[time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812...

[SAIDJACK at aol.com]

Hi Bob,
 
yes, the 10MHz plot is rotten, no doubt. The 15MHz plot is quite good till  
about 40Hz offset, then it becomes pretty rotten too.
 
Here is one of my 58503A units (using the 10811 OCXO) as a comparison..  
measured against our DROR-IIA (this plot was actually done to show the  
DROR-IIA PN, but since that unit actually has less noise and spurs than the  
58503A we can simply use it as the reference for this purpose).
 
The good news is that getting the close-in phase noise to be good is very  
hard to do and the unit delivers that out-of-the box already. Filtering out 
the  noise and spurs above 40Hz offset is pretty easy to do. It should be 
fairly  straight forward to cobble up a small PN filter for those units to get 
rid of  the noise and spurs above 40Hz offset.
 
bye,
Said
 
 
In a message dated 11/17/2014 09:31:46 Pacific Standard Time, kb8tq at n1k.org 
 writes:

Hi

Here’s the phase noise on the 15 MHz. There are a few  spurs, and an very 
real hump out at the likely frequency of the Lucent  switcher.  The 15 MHz is 
pretty clean compared to most /all of the other  units I’ve seen on the 
surplus market. 

I would not multiply this up to  40 GHz with a broadband multiplier. I 
would be quite happy to run it into a  PLL with a rational bandwidth. You will 
beat the noise on the output with a  fairly simple VHF VCXO past 100 Hz. No 
reason to have a bandwidth outside the  20 to 80 Hz range. 

Math:

15 MHz to 150 MHz -> 20 log (N)  -> 20 db.

-140 dbc / Hz shown below at 100 Hz offset -> -120  dbc/Hz

You can get numbers better than -120 dbc/Hz at 100 Hz offset out  of a 
number of pretty simple VHF VCXO circuits. Bert has one that seems to  work fine 
for him.  

Bob


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