Hi
The trick is that a good 125 MHz OCXO has better phase noise at 100 Hz than a
multiplied 5 or 10 MHz OCXO. By the time you get to 30 Hz, usually the lower
frequency
multiplied up wins. By the time you get to 3 Hz, the much higher Q HF OCXO
always
wins. (Yes, you could have a great 125 MHz
Hi Jim,
On 2019-02-13 14:24, jimlux wrote:
On 2/12/19 6:31 PM, Bob kb8tq wrote:
Hi
The normal approach as you head from HF up through stages to
microwaves is to stop
at various points along the way. Just where depends on the actual
noise you measure on
the sources you have. (Yes you have
On 2/12/19 6:31 PM, Bob kb8tq wrote:
Hi
The normal approach as you head from HF up through stages to microwaves is to
stop
at various points along the way. Just where depends on the actual noise you
measure on
the sources you have. (Yes you have to measure them yourself).
Once you have your
On 2/12/19 4:41 PM, Jeff Blaine wrote:
OK. I would still be interested to see if anyone has plots on the close
in noise profile of the Lucents. The XO part has an Efrom OCXO and I
can assume it's similar to a generic OCXO. But the RB is an unknown - I
have no idea what to expect from that.
Hi
You have a *ton* of digital this and that all on a common ground with the RF
output.
The original specs didn’t sweat the spurs so the designs are what they are. The
OCXO’s
are down in the -130 dbc/Hz range at 10 Hz offset. The Rb’s ten’s of db worse.
Nobody
seemed to mind ….
If you go
On some GPSDOs (like those made by Trimble that speak TSIP) you can disable
disciplining. Doing this usually reduces phase noise on the outputs, but in
this mode the frequency will drift over time. A lot of hams normally keep
disciplining on and turn it off when they are driving a radio.
OK. I would still be interested to see if anyone has plots on the close
in noise profile of the Lucents. The XO part has an Efrom OCXO and I
can assume it's similar to a generic OCXO. But the RB is an unknown - I
have no idea what to expect from that.
On a separate task, one of these days
kb...@n1k.org said:
> None of the GPSDOâs out there are great for multiplying direct to
> microwaves.
> Itâs not so much the phase noise as all the spurs (though phase noise does
> vary a bit).
Where do the spurs come from?
--
These are my opinions. I hate spam.
Hi
None of the GPSDO’s out there are great for multiplying direct to microwaves.
It’s not so much
the phase noise as all the spurs (though phase noise does vary a bit). For an
instrument frequency
source, they *assume* the input will be dirty and clean it up inside the
device. So again,
Hi Bob,
Thanks for your comments. The highest precision thing in my lab is a
5338a and that's only if I set the gate time to something really long so
that it renders a full 12 digits of info. Other than a "I wanna be a
time nut so let's see what it will do" - I never need anything near that
Hi
Pretty much all of these big old telecom beasts are “good enough” for “typical
use”. The gotcha
is that both of those terms are very much lacking in precision. Since this is a
precision sort of
thing, that may not be ideal :)
If 0.1 ppb is good enough for what you are doing, then they all
Am 12.02.19 um 03:57 schrieb Jeff Blaine:
I have these 3 systems operational here and wonder what is the "best"
of the sources?
The local use for the reference is as a time base for test equipment.
Nothing hyper critical in the way of end-use requirements - but after
running the NT GPSDO
I have these 3 systems operational here and wonder what is the "best" of
the sources?
The local use for the reference is as a time base for test equipment.
Nothing hyper critical in the way of end-use requirements - but after
running the NT GPSDO for a few years and watching the Lucent box
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