[time-nuts] retry: PRS10 has spurious frequencies

[SAIDJACK at aol.com]

In a message dated 4/22/2007 12:55:08 Pacific Daylight Time,  
henk at deriesp.demon.nl writes:

>John,

>The PRS10 has a phase noise spec of -130dBc at  10Hz distance. The  
>only way for me to measure this is with a  Wavecrest 2075 and the  
>PRS10 was not a expected. It was not  better than my R&S SMX. Trying  
>to find out why I found the  spurious which also are seen by the  
>Wavecrest. I will filter the  spurious out of coarse and re-measure  
>but are at least surprised  to find this frequency spectrum.
>I know that there are more PRS10  owners with the time-nuts, I expect  
>them to be phase-noise-nuts  as well.

Henk




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 must have been the unit for sale on Ebay  for 
$900?
 
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...
 
BTW: do you have Visi for windows by any chance?
 
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??
 
thanks,
bye,
Said



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