Didier Juges | 27 Apr 15:29 2015
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VFD wearout (was "dark display for 3458)

After the thread about the 3458 display, I went back to one of those VFD
that I mentioned in my earlier post. These had been used with only a few
digits turned on on the first line, the rest of the display being normally
turned off and only used occasionally. After several years of continuous
operation, the digits that were used  had lost brightness and more
interestingly, the other digits had also lost brightness but also looked
botched (the brightness was very uneven).

It turns out I have been using one of these old displays on a new project
(it's a development job, so the unevenness does not bother me at the moment
since this display will not ship). After about 2 weeks of continuous use
where most of the digits are used, the display is now just about back to
normal. somewhat dimmer than a new one, but the unevenness has completely
disappeared.

It looks like either the digits themselves, or the cathode wire, had become
contaminated as a result of not being used, and a few days of operation
restored their activity.

Even more interesting, at the moment, I cannot detect a difference in
brightness between the old digits that were on for several years and those
that were not. The display is generally dimmer than a new one, but the new
ones are a different part number, the original device having been
discontinued, so it may also be that the new display is brighter because of
process improvements by the manufacturer (something the manufacturer
advertised when they introduced the new device).

On this development job, most of the digits are used, and the display is
constantly changing (scrolling messages).

(Continue reading)

Frank Stellmach | 23 Apr 21:41 2015
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The Art of Electronics vs. Tietze Schenk

Hi,

I've got the German Tietze Schenk 6th ed. (1983, 850 pages), the latest 
14th ed. (2012, 1800 pages & DVD) and now also the AoE III (2015, 1190 
pages).

The Tietze Schenk served me very well  <at>  university, letting me develop 
several very precise AC and DC current sources from the more or less 
theoretical circuits.. The Tietze Schenk may be more academic and goes 
more deeply into the theoretical background.

The AoE, I did not know before, is much more fun, due to its vivid 
style, and also gives quite good theoretical background, compared to  T 
& S.
But I really dig these "best in class" used cases from the HP 
instruments, for example.

I've learnt a lot from these Fine Arts HP schematics, so this idea of 
AoE is really great.

The AoE III is relatively cheap here in Germany (around 66€), because we 
otherwise have a price binding here, for domestic books.

I'm glad, having both electronic bibles, complementing each other.

Frank
Frank Stellmach | 23 Apr 21:19 2015
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Advise to Junior Member Regarding Acquisition of Fluke 5XXX Series Calibrator

Hi Stan,

the 720A can easily be replaced by an HP3458A, which is superior to the 
KV divider in several aspects.

First, the 3458A has 3-10 times better linearity, 0.02ppm (typ.) of F.S. 
compared to 0.1ppm of input for the 720A.
Therefore, a 10:1 transfer is accurate to 1ppm for the 720A only, 
whereas the 3458A manages 0.1 to 0.3 ppm.

The self calibration is much easier on the 3458A, as are all these 
calibration measurements, you mentioned.
(Fluke has published a good application note, how to replace their own 
old style equipment as KV, Null VM, etc. by their own 8 1/2 digit 8508A).

And you may get a very reasonable and recent instruments for 3000$/€, 
maybe much less for older ones.

A calibrator is limited in use, as it needs a Null VM at least.

Anyhow, I recommend the Fluke 5440A / 5442A DCV calibrators.

They are ultra stable, having 2 stacked SZ263A references inside, good 
for 732A stability.

Their D/A is also extremely linear, I measured something like 0.2ppm INL 
against my 3458A, and they are spec'd to 0.5ppm of output, also superior 
to the 720A in some volt areas.

They also have this handy autocal function (like the 3458A) for the 4 
(Continue reading)

Frank Stellmach | 23 Apr 21:27 2015
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HP 3458A user-defined keys

Hi Steve,

according to the manual, DEFKEY is also accessible from the front panel.

I assume, you may just assign the wanted functions by accessing the 
normal command menu, after entering "DEFKEY x,"

Anyhow, programming the keys via GPIB is much more handy..

Frank
STEVE REEVES | 23 Apr 19:08 2015
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HP 3458A user-defined keys

  Hi.

 I want to set up some user-defined key functions for my 3458A. I previously read where this can be done only
over GPIB control - is that correct? Can it be done from the front panel?

I want to set up the following 2 separate keys:
Null
dB

Steve
Marv @ Home | 23 Apr 17:35 2015
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Re: Transmille 8081

Some points of interest:

http://www.eevblog.com/forum/testgear/8-5-digit-dmm/msg527708/#msg527708

http://bbs.38hot.net/thread-719-1-1.html

http://www.eevblog.com/forum/testgear/8-5-digit-dmm/?action=dlattach;attach=56377;image

Beyond specs, another consideration is total ownership cost: 
calibration & repair.

Stan Katz | 23 Apr 06:24 2015
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Advise to Junior Member Regarding Acquisition of Fluke 5XXX Series Calibrator

I have now been disappointed three times with Ebay 720a's. All were DOA
completely or failed self-calibration horribly. These 720a's were sold by
individuals at around the $1000USD mark.

I can purchase a refurbished and guaranteed 720a for around $3000.00. If
one is establishing a modest, and easy to keep in repair home metrology
lab, maybe an older Fluke 5000 series calibrator is the way to go? The
older calibrators are being offered, again by individuals, or surplus
businesses, for around $950USD.  The guaranteed working 5440b's go for
$2000USD without calibration.  There may be more hope, that a used
calibrator, with its built in protective circuitry, can be purchased
surplus with more success than the 720a. The 720a divider resistors are too
easily cooked by idiots. In addition, from my own sad experience, the
sealed "A" switch on the 720a has a much shorter lifetime than the open
wafer switches. Thus, even the refurbished 720a may suffer an "A" switch
failure shortly after the warranty period expires.

IMHO,  a 720a only makes sense if you buy new for business purposes.

Why have I felt the need for a 720a?
1. My 731B calibration procedure calls out a 720a.
2. I have a Fluke 750 divider that I acquired to calibrate my HP3456A
voltmeter. The 750 divider manual calls out a 720a for its calibration.
3. Procedure for calibrating my HP735A to 1v +/- 2ppm from my Fluke corp.
calibrated 731b calls out a Kelvin-Varley Divider.

Can a Fluke 5000 series calibrator take the place of a Kelvin-Varley
divider in all of the above procedures?

Suggestions Welcome,
(Continue reading)

John Phillips | 21 Apr 22:49 2015
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Transmille 8081

Does anyone have any input on a Transmille 8081
From what I can see it looks as good or better than a 9458A

--

-- 

*John Phillips*
Marv @ Home | 19 Apr 03:03 2015
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Re: The Art of Electronics

Orin, that's a great resource, thanks a bunch.  I forgot all about 
Abe's Books.  AoE 2nd Edition Int'l version new in $10-15 range.

At 05:15 PM 4/18/2015, Orin Eman wrote:
>Try searching for the T&S V2 ISBN,
>
>3540004297
>
>on www.abebooks.com
>
>$40 for the International Edition from a somewhat reputable seller.
>Since this is an international list, I have no qualms about passing
>this on.  Whether you can stand the almost transparent paper and
>smudgy ink is a different matter.
>
>Orin.

Andrea Baldoni | 17 Apr 09:44 2015

The Art of Electronics

Hello.
In the case someone missed the new, after years of waiting, the third edition
of the book in the subject is out!

I'm a true fan of the second edition and I'm sure I will not be disappointed
by the new one; I should receive it in the beginning of the next week so if
someone is interested in details, feel free to ask.

Best regards,
Andrea Baldoni
Tom Knox | 16 Apr 05:08 2015
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Re: HP-3458a display board

Hi Randy;
I saw the same thing, That is a great deal, I though they were much more expensive. Even at half the price I
would use the Keysight exchange program since they recently started offering free courier pick up, In
addition you would have a warranty and most likely have a new VFD.
Cheers;
Thomas Knox

Ascent Concepts and Technology

4475 Whitney Place
Boulder Colorado 80305

1-303-554-0307

> Date: Wed, 15 Apr 2015 14:39:38 -0700
> From: randyevans2688@...
> To: volt-nuts@...
> Subject: Re: [volt-nuts] HP-3458a display board
> 
> FYI,
> 
> I contacted Keysight and found the exchange program is still in place.  The
> PN is 03458-69517 and the price is $278.
> 
> Randy Evans AE6YG
> 
> On Wed, Apr 15, 2015 at 12:05 PM, Randy Evans <randyevans2688@...>
> wrote:
> 
> > I need to replace the display board for my HP-3458A (several dim to
(Continue reading)


Gmane