[time-nuts] Symmetricom X72

WB6BNQ wb6bnq at cox.net
Sat Jul 24 16:20:42 EDT 2010


Heathkid,

You got to be kidding ?

I am guessing, from your comments, that you need to do a bunch more reading and
pondering on the subjects of stability, accuracy and making those measurements.
Especially before tossing the FEI-5680's in the trash.

The FEI-5680A is a nice unit, you just have to understand what you have and how
to apply it.  Assuming that the FEI-5680 is working correctly, it will be more
stable then most crystal oscillators found in the all but the very higher quality
frequency counters.

In comparison to your TCXO, the FEI-5680 would be 3 orders of magnitude (i.e., 3
more decimal places or a 1000 times) more stable.  And likely a hell of a lot
closer to the proper reference too.

Until you have a measurement system that is known to be more accurate then the
FEI-5680, there is no way to say it is a mistake.  So, two primary components are
at hand here; first being stability and the second being accuracy.  Even if it is
not SPOT on accurate with a world reference does not make it UN-usable as
stability would be the more sought after parameter in any case.

So, I disagree with your premise,

Bill....WB6BNQ


Heathkid wrote:

> Hello Bob,
>
> What would you recommend?  I already have three FE-5680A Rb standards (which
> I'm quickly learning likely aren't worth the powder to blow them to (*insert
> your own word here*).  Okay, that was probably my first mistake (thoughts?).
>
> My frequency counter is one I built from a kit from aade.com that has the
> TCXO option (although I had to tweak it myself so I have NO idea how close
> it is to any accuracy or precision).  I have access to some really nice HP
> counters at work so that's my next step is to try one of those.  My DFD4
> measured the output of one of my 5680A's to 10.000.007 MHz after about a 10
> minute warm-up.  I don't know which one is off.  Reading the specs on the
> 5680A's before I bought them looked like they were pretty decent.  I'm
> learning...
>
> So, what "reasonably priced" Rb standard would you recommend?
>
> Should my next step in this process be a Trimble Thunderbolt?  Am I starting
> over?
>
> Thanks...
>
> ----- Original Message -----
> From: "Bob Camp" <lists at rtty.us>
> To: "Discussion of precise time and frequency measurement"
> <time-nuts at febo.com>
> Sent: Saturday, July 24, 2010 9:31 AM
> Subject: Re: [time-nuts] Symmetricom X72
>
> > Hi
> >
> > At least looking at the spec sheet it's not really very impressive.
> >
> > Bob
> >
> >
> > On Jul 23, 2010, at 11:06 PM, Heathkid wrote:
> >
> >> Hello.  Does anyone have any experience with the Symmetricom X72?
> >>
> >> Thanks...
> >>
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