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

[Mark Spencer]

One of my Z3805's (with the double oven 10811 ocxo iirc) also performs similarly at times to the 58503A mentioned by Said.   From an adev perspective it's close to my BVA at some tau's (around a hundred seconds or so iirc.)  At times though the output seems to "jump" in frequency.   My other Z3805 from the same source doesn't work as well.

None of the 10811's in my various pieces of test gear (some of which I basically purchased to get the 10811's) worked all that well from an Adev perspective.  I used to buy HP5328 counters on the usual auction site with 10811's and the 500MHz C channel for quite low prices.    At least I still have a nice collection of frequency counters.


Sent from my iPad

On 2014-11-17, at 1:23 PM, Said Jackson via time-nuts <time-nuts at febo.com> wrote:

> Correct on all counts Bob.
> 
> My two 58503A units from China are great for both ADEV and PN measurements, better than anything else I have as a combo (I have Wenzel ULNs for even lower PN testing but they don't have any usable ADEV).  I also have a costly BVA and it can't compete against the HP unit.
> 
> Those 10811s just rule.
> 
> In fact my only complaint about the 58503A are the 60Hz related small spurs you can see in the plots...
> 
> Bye,
> Said
> 
> Sent From iPhone
> 
>> On Nov 17, 2014, at 12:28, Bob Camp <kb8tq at n1k.org> wrote:
>> 
>> Hi
>> 
>> The 58503 is a Z3801 with a pretty instrument style package put around it - right?
>> 
>> If so, it might / should  have a 10811 in it rather than an MTI OCXO. The 10811 is rated for -155 dbc at 100 Hz. That is much better than the noise floor that the MTI’s seem to produce at 100 Hz. About the only other GPSDO OCXO that gets to that level is the one in the original TBolts . There you very much have to deal with spurs. That make the noise floor of limited use in a practical system. 
>> 
>> Bob
>> 
>>> On Nov 17, 2014, at 2:26 PM, SAIDJACK at aol.com wrote:
>>> 
>>> 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
>>> 
>>> <DROR-IIA_Phase_Noise.png>
>> 
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