[volt-nuts] 3458A reference boards on ebay

[Bill Gold]

----- Original Message ----- 
From: "Dr. David Kirkby (Kirkby Microwave Ltd)"
<drkirkby at kirkbymicrowave.co.uk>
To: "Discussion of precise voltage measurement" <volt-nuts at febo.com>
Sent: Tuesday, January 27, 2015 2:24 AM
Subject: Re: [volt-nuts] 3458A reference boards on ebay


> On 27 January 2015 at 09:16, Orin Eman <orin.eman at gmail.com> wrote:
> > There is a seller letting a slow trickle of them out there... they seem
to
> > be going for about $165.  The current batch of two is around $100, but
will
> > probably be bid up.
> >
> > I just received one that I won.  Seems to be working fine after a quick
> > breadboard lashup.  I'll be making an enclosure for it next.
> >
> > A little expensive IMO, but given the trouble getting the precision
> > resistors to DIY with the LTZ1000A, probably worth it.
> >
> > Orin
>
> Orin,
>
> What do you intend doing with it?
>
> I was thinking about getting one of those, with a view to putting it
> in a box with a couple of terminals to have something to compare with
> my 6.5 digit 3457A.  But what put me off is a lack of knowledge in
> knowing how to convert a 3458A reference board into a boxed unit with
> a known output voltage at the terminals. How would I avoid / control
> thermal EMFs?
>
> I'd be interested to hear what your plans are for it, and how you
> intend tackling those issues.
>
> Do you know what the difference in the reference is between a standard
> 3458A (8 ppm) and the high stability option 002 (4 ppm) model? I'm
> guessing the chips for the option 002 might be the top performing
> ones. I wonder if there's any way to tell from your board if it came
> from a standard 3458A or a 3458A with option 002.
>
> Dave

Dave:

    The 002 reference boards have another label on them marked 03458-66519
which overlays the etched number on the PC board.  As a matter of fact see
the new listing on evilbay 271754789913.  The super ultra stable 2ppm is
marked 03458-66529 to the best of my knowledge.

Bill

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