[time-nuts] retry: PRS10 has spurious frequencies

[SAIDJACK at aol.com]

In a message dated 4/23/2007 10:51:38 Pacific Daylight Time,  
henk at deriesp.demon.nl writes:
 
Hi Henk,


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

Same OCXO as the DTS2075...


>  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?

The X axis is labeled in exponential form by the TSC instrument, it's  
actually -95dBc/Hz at 1Hz (10E0), and -130dBc/Hz at 10Hz (10E1) just  meeting the 
SRS specifications.


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

I think this falls almost within the range of the output of the PRS-10 (6 -  
8dBm range), but I may have used a 1.5dB attenuator for better VSWR (don't  
remember), but for phase noise measurements I don't usually add  attenuation.
 
Also, I think that power number by the TSC-5120A is not very accurate  itself 
(single digit resolution etc).


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

Not yet, but I will try that tonight.


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

An old evaluation  version3

Can I get a copy for evaluation from you please? I bought version 1.16,  very 
old and have been desperately trying to find a more modern version that  runs 
on Win2K etc.


>  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?

No, but someone on this list mentioned some time ago that they sold these  
units to Vectron (Bruce?) and posted some specs, I forgot who that was  
unfortunately...
 
I had a third DTS unit for parts, and that unit's Vectron was out of spec  
(just shy of 100MHz at full mechanical deflection unfortunately). Datecode 1994, 
 so not too bad.
 
Bye,
Said


Henk






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