Re: [volt-nuts] Neon bulbs for HP 3420B or 419A chopper circuit

[Pete Lancashire]

sorry got it upside down must have been lost in the translation :-)

so you need some 'good old' NE's. If you can find some in the UK/EU I can
send you a few.

-pete

On Thu, Nov 16, 2017 at 1:08 PM, David C. Partridge <
david.partri...@perdrix.co.uk> wrote:

> Errm  - I'm looking for around 65-75V range so I end up near but not
> exactly the same as the 70V ones that are already there.
>
> -Original Message-
> From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of Pete
> Lancashire
> Sent: 16 November 2017 18:24
> To: Discussion of precise voltage measurement
> Cc: hp_agilent_equipm...@yahoogroups.com
> Subject: Re: [volt-nuts] Neon bulbs for HP 3420B or 419A chopper circuit
>
> I've seen 95V but nothing as high as 125V.
>
> The high brightness ones are usually 95V
>
> http://www.farnell.com/datasheets/57560.pdf
>
>
> -pete
>
>
> On Thu, Nov 16, 2017 at 6:38 AM, David C. Partridge <
> david.partri...@perdrix.co.uk> wrote:
>
> > In an earlier post I quoted the following description of the
> > photo-chopper circuit from the 419A manual
> >
> > 4-43.   Assume that DS1 lights when the input is applied to T2.
> Capacitor
> > C1 charges until the oscillator switches the input, and DS1 goes off.
> >  When
> > the oscillator switches again, the charge on C1 insures that DS2 fires,
> and
> > DS1 stays off.   This cycle continues with DS1 and DS2 firing as long as
> > there is output from the oscillator.  CR1 and CR2 prevent the
> > capacitor from discharging through R1 and R2
> >
> > That description also applies to the 3420B chopper.
> >
> > For this to work as described, George Einst says that the striking
> > characteristics on the neons are critical, which I totally believe
> > given what's happening in mine.
> >
> > AFAICT, *both* neons are striking on every +ve portion of the square
> > wave drive signal, so the flip-flop behaviour doesn't happen.
> >
> > I checked on the curve tracer, and both neons strike at almost exactly
> 70V.
> > Both are also totally clear which suggests to me that they are not the
> > originals.
> >
> > Does anyone have any idea how much the strike voltages would need to
> > differ for this to work, and does anyone have any suitable neons - the
> > only ones I have are these shorter ones and they strike at about 125V.
> >
> > These are the longer bodied neons (glass about 5/8" long).
> >
> > Thank you
> > Dave Partridge
> >
> >
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Re: [volt-nuts] New scan of Solartron 7081 Service Manual is now available.

[Pete Lancashire]

I for one want to say a big Thank You to Dave for the scans.

-pete

On Tue, Jun 14, 2016 at 5:27 AM, David C. Partridge <
david.partri...@perdrix.co.uk> wrote:

> Now updated
>
> -Original Message-
> From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of David C.
> Partridge
> Sent: 14 June 2016 10:41
> To: 'Discussion of precise voltage measurement'
> Subject: Re: [volt-nuts] New scan of Solartron 7081 Service Manual is now
> available.
>
> A quick update, I just noticed that I hadn't cleaned up all the scans of
> the mechanical drawings (I thought I'd done all of them).
>
> I'll clean those up and re-post the document.
>
> Dave
>
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Re: [volt-nuts] Hello and relay card for HP 3457a

[Pete Lancashire]

The scanner that came out the same time is the 3488A

http://www.rlscientific.com/documenti/HP3488A.pdf

The above PDF is from an HP catalog.

http://www.helmut-singer.de/pdf/hp3457a.pdf

The 2nd half is in English

On Thu, May 12, 2016 at 9:16 AM, Jerry Hancock <je...@hanler.com> wrote:
> I think the card that goes in the dedicated scanner made by HP that looks 
> like the 3457, can’t remember the number but I have one, also fits.  I think 
> I paid less than $35 for my scanner shipped.  I also think the display in 
> that unit fits the 3457 and the 3478 but never took a hard look at it.
>
>
> On May 11, 2016, at 2:44 PM, Pete Lancashire <p...@petelancashire.com> wrote:
>
>> Unless someone has one and is up to selling it, my thoughts would be
>> to set up a user defined search on the big auction site and have it
>> notify you. Like anything if you are not in a rush you can like just
>> about everything get one for a pretty good price. If in a rush expect
>> to pay around $200-250 for either the 44491A or 44492A with the
>> terminal block.
>>
>> And like any mechanical relay based scanner/card/etc be prepared to
>> have to replace relays. Luckily HP used ones that are easy to get. The
>> thing missing for me
>> with the 3457A is a low noise mux using parts like Hg wetted relays.
>>
>> Space has not been an issue for me, I use 3497A's and/or VXI for
>> building up scanners.
>>
>> On Wed, May 11, 2016 at 1:55 PM, lincoln <linc...@ampmonkeys.com> wrote:
>>> Hello,
>>>I have been a long timer lurker of the list via the archive. It was 
>>> a big help getting my Ebay 3457a up and running.
>>>
>>> Now I hate to be that guy that joins the list and then BAMB tuns around as 
>>> asks a favor but i'm afraid I have to be that guy. I am looking for a relay 
>>> card for the 3457a. I need to set up a board level tester and the internal 
>>> scan card would simplify things quite a bit.
>>>
>>> Ether relay card would work, I'm happy to pay for the card or trade for the 
>>> rear terminal card and cover shipping.  (I'm in CA USA)
>>>
>>> I have been looking on ebay as well. If a unit come up I will jump on it. A 
>>> detected switch unit is also a less than ideal option but so be it.  One 
>>> way or another the tester will get put together.
>>>
>>> Thank you for your time.
>>>
>>> Link
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[volt-nuts] Before I order the connector for the Solartron 7081 ....

[Pete Lancashire]

Anyone recommend a North American source ? or have one they are not using ?

And where asking, any metrology shops one can recommend ?

-pete
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[volt-nuts] 1/2 OT: Looking for info on Shalltronix standards

[Pete Lancashire]

Anyone have any old spec/catalogs/etc ?

Interested in their 271 series

And would like to scan any catalogs for my eventual web site

-pete
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Re: [volt-nuts] New member with 3457A problem

[Pete Lancashire]

Seen a lot worse even on rentals.  Pretty much the same here, other big $
projects going on right now so can't make an offer.



On Tue, Jan 5, 2016 at 5:28 PM, Tom Miller  wrote:

> That looks like a good one from what I can see. It would be nice to check
> it out in person to see if the display has any dim digits. Looking at the
> picture seems to show it has some dimming compared to the manual range
> indicator. The price is pretty good also. Maybe they might negotiate down
> slightly.
>
> It would run you about $600+ to send in for a Keysight calibration.
>
> Nice work on finding the problem with your 3457A.
>
> - Original Message - From: "Jerry Hancock" 
> To: "Discussion of precise voltage measurement" 
> Sent: Tuesday, January 05, 2016 8:06 PM
> Subject: Re: [volt-nuts] New member with 3457A problem
>
>
>
> Hello again, Just for the record, after spending another dozen or so hours
>> on this problem, I found U216, “Precharge offset adj” to have a low
>> resistance from pins 1,5,6 to pin 4, essentially one of the 4 transistors
>> in the CA3096 is shorted (11.28 ohms) though not completely.  I found this
>> by scoping the signal coming into the input amplifier at pin 10 of U101,
>> “Input Hybrid”, while putting the meter into an auto cal loop.  This
>> problem was difficult to track down as unlike the other Service Manuals,
>> there are no waveforms available in the 3457a manual.  I noticed that
>> during the precharge cycle the waveform was taking a large negative dive
>> instead of two relatively equal pulses, one that reads the signal and the
>> other during precharge, I assume.  This negative voltage from the precharge
>> offset was then not being drained efficiently when the leads were open
>> resulting in a negative to zero open voltage displayed on the meter
>> compared to the typical ~+2.5V.
>>
>> So for the record, if you get a “0 Hardware error” followed by a 512 or
>> 560 (512 + 32 + 16 errors signaled) in reply to the “auxerr?” command, take
>> a look in the area of U216 and check the four transistors that are in the
>> CA3096E.
>>
>> Lastly, as I commented on another site, after reading through the 3457a
>> theory of operations, that there are a number factors that need to be
>> calibrated out of a meter to ensure accuracy and repeatable measurements.
>> In this case, obviously the input amplifier needs to have a stable offset
>> voltage (zero).  The precharge offset charges the approximate 10pf of stray
>> capacitance out of the input amplifier to keep it from impacting the
>> readings.  In conclusion, it takes more than an accurate ADC, gain
>> resistors, etc to make a good meter.  I followed a number of threads where
>> people were attempting to make their own 5.5 digit meter, I played around
>> with some circuits myself, but nowhere did I see stray capacitance taken
>> into account.
>>
>> Thank you for reading.  By the way, there is what looks like a nice 3458a
>> on craigslist in the SF Bay area.  Initial price of $2,900 was dropped last
>> night to $1,950.  I wish I had some leftover cash from Christmas!
>>
>> Jerry
>>
>> On Jan 3, 2016, at 6:26 PM, Jerry Hancock  wrote:
>>
>> I’ve been reading the list for a while, never had a reason to post until
>>> now.
>>>
>>> I have an HP 3457a, actually two of them, both work great, accurate,
>>> stable, etc., except one won’t autocal without an error 512 in auxerr -
>>> ohms recharge offset.  I’ve had the meters side by side for hours the past
>>> few days and can’t seem to locate the problem.  There is a difference in
>>> the Ohms precharge offset in the failing meter.  It looks like a factor mod
>>> was performed to lower U216 below +15 by adding resistors to legs 13 and
>>> 10.  I know there were service notes sent out by HP in 1992 related to the
>>> 512 error. the other thing of note is that occasionally when I power on the
>>> meter, it will also get a 16 error, which is the offset.  I ran diagnostic
>>> 4 and calibrated the offset but occasionally the meter will not pass the
>>> test no mater how the offset it adjusted.  For those of you not familiar,
>>> the diagnostic 4 puts the meter in a loop displaying HI or LO depending on
>>> the adjustment until the repair tech (me in this case) adjusts the offset
>>> correctly.  At that point the
>>>
>> meter displays ‘Passed’.  When the meter fails, usually when cold, the
>> display oscillates between HI/LO like the ADC doesn’t have a connection and
>> the input is floating.  I tried swapping U101, the input hybrid, between
>> the two units without luck.
>>
>>>
>>> So I am wondering if anyone on the list has run into this problem in the
>>> past, and if so, the solution would be appreciated.
>>>
>>> Thanks.
>>>
>>> By the way, I have a number of voltmeters, can’t seem to get enough, and
>>> am pretty good with 3455A repairs having four of them.  My black face 3455A
>>> is one of my favorites.  I also 

[volt-nuts] Scan of L 1972 Catalog - Section J - Test & Calibration Equipment

[Pete Lancashire]

For the Resistor Nuts among us

>From one of the past leader. Not sure if they did anything in the
way of standards, dividers, etc after this catalog was published.

https://goo.gl/0YMu9T

Kind of large, 150 MB I'll see about shrinking it.

-pete
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Re: [volt-nuts] Differential amplifier >=1Mhz

[Pete Lancashire]

The problem is a stand alone diff amp is going to be a low volume thing to
sell

Two of the best ones (one no longer made) are the Preamble DA1820/1822(A)
and DA1855(A)

http://cdn.teledynelecroy.com/files/manuals/da1820-1822_om.pdf

They were bought out by LeCroy and then LeCroy by Teledyne.

The 1855 (and 1855A) sell for quite a bit expect to pay around $1000 for
one.
I've seen 1822's for less the $200 but you have to have auto notify on the
auction sites set up.

I got one on the big auction site for $100 as a Buy-it-now. But that was
just luck.

Outside of the physics/chem/bio market there isn't anything.. a quick scan
on Google

http://www.tegam.com/product.asp?modelNumber=4040B

https://www.a-msystems.com/s-130-acdc-differential-amplifier-model-3000.aspx

http://www.bakelectronicsinc.com/2-3.html







On Mon, Nov 23, 2015 at 12:00 PM, Andrea Baldoni 
wrote:

> On Mon, Nov 23, 2015 at 07:06:59PM +, Mark Sims wrote:
>
> > Maybe a Tektronix AM502 module and the single slot TM501 mainframe?
>
> Hello Mark.
>
> Yes, the AM502 is the thing I am searching, but they are not very cheap for
> a 1977 vintage, in particular adding the mainframe.
>
> It's possible that in 38 years no maker did anything like?
> Looking better, all other modules I saw aren't equipped with front panel
> output,
> because are in effect vertical oscilloscope amplifiers and thus the output
> is
> on the backplane. And they are not cheap also.
>
> Best regards,
> Andrea Baldoni
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[volt-nuts] Just A FYI _ One the big auction site a Datron 4902

[Pete Lancashire]

No assoc with the seller etc

-pete
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Re: [volt-nuts] any voltnuts in the Chicagoland area?

[Pete Lancashire]

Interesting idea a voltnuts location database
On Sep 30, 2015 12:34 PM,  wrote:

> I am looking for fellow voltnuts in the Chicagoland area to share
> calibration, voltage standards, etc...
>
> This hobby can get quite expensive when the costs don't get shared...
>
> Please reply to the list or direct via e-mail...
>
> Thanks
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Re: [volt-nuts] Fluke 760A Calibrator offered FOC

[Pete Lancashire]

Phew... saved. BTW on YouTube there is a video of a 760 being taken apart.
Comment trail indicated he was willing to send parts for shipping.
On Aug 9, 2015 4:33 AM, Nigel Clarke via volt-nuts volt-nuts@febo.com
wrote:

 The 760A is now spoken for subject to collection, I'll post again if
 there's any change to that.

 Regards

 Nigel
 GM8PZR


 In a message dated 07/08/2015 01:28:02 GMT Daylight Time,
 volt-nuts@febo.com writes:

 I have a  Fluke 760A calibrator, complete with original manual including
 schematics etc, that I haven't powered up for a few years but as best  I
 remember was working last time I tried it.

 This is  available free of charge to anyone willing and able to collect
 from
 the  west coast of Scotland.

 It's far too heavy to ship and should be  accepted as is, I won't be
 testing
 it again as I don't have time to get  distracted chasing any problems that
 might   arise.

 Regards

 Nigel
 GM8PZR
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Re: [volt-nuts] Precision resistors

[Pete Lancashire]

Since R is quite tied to E, i found this paper to be quite interesting

... Pettis was also the resistor expert who worked with Bob Pease in his
last project trying to push the state of the art at the time for special
resistors needed on the project.
The invention of Evanohm 

http://www.edn.com/design/analog/4427151/The-last-half-century--Wirewound-resistors-Part-one

http://www.edn.com/design/analog/4427940/1/The-last-half-century--Wirewound-resistors-Part-two





On Thu, Aug 6, 2015 at 1:44 PM, Richard Moore richiem5...@gmail.com wrote:

 Check with Edwin Pettis at Ultrohm in Grand Junction, Co. H ewinds superb
 ww resistors using Evanohm wire with tempcos under 3ppm/degC, with 0.01%
 tolerance for around $14 each. I’ve bought some and have been extremely
 pleased. Don’t know the largest he can make or at what price…

 pettis...@q.com

 Dick Moore


  Message: 1
  Date: Thu, 6 Aug 2015 16:25:54 +0100
  From: David C. Partridge david.partri...@perdrix.co.uk
  To: 'Discussion of precise voltage measurement' volt-nuts@febo.com
  Subject: [volt-nuts] Precision resistors
  Message-ID: 5D9EFA13BAB94DCA901607C1EDEA4911@APOLLO
  Content-Type: text/plain; charset=UTF-8
 
  Looking for a set of precision resistors for calibration purposes.
 
  I need the following values to calibrate the ohms ranges on my meters:
 
100
1k
2k
10k
20k
100k
200k
1M
2M
10M
20M
 
  The crucial factor isn't that they be *exactly* the values above, so I
 don't necessarily need 0.001% parts.  Low TCR is important, and I will need
 to know that actual values to 10ppm or better.
 
  I'm looking for suggestions on the best choice of parts and pricing?  I
 believe the Vishay HZ series may fit the bill for the lower values but they
 may be rather expensive.
 
  Regards,
  David Partridge

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Re: [volt-nuts] HP-419 and Fluke 845 Modifications

[Pete Lancashire]

I have used 845As and other instruments recorder output voltage to
digitize what I'm measuring. I'm surprised the 419A doesn't. I just
never looked before. So not like HP, I'm glad your considering adding
one.

On Mon, Dec 1, 2014 at 11:40 AM, Randy Evans randyevans2...@gmail.com wrote:
 Dave,

 The HP-419A is driving the need for an isolated recording output (it
 doesn't have one in the basic unit) and I wanted to provide one.The
 circuit is being designed to work with either the HP-419A or the Fluke
 845A.  The isolation circuit does not have to be used if not wanted since
 it is a completely separate circuit and not needed for the meter to work.
 I still need to work on the final HP-845A modifications and i will look at
 your suggestions.

 Randy

 On Sun, Nov 30, 2014 at 6:37 PM, Dave M dgmin...@mediacombb.net wrote:

 Randy,
 Thanks for continuing with this modification.

 Speaking of the Fluke 845A;
 At first glance, you could probably leave the existing power supply
 inverter circuit intact, as well as the isolation transformer for the
 recorder output, with the recorder output transformer being driven (at the
 center tap) by the output of the last DC amp stage of the null amp
 circuit.  That would maintain the isolation of the meter and recorder
 output, and eliminate the need for an extra amp for them.  It would also
 maintain the guard integrity, keeping the instrument's operational
 characteristics as close to original as possible.
 By leaving the existing inverter circuit in place, you can easily derive
 any voltages (+ and -) that your mod needs from it, without the need for
 additional isolated power supplies

 Dave M



 Randy Evans wrote:

 I finished the H-419A/Fluke 845A design modifications but I am still
 trying to decide on the preferred power supply design.  The basic
 meter circuit uses the LTC2054 and LTC6255 with two CR123 Li-Ion 3 V
 batteries.  The
 basic meter circuit draws less than 0.2 mA and with 1500 mAH CR123A
 batteries should be able to go several thousand hours on a set of
 batteries.   For the meter circuit, it is always battery powered and
 doesn't have to be plugged into the mains.

 I also added a TI  AMC1100 isolation amplifier for recording output
 but it needs a 3.3 VDC isolated supply and a 5VDC output supply.  The
 current design  uses separate isolation power supplies using  LT8300
 ICs that work off the mains transformer so there would be no worry
 about failing batteries.  Therefore, to use the recorder, the unit
 would have to be plugged in. I am trying to decide if it would be
 simpler to use batteries for the isolation circuit as well. If I use
 batteries, do I use rechargeables or non-rechargeable batteries such
 as the CR123s?  The
 circuit would need one set for the input isolated circuit side and
 another set for the recorder output side and the batteries would not
 last as long
 as the meter circuit since the isolation circuits draw about 12
 milliamps. They would still work about one hundred hours most likely
 and would not
 draw any current unless the isolation circuit is turned on (with a
 separate toggle switch).  My preference is to stay with the LT8300
 power supplies
 but I thought I would query the group.

 Any thoughts on what would be your preferences?

 Thanks,

 Randy Evans

 On Mon, Aug 4, 2014 at 8:33 AM, Randy Evans randyevans2...@gmail.com
 wrote:

  I am looking at modifying my (defective) HP419A and Fluke 845A Null
 meters using the LTC2054 zero drift op amp.  I am planning on using
 a single 4.2 V Lithium Ion battery to power them (no AC input
 required and may not include, TBD).  The LTC2054 has a very low bias
 current of typically 1pA at room temp and the bias plots vs. temp
 show no appreciable increase until about 50C.  Conceptually, it
 looks pretty straight forward and, based on my Fluke 887A
 modifications, likely will be very stable.

 Since this is a very astute group, does anyone have any comments on
 the feasibility of this modification before I get too involved?

 Regards,

 Randy Evans



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[volt-nuts] Eppley standard cell catalog ?

[Pete Lancashire]

Looking for spec's on model 705489

-pete
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[volt-nuts] New (to me) Fluke 3330B

[Pete Lancashire]

Last Friday picked up a Fluke 3330B with manual for $20. Cal expired late
2012.

Anything to look out for when I get a chance to plug it in ?

-pete
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Re: [volt-nuts] New (to me) Fluke 3330B

[Pete Lancashire]

Hi David,

It was at a Ham Radio swap meet. Friday was setup day and for a change I
decided to have a table to see if I could get some junk to end up in
someone elses basement.

Seller didn't know what she had, everything on the table was $30-50, the
Fluke was $40, offered her $20 not expecting to get it, but she said sure.
Was the only thing TM she had.

My get a chance to plug it in this weekend, hopefully the company had it
just considered it not worth getting the cal redone.

-pete


On Thu, Jun 12, 2014 at 11:05 AM, David C. Partridge 
david.partri...@perdrix.co.uk wrote:

 Nice find Peter, I've been looking for a DC calibrator for ages w/o luck.
 Where did you find it?

 Regards,
 David Partridge
 -Original Message-
 From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On
 Behalf Of Pete Lancashire
 Sent: 12 June 2014 16:50
 To: Discussion of precise voltage measurement
 Subject: [volt-nuts] New (to me) Fluke 3330B

 Last Friday picked up a Fluke 3330B with manual for $20. Cal expired late
 2012.

 Anything to look out for when I get a chance to plug it in ?

 -pete
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Re: [volt-nuts] Another LED display wanted...

[Pete Lancashire]

Wow that's a rare one

Could just come up with the NSN 5962-01-175-1632

Long shot, do a looking for on the Seattle Craigslist, long shot but its
free.

-pete




On Tue, Jun 3, 2014 at 1:13 PM, Mark Sims hol...@hotmail.com wrote:

 I am looking for some (well at least one) DL02614 dual character 14
 segment common cathode LED display modules.  These were used in the Fluke
 5450A resistance calibrator.  They were made by Litronix and maybe Siemens.
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[volt-nuts] current-nut question .. total waste of ones time type question

[Pete Lancashire]

Next spring I'm going be rewiring my house. And for 'fun' I want to drop a
couple current sensors on the input side of the main panel.

Being a beginner 'nut', I'm looking for more accuracy then needed.

Voltage, Frequency, waveform will be taken care of later, but accurate
current has be a bit flustered.

I've been reading up on CT's Iron core and Ferrite, and on Rogowski coils.
And the many new IC's on the market that take care of a lot of things.

Has someone done this before ? And if so any experiences to share ?

-pete
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Re: [volt-nuts] current-nut question .. total waste of ones time type question

[Pete Lancashire]

Getting 2 % is pretty easy, many commercial CT's at 0.3% at the
transformer, resistance of the wire from the CT to the load (burden in the
electrical world), and all the things that effect voltage measurements come
into play. A well designed setup can get to 0.5%.

Thanks to surplus a classic 5A CT can be found for a few $'s. More modern
instrument grade CTs are expensive unless you can grab one off the usual
auction places.

A classic 100A or 200A:5A is a good 4-5 square and can be as much as
2-3 thick.

Today you don't need the 5 Amps, heck 10-50 mA is good enough, so the size
can be smaller.

I've been trying to shoot for say 0.1% to 0.2%. Again for 'fun'.

Where some more fun comes in is when you get below 10%, that would be
10Amps using a 100A CT. The industry specs stop at 10%. A 0.3% transformer
is only 0.3% at full rating (and above).

Was just looking to see if anyone has come up with something new / low cost
/ etc.







On Tue, Apr 29, 2014 at 12:06 PM, Brent Gordon volt-n...@adobe-labs.comwrote:

 Years ago I installed a TED-1000 (now obsolete) system from http://www.
 theenergydetective.com/.  Their software is terrible but the system
 works.  This system uses two current transformers and a single voltage
 measurement system that all go inside your circuit breaker box.  I don't
 recall the sampling rate (1 KHz maybe).  The instantaneous voltage and
 current measurements are multiplied, summed, and transmitted once per
 second.  The data is transmitted to a receiver using the house wiring
 (similar to X-10).  People have hacked the system to use their own receiver.

 I haven't directly measured accuracy; monthly totals are usually about 5%
 low when compared to my electric bill.  The software compensates for
 missing readings.  Resolution seems to be around 10 watts.

 Brent


 On 4/29/2014 11:25 AM, Pete Lancashire wrote:

 Next spring I'm going be rewiring my house. And for 'fun' I want to drop a
 couple current sensors on the input side of the main panel.

 Being a beginner 'nut', I'm looking for more accuracy then needed.

 Voltage, Frequency, waveform will be taken care of later, but accurate
 current has be a bit flustered.

 I've been reading up on CT's Iron core and Ferrite, and on Rogowski coils.
 And the many new IC's on the market that take care of a lot of things.

 Has someone done this before ? And if so any experiences to share ?

 -pete

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Re: [volt-nuts] Newbie here...

[Pete Lancashire]

Again just my few cents

 1 KV on the classics

Be very very careful. I was not uncommon for both of these guys to arc
over. If you do work with voltages in that space, consider a divider probe.

If you do keep playing over about 4 digits at some point you going to need
to decided that your absolute measurements are not  important or get
something like the 3456A calibrated, or the calibrator you have. I've had
good luck with one of the
few meteorology labs where I live having things calibrated for very little
as long as I don't want that little sticker.

Once they found out I had a just acquired set of LN 4000s that I wanted to
cal, they even let me do it myself.

For a few $'s there is a small one man company in Washington state that
sells a nicely done set of voltage sources.
http://www.voltagestandard.com/If you add up the parts cost, etc. they
are a bargain and well built (not a
customer but would be if didn't have the stuff I have).

-pete

There is a H-F about 1 mile from where I live. One day there were about 20
of the Red DMM in the dumpster, I could not resist. Fixed all except 2 put
2 in the truck and gave the rest away. 90% assembly issues.










On Sun, Feb 23, 2014 at 10:21 AM, Bob Albert bob91...@yahoo.com wrote:

 Well all comments are appreciated and well noted.  The 3456A is indeed a
 Pandora's box and is, as suggested, on the back burner for now.


 As for the Dana, I have tried all the above.  I replaced one IC that
 seemed to be the root of the trouble, to no avail.  The unit is very
 clean.  I spray cooled it when it did its trouble thing and it came back to
 operation but I haven't been able to find the offending component or solder
 joint.  Power supply seems good throughout.


 I paid so little for this, and I have so many other units, that I am loath
 to spend money on a diagram, especially when it is no guarantee of giving
 me the needed information.  Plus, the 300-page HP manual is free for
 download, so it feels like the tail is wagging the dog here.

 I will pay attention to the KO4BB site for when the HP manual will appear.

 But if I need to measure something, I certainly have the tools to do it.
 If the voltage is above 1 kV I have my Simpson 260 and Triplett 630-NA for
 that.  And I am ashamed to admit, a couple Radio Schlock VOMs.  The whole
 thing here is that I enjoy playing with accurate stuff even though I have
 no legitimate use for 6-digit voltage measurements.

 One thing about the HP that appeals is the accurate Ohmmeter.  I have a GR
 1658 bridge that is very accurate but it doesn't measure at DC, so is
 cumbersome for inductors, etc.

 And of course the delightful little toy, the Harbor Freight DVM, is a
 bargain that can't be approached by 'normal' units.  I have several of them
 and, within their limitations, they are great units.  There is a calibrate
 pot inside that takes care of any ordinary reading errors.  And if I blow
 it up, I pick up another without that dreaded feeling of having broken
 something valuable.

 Bob




 On Sunday, February 23, 2014 3:55 AM, Artek Manuals
 manu...@artekmanuals.com wrote:

 Bob et all

 1) We have a 1st class scan of the R-D 4200, manual with complete
 schematics available at a modest price
 2) We have a VERY NICE scan  (NOT a retread of the poor quality of
 Agilent scan) 600dpi scans of the schematics full size up to 27x 11
 unpieced, again at a very modest price
 3) I am sorry but we dont have manuals for the EI or Valhalla unit at
 the moment but I have added them to my watch for these list

 I have been following your saga on the 3456A repair on the Agilent forum
 and don't have much to add except to say this is not a trivial unit to
 troubleshoot because of the overly (IMO) complex nature of the beast .
 To paraphrase the old nursery rhyme, When they are good they are very
 very good but when they are bad they are horrid. I'd probably put that
 one on the back burner till you get more time , patience and experience.
 Then sit down and a read the theory of operation section of the manual
 till you can recite the whole thing by heart..THEN go digging into
 boards. With a unit this complex there are scores of feedback and
 reference check loops that it is often difficult to ascertain when
 troubleshooting  what is a  root cause and what is an effect of some
 other defect elsewhere in the circuit

 ON the erratic Racal unit, by comparison this is an easier unit to
 repair with a fairly clean layout of the main board. I would start by
 carefully unplugging and reseating all cable connectors and the Data I/O
 board, Display board and power supply diode board. next once the unit
 begins its erratic behavior after warm up, look at ( with a scope ) the
 AC ripple  on the DC +5V and +20V supply buses . Most likely suspects
 with any unit more than 25 years old ( aren't they all?) are the
 Electrolytic and Tantalum capacitors followed by solder joints that just
 need to be re-flowed. Given the lower complexity of the Dana 

Re: [volt-nuts] Newbie here...

[Pete Lancashire]

My take

HP 3456A - Great meter. Manuals on the web. Has at least one HP custom
device that is a problem,  other then salvaging from anohter 3456A is
unobtanium. The most complex of your collection.

Valhalla 4440. Other then for the fun of fixing stuff not worth anything.

Racal Dana 4200 Don't know it

EI 3000. I don't have a 3000 but do have a lower cost variant. At least to
me a collectors item. You say pretty close, pretty close to what ?  I
believe it was EI that originated feedback in the Zener loop, finally
getting rid of the chopper. If anything the reference by now should have
settled down :-).

Depending on your experience in repairing TM, I'd use the Valhalla as a
way to get some. Then get a manual for the 4200 and repair it. Finally dive
into the 3456A.

Love to see some inside pictures of the EI.

-pete




On Sat, Feb 22, 2014 at 5:35 PM, Bob Albert bob91...@yahoo.com wrote:

 I am the owner of a few fairly accurate and/or precise voltmeters and
 would like some information if it's available.


 First, my Electro Instruments model 3000 5-digit antique with Nixie tube
 readout, and the accessory AC converter.  It hasn't been calibrated in
 decades but seems pretty close.  I have no manual.


 Second is the recently acquired, not working HP 3456A.  Struggling with
 that repair.

 Third is the Valhalla 4440.  I have most of a manual but it differs
 somewhat from mine.  Mine has an issue on one range of volts.

 Fourth is the Racal-Dana 4200.  This works fine but after it warms up for
 a half hour starts to get erratic.

 Fifth is a Calibration Standards model DC-110A.  No manual.  It has some
 trouble on range overlap.

 Can anyone help me with any of these units?  Documentation, reputation,
 etc.  Photographs supplied if needed.

 Bob
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Re: [volt-nuts] Who bought a DT72A Dekatran Decade Transformer?

[Pete Lancashire]

Just my 37 cents. One has to be careful. Ratio transformers can be easily
damaged. Unless yo find one cheap enough to gamble make sure you have a ROR

-pete




On Mon, Jan 27, 2014 at 6:00 AM, Jan Fredriksson j...@41hz.com wrote:

 Any voltnut bought one yesterday from Ebay?
 Looks like a nice box and a very decent price.
 Tell us more!

 I'd like a pair as volume control for my stereo :-)
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[volt-nuts] Fluke Diff's

[Pete Lancashire]

I'm working on a list/table of the Fluke 800/900 solid state
differentials.

Will be putting on a public web page when close to being
done.

If anyone can help fill in the 'blanks' or add comments I would
greatly appreciate it.

Thanks

-pete

Data so far

871A
   DC 3+dial

   Have seen with 801 10KV divider 1K:1 10K:1

883A
   DC 4+dial

883AB
   AC/DC  4+dial

   http://helmut-singer.de/pdf/fluke883ab.pdf

   Basic dc voltage accuracy is 0.01% of indicated value + 5 µV. Resolution
is 1 µV.

885A

885AB
   DC4+dial

   DC Differential Voltmeter achieved an absolute accuracy of 25 parts per
million of
   input +1 ppm of range +5 microvolts from 0 to 1100 VDC.

887A
  DC/AC  4+dial

  http://www.teknetelectronics.com/DataSheet/Fluke/Fluke_887A41504.pdf

  http://bama.edebris.com/download/fluke/887a/FLUKE_887A.pdf

  Basic DC voltage accuracy is 0.005% of indicated value. Resolution is 1
µV.

887AB
  DC/AC  4+dial

  http://assets.fluke.com/manuals/887A_887imeng0200.pdf

  Artek

891A
   DC 3+dial

893A
   AC/DC  3+dial  01-Battery 02-Recorder two diff case styles

   http://assets.fluke.com/manuals/893A_AR_imeng.pdf

   AC and DC with 1uV Resolution, accuracy is +/-0.01% (DC) and +/-0.05%
(DC), 50Hz to 10kHz.

   Artek

   893AP ?

   893AR 893A in a 'flat' 2 RU ? Rack

895A
   DC 4+dial

931A
   RMS3+dial

   Opt 01 Battery Pack
   0pt 02 Probe Input
   Opt 03 01+02

   http://www.teknetelectronics.com/DataSheet/FLUKE/FLUKE_931B114917.pdf


http://www.artisantg.com/info/PDF__466C756B655F393331425F446174617368656574.pdf


335D DC Voltage Standard Diff Voltmeter

   http://assets.fluke.com/manuals/335dimeng0100.pdf
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Re: [volt-nuts] Fluke 343A part

[Pete Lancashire]

I've used Talon as well, their prices are usually only affordable by
taxpayers via their respective governments but like this one they have
surprised me in the past. One time they sent me the wrong part and
they sent me the replacement and asked at
my convience to send the other one back



On Wed, Nov 7, 2012 at 11:36 AM, Dick richiem5...@gmail.com wrote:
 Thanks John -- You are the second one to suggest them. Talon is the deal for 
 sure. I ordered two of these parts. Fluke used them in a lot of gear.

 Have any volt-nuts modified the chopper system of the 343A to reduce parts 
 count and improve stability? Seems like a good place for an LT1150, OPA627 or 
 some such to improve overall performance

 Dick Moore


 On Nov 7, 2012, at 4:00 AM, volt-nuts-requ...@febo.com wrote:

 Message: 1
 Date: Tue, 6 Nov 2012 14:10:16 +
 From: John Lofgren jlofg...@lsr.com
 To: Discussion of precise voltage measurement volt-nuts@febo.com
 Subject: Re: [volt-nuts] Fluke 343A part
 Message-ID:
   5544e52d608067489823b4aed0bb6b570b0b7...@exchange2010.lsr.local
 Content-Type: text/plain; charset=us-ascii

 Talon Electronics shows a Fluke FP226043 as the replacement for the MEM556C. 
  They have 48 in stock at $5.12 with no minimum order.
 http://www.talonix.com/shop/item.aspx?itemid=3978

 -John


 -Original Message-
 From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On 
 Behalf Of Dick
 Sent: Tuesday, November 06, 2012 1:06 AM
 To: volt-nuts@febo.com
 Subject: [volt-nuts] Fluke 343A part

 I picked up a fairly new Fluke 343A and it appears that Q39, MEM556C p-chan. 
 enhancement-mode MOS-FET is shorted. This part seems to be unobtanium unless 
 you are named Romney, Gates, or Walton. Any suggestions on a replacement or 
 an alternative method? This part is the input signal chopper transistor, 
 driven by a multivibrator.


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Re: [volt-nuts] ESI 2100

[Pete Lancashire]

Mark has it pretty much, toss in the keyboard switches go bad as well,
and even the assembly quality was poor.

The product was quite the low point for ESI and basically the end of
their instrument line. A friend
worked at ESI on their laser trimmer products and did not have many
good things to say about
their design follow through.

-pete

On Mon, Oct 29, 2012 at 11:44 PM, Mark Sims hol...@hotmail.com wrote:

 A common fault with these is the Mostek CPU/peripheral chips on the 
 motherboard.  The pins corrode away.
 Another common fault is with the video monitor.  I had one where the socket 
 on the CRT was bad... intermittent connection to the filament.  Another blew 
 a couple of transistors.  Also the pots needed to be cleaned.
 ManualsPlus.com has the service manual...  $70
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