?


Pasternack matching pads (aka resistive impedance transformers or minimum loss pads) are passive coaxial components that allow impedance matching between 50 Ohm and 75 Ohm systems without introducing a lot of reflection to the circuit. Matching pads from Pasternack are ideal for applications requiring a connection between a 50 Ohm cable and 75 Ohm system.

This pads causes loses of a few db,at at 0.5v direct fro the 10m osc output, it can have problems with the signal becoming too low for a good lock. Any one knows?

[custodian]

Originally Posted by wizard

8607 BVA have a 50 ohm impedance with SMA connectors on it. On the Sforzato 01 they have converted them to 50 ohm BNC. But what about the 25 ohm impedance difference between BVA and 75 ohm BNC connector on dCS Vivaldi Master Clock and CH C1 sync card, can this difference be heard? I see that dCS Vivaldi Master Clock accepts 1, 5 and 10 MHz on the ref input. And 8607 BVA 5 MHz version phase noise spec is -125 dB ( Option L -130 dB). 5 MHz sounds better than 10 MHz?

It would be much better if the Vivaldi could accept higher frequency band, say 10-15mHz.