[time-nuts] [Bulk] ok, newbie questions

Fri Nov 26 10:35:10 UTC 2010

Eugene,

Welcome to the list and beware of how 'addicting' this can be.  I started
out with your exact same purpose, minus all the equipment you have, and am
still a 'newbie'.

First question is do you want a 'primary' standard (in essence, one that
does not need to be calibrated) or a secondary standard?  The two practical
choices for a primary standard are a GPSDO and a Cesium Beam Standard.  For
a secondary standard, Rubidium based oscillators or a good OCXO would seem
the most practical.

The Thunderbolt is a good choice and I do not know if the OCXO in the unit
will make a big difference for your purposes.  It does require +12 VDC, -12
VDC, and +5 VDC though.  I am not a big fan of switching power supplies for
this application.

The Z3805A requires only a single power supply and the Z3816A (at least) had
an option for 110 VAC.  It tracks 8 sats.  A single DC supply is likely the
easiest to build a battery back up for for continuous operation.

You can 'discipline' with a single sat once the site survey is complete and,
again, the number of sats is not likely to be an issue for your purposes.

You may have already found it but you might want to take a look at
http://www.realhamradio.com/ for additional information about the various
Z38xxA units.

Beware the shipping fees from Yixun.

And, finally, how will you know when your 'reference' fails?  You will
probably want to get at least one, if not two, additional units so you can
leave one running and have another you can bring on line in relatively short
order just to compare.

Hope this helps.

Joe

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of W2HX
Sent: Thursday, November 25, 2010 10:48 PM
To: time-nuts at febo.com
Subject: [Bulk] [time-nuts] ok, newbie questions

Hi all, I am sure my questions have been asked before. Unfortunately, the
mailman style archives are so hard to search through. So forgive me my
transgressions. Happy will I be to get a reference to an old thread that
answers my questions. Don't need new answers if old ones suffice. (of course
new answers always welcome!)

I am looking for a 10 MHz standard for my lab.  Accuracy/stability probably
wouldn't make a hill of beans difference in the stuff I do, so my questions
are more academic and it's just nice knowing I have a "really good"
standard.

1. So from reading about this topic on KE5FX.com I understand that a better
ocxo makes for better phase noise and near-term quality.  I also understand
that some later tbolts had a very good ocxo in them and therefore would not
benefit significantly from an upgrade as ke5fx did using an HP 10811 unit. I
am considering a thunderbolt advertised on ebay by "flyingbest." I will be
traveling to China (mainland, and Hong Kong) on business the last two weeks
in December so I might save some shipping.  Here is a photo. Can anyone tell
me if this unit has a  "better" 10811-class ocxo or "not so good "ocxo? I
also understand that not all ocxo's are created equal, even if they are the
same model number.

http://tinyurl.com/2dg2dz3

2. Other GPS DO units seem to differ on the number of satellites they can
receive from simultaneously (channels). What is the net effect of having a
standard that can see 6,8 or 16 birds? Is noise averaged out? Is
stability/phase noise improved? Here is an example of a 16 sat unit.  Anyone
have any experience with this unit? Good/bad indifferent? It seems they can
be had for about $200.

http://tinyurl.com/2ad5kls

3. And then there is the venerable HP units like this one.  I understand
this uses the 10811 ocxo. Other than the better ocxo, is there anything
inherently superior about these HP units to warrant the additional cost? Or
are we mostly just paying for the HP name?  This one is 6 sats.

http://tinyurl.com/24tkwdv

Lastly, my use of a 10 MHz standard will be for use in equipment like
microwave counters (EIP 548A), Spectrum analyzers (HP 8658B) VNA's (HP
3577A, 8753C to 6 GHz), synthesizer (HP 3326A and HP 8662A), premium
receivers (Harris 590H), etc., etc. For these purposes, is a GPS DO advised,
or perhaps a rubidium standard? For example, I don't need this to power a
clock. Just a good, clean, stable signal with low noise, low spurs, etc.

What's the overall opinion? THANKS !!!!

(here's to hoping this message looks better than the first two tests I made)
73 Eugene W2HX

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