[time-nuts] retry: PRS10 has spurious frequencies

Henk ten Pierick henk at deriesp.demon.nl
Mon Apr 23 13:49:24 EDT 2007


On Apr 22, 2007, at 23:47, SAIDJACK at aol.com wrote:

> Hi Henk,
>
> great to hear that you got a Wavecrest DTS-2075!! That machine can   
> detect
> spurs that phase noise measurements are oblivious too. Spurs cause  
> nasty
> deterministic jitter of course.

That DTS2075 is at my employers lab.

> That must have been the unit for sale on Ebay  for
> $900?

The $900 unit on ebay was a DTS2070.
Yes, I have bought that unit for my home lab but it has not yet arrived.

> Attached is a PRS-10 phase noise plot I measured here with a  
> TSC-5120A  unit.
> You can see pretty low spurs, but only a 100KHz measurement range.  
> One  would
> think to have a perfect oscillator until plugging in the PRS-10  
> into the
> Wavecrest...

Your nice picture shows a -95dBc phase noise at 10Hz.
The SRS spec for PRS10 is -130dBc at 10Hz. Can you explain that  
difference of 35dBc?

Your picture's input level is 5dBm.
The SRS spec for PRS10 is 7dBm output. Were is the difference?

Did you measure wideband spectrum of the PRS10 output? Up to 1GHz?

> BTW: do you have Visi for windows by any chance?

An old evaluation version3

> I have two DTS units, one with about 2.7ps jitter on the  100MHz  
> output
> another with about 3ps. I wonder if replacing the  internal Vectron  
> 100MHz OCXO
> (which really is very low tech - I opened one  and it actually uses  
> a CA3130 as
> the oven controller :( ) would improve the  unit's performance??

Do you have the Vectron OCXO specs?

Henk




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