Said,
Thanks for the info and congrats on the stats from the Jackson Labs stuff.
You mentioned the older HP Z3801. I wonder if you (or others) happen to
have comparison numbers on the Z3816A with the MTI 260 oscillator or the
Z3805 with (I think) the same oscillator. I thought I heard the MTI 260
might be slightly better than the 10811 but can't recall if anyone here
actually made measurements,
Not to say that any of the HP Z---- stuff is seen for sale often these
days. But I have one of each of the above mentioned.
Guess it may be close to the *time* where I should take the *time* to
build or set up a system where I could get trustworthy measurements of
these *timing* quality things myself. I keep reading but never seem to
find the time to actually do it.
-Rex
On 6/3/2012 1:46 AM, [email protected] wrote:
Jerry, Chris,
it's all relative, while the Lpro may be a good Rb standard, it's phase
noise is not that good really. You list:
-96dBc/Hz @ 10Hz, -138dBc/Hz @ 100Hz, -152dBc/Hz @ 1KHz offsets
For the Lpro. The new Jackson Labs Technologies LN CSAC GPSDO with SC-cut
phase noise and ADEV filter achieves the following:
-138dBc/Hz @ 10Hz, -148dBc/Hz @ 100Hz, -152dBc/Hz @ 1KHz offsets.
At 1Hz offset we see -105dBc/Hz and better on that unit.
The FEI-5680A Rubidium that we discussed here some time ago has a much
worse phase noise plot of course, because the 10MHz is generated digitally
through a DDS, not a 10MHz crystal oscillator..
It all depends on your requirements, and your budget.. I think the Z3801A
(or it's brother the 58503A) is still one of the lowest phase noise and
best ADEV GPSDO on the surplus market if you get a typical unit, and if you can
locate one.
bye,
Said
From: Jerry Mulchin<[email protected]_ (mailto:[email protected])>
Date: June 2, 2012 16:44:14 PDT
To: Discussion of precise time and frequency measurement
<[email protected]_ (mailto:[email protected])>
Subject: Re: [time-nuts] GPS and Rubidium frequency standards and noise
question (newbie).
Reply-To: Discussion of precise time and frequency measurement
<[email protected]_ (mailto:[email protected])>
Chris,
To answer your question regarding using a Rubidium standard as a frequency
reference
for your Transverters.
GPS really has nothing to do the main requirement regarding Phase Noise
and your
Transceivers. But the 10MHz oscillator inside the Rubidium standard is the
item
that will be the Phase Noise problem if you get the wrong Rubidium
standard. There
are cheap Rubidiums and there are good Rubidium standards to consider.
An LPRO-101 is actually a very good Rubidium standard, and exhibits Phase
Noise
values of -96dBc/Hz @ 10Hz, -138dBc/Hz @ 100Hz, -152dBc/Hz @ 1KHz offsets
from carrier. This is what I use for my 10GHz Transverter reference, but I
don't lock it
to GPS when in the field. LPRO-101's can be gotten pretty reasonably.
Locking the LPRO-101 to a GPS will require more support circuitry, and
most of the
folks on this list can help you with that.
Also, Thunderbolt GPS disciplined units are nice, but I do not know the
Phase Noise
numbers of a typical Thunderbolt unit. Others here probably know the
answer to that.
The important thing to remember is you don't what to use 10MHz oscillators
that have
poor Phase Noise performance as it will effect your weak signal capability
if you use
a poor Phase Noise oscillator.
Jerry
At 03:05 PM 6/2/2012, you wrote:
If you want a frequency reference. There is nothing better than GPS. In
fact it you bought a Rubidium you would still need the GPS so you could
calibrate its frequency.
Some GPSes might be noisy but then you can lock a good double oven crystal
oscillator to it and have what they call a "GPS disciplined crystal
oscillator or "GPSDO".
On Sat, Jun 2, 2012 at 2:57 PM, Chris Wilson<[email protected]_
(mailto:[email protected])> wrote:
I am looking to get a frequency standard for my amateur radio shack,
initially for verifying test gear readings, but later as a standard
to lock receiver and transmitter oscillators to. I was going to buy
a GPS frequency standard but a friend warned me these may have noise
issues when I come to use it with an oscillator in RX / TX
applications. It's not something I had considered, so what's the
score here please? Should I not buy a GPS standard? Thanks. Any
links to known safe suitable purchase sources from personal
experience welcome, either here or by PM or e-mail. I am in the UK.
--
Best regards,
Chris Wilson _mailto:[email protected]_ (mailto:[email protected])
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