[time-nuts] Recommendations for a newbie?

[SAIDJACK at aol.com]

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.com discusses 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