[time-nuts] another Ebay mixup, 5370

SAIDJACK at aol.com SAIDJACK at aol.com
Sun Jun 10 00:43:35 EDT 2007


 
In a message dated 6/9/2007 17:54:34 Pacific Daylight Time,  
bruce.griffiths at xtra.co.nz writes:


>It would be nice to have a look at the jitter spectrum (of  Said's 5370 
>), to see if there are any line frequency related  components.
>After 20 years or less some of the power supply electros  may be suspect.

>Bruce



Hi Bruce,
 
Ok, after fighting my Wavecrest software (yuk, I had to restart my PC  about 
10 times, the NI GPIB stuff is not that great either), I finally measured  the 
5370B output jitter.
 
Attached is the Histogram, it is clear that there is a bi-modal jitter on  
the output that's causing the 223ps RMS jitter. There is a modulation going on  
inside the unit. I think it's the little hump in the middle of the sinewave  
visible in the scope pics I had sent earlier.
 
Also attached is the FFT of the jitter itself (ohhhh, ahhh! the Wavecrest  
software is somewhat useful after all). Here it can be seen that there is  a 
very strong 5MHz component, with a -30dB noise floor.
 
The unit is actually relatively young (1990's), and has virtually no  dust 
whatsoever in it. Seems to have had very low usage. The actual 10MHz is  pretty 
accurate, to within 10mHz.
 
Has anyone else measured the 5370B output jitter?
 
bye,
Said



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