[time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812...
Bob Camp
kb8tq at n1k.org
Mon Nov 17 16:19:03 EST 2014
Hi
I would pretty much ignore any 60 / 120 / 180 Hz spurs in a US phase noise plot. The same thing would be true of 50 / 100 / 150 Hz spurs from a country that uses 50 Hz power. Unless everything is running in the middle of a corn field on batteries, there is no way to be *sure* that they are not part of the measurement setup.
If you happen to be on a circuit with heavy rotary machinery, you can see artifacts at 1/2 or 1/3 or 1/4 the power line frequency. I doubt that in that case the bearings on the equipment are going to last very long. They rarely are strong enough to bother a phase noise plot, but I have had it happen.
Bob
> On Nov 17, 2014, at 3:01 PM, Tom Miller <tmiller11147 at verizon.net> wrote:
>
> That first spike falls right at 60 Hz. I wonder if your test setup is picking up some hum?
>
> Tom
>
> ----- Original Message ----- From: "S. Jackson via time-nuts" <time-nuts at febo.com>
> To: <kb8tq at n1k.org>; <time-nuts at febo.com>
> Sent: Monday, November 17, 2014 2:26 PM
> Subject: Re: [time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A,Z3811A, Z3812...
>
>
> 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
>
>
>
>
>
> --------------------------------------------------------------------------------
>
>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
More information about the time-nuts
mailing list