[time-nuts] Recommendations for a newbie?

Azelio Boriani azelio.boriani at screen.it
Fri Sep 7 20:58:34 UTC 2012


Good one, the HP58503A, actually it is my reference at work.

On Fri, Sep 7, 2012 at 10:37 PM, <SAIDJACK at aol.com> wrote:

> Hello Robert,
>
> your question is like asking which car you should buy, or which airline you
>  should fly :)
>
> Everyone will have a different answer.
>
> But I do not recommend the Thunderbolts, it's a crab-shoot with them
> (different versions have different performance, the new ones are  actually
> worse
> than older versions because of the temperature chip  issue, the GPS is
> known
> to have lock issues, they don't work well until you  spend a lot of time
> fine-tuning the parameters, etc etc) - that has all  been discussed here
> ad-infinitum and you can find it in the archives.
>
> I recommend you search Ebay for HP 58503A. I just bought a number of them
> from a very well known seller in China, and they are absolutely  superb,
> much better than any Rubidium unit I have tested. Much better  than the
> Thunderbolt I have, and just slightly more expensive. He sells an  entire
> kit for
> around $500, and it arrived here in less than a week (Northern
>  California).
>
> This seller starts those units at around $260 I think. Performance you can
> get from these if you get a good one is: phase noise floor of  around
> -163dBc, ADEV of 7E-013 to about 1E-012 to over 100s. Leapsecond.com  has a
> number of test papers on these units. Caveat-emptor: there are significant
> unit-to-unit variations as with all GPSDO, Tom on leapsecond.comdiscusses this
> in detail. BTW: these are essentially the same unit as the Z3801A, just
> different software (ID string).
>
> I also have a Z3815A, and it is not even in the same class as the
> Z3801A/58503A. It is very noisy compared to the 58503A unit. I do not
>  recommend the
> Z3815A, but it is a unique oscillator design,and some folks  collect it for
> that oscillator. The 58503A uses a double oven version of the HP  10811A,
> which is a fantastic oscillator if you get a well-working one.
>
> If you want something low-cost with reasonable performance, brand new  with
> warranty, antenna, and accessories, Jackson Labs Technologies, Inc.  has
> the GPSTCXO eval kit for Time-Nuts special academic pricing of $300, which
>  we
> believe is the lowest-cost true GPSDO (not NCO) in current  production.
> Disclaimer: I work for them.
>
> bye,
> Said
>
>
>
>
> In a message dated 9/7/2012 13:09:24 Pacific Daylight Time,
> azelio.boriani at screen.it writes:
>
> Welcome  aboard,
> yes, there is no FAQ about how to start in this hobby... should I  try to
> implement one? Anyway, start with a Trimble Thunderbolt (aka TBolt),  later
> you will know why it is highly recommended (direct OCXO disciplining  and
> LH
> software support, mainly). I have a Z3815A with the famous (or  infamous)
> E1938A "hockey puck" OCXO. They are all GPSDOs and there should  not be any
> difference among them but, yes, there are differences in their  performance
> and being a time-nut means test and find out. Then there are  GPS
> disciplined Rubidiums, but take this step after the first GPSDO  is
> correctly installed and stabilized. Start with the antenna: find a
>  suitable
> place, with a 360 deg clear view of the sky, a satellite TV cable  (sounds
> unusual, but works great).
>
> On Fri, Sep 7, 2012 at 8:52 PM,  Robert Darlington
> <rdarlington at gmail.com>wrote:
>
> > You want to  start with a GPSDO.  I like the Trimble Thunderbolt.  The
> >  price is right and they're readily available.  I have no  experience
> > with the HP units but they seem to be highly  regarded.
> >
> > Rb oscillators are great for some things, but need  to be calibrated.
> > That's where the GPSDO comes in.
> >
> >  Also, don't forget the antenna.   You'll want something along  these
> > lines:
> >
>
> http://www.ebay.com/itm/lucent-GPS-Timing-Reference-Antenna-antenne-40db-N-/230848464732?pt=GPS_Antennas&hash=item35bfa4075c#ht_2199wt_1404
> >
> >  Welcome aboard, and I'm apologizing in advance for how much money
> >  you'll be spending on new toys.
> >
> >  -Bob
>
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