Re: [volt-nuts] HP 735A DC Transfer Standard

[R.Phillips]

Hi Bill
Well I suppose I should have guessed it - Fluke are probably the # 1 when it 
comes to DC 'Standards'  I had never encountered an HP-735 before and this 
one is in overall good condition - I will complete the restoration and keep 
it as a 'collectors item (its not too big!) As for the fluke range, I have 
two 731B's and better, a Fluke 732A which has been running non-stop for more 
than a year - it now reads the same on my HP 3458A , which is still in 
calibration. I agree that the Fluke 731B is a good standard for its size, 
pity about the 'poor' battery back-up circuitry, and the NI-CADs which have 
damaged so many. The other shortcoming was the rotary switch - it would have 
been better with a set of terminals for each range.

Regards
Roy


From: wb6bnq
selection
-Original Message- 
Sent: Monday, May 18, 2015 10:29 PM

To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] HP 735A DC Transfer Standard

Hi Roy,

I hate to tell you but the hp-735 does not compare to the Fluke 731.
The hp-735 had a drift that was constant.  This information came from a
friend of mine that was responsible for the US Navy's Primary DC voltage
standard at their Primary Lab in San Diego, CA in the 1970's.  The
actual drift rate I do not recall anymore, but it was significantly
higher than the any drift in the Fluke.

BillWB6BNQ

R.Phillips wrote:




-Original Message- From: gilb...@nickgilbert.org
Sent: Sunday, May 17, 2015 4:13 AM
To: volt-nuts@febo.com
Subject: [volt-nuts] HP 735A DC Transfer Standard

Recently acquired a HP 735A DC Transfer Standard. Replaced some caps, but 
its otherwise clean and has since been powered. Read a post recently about 
a 735A oven failure that included a teardown that revealed why HP states 
the oven/ref assembly a non-serviceable part. The failure in this person's 
device was the heater, specifically the thermistor.


Anyone on this board have a 735A in use? Do you keep it powered 24/7 or 
as-needed? Any failures/repairs/mods?


Best
Nick
__

Hi Nick
I also very recently  acquired a HP 735A DC Transfer Standard. Mine has a 
Power Transformer with the centre tap 'open circuit' - this I guess was 
the result of a failure in the pre-regulator circuit which in turn caused 
a resistor to 'burn-out'. I have 'hooked-up' external positive and 
negative rails and the unit works, including the oven !  So, I will 
rebuild this to the later and I think final specification - which 
eliminates the 'pre-regulator' circuit. Otherwise the unit is in excellent 
condition, in keeping with HP of that period, and probably superior to the 
Fluke 731B. I gather that these are quite rare items now. Let us know how 
you get on with the 'project'

Regards
Roy Phillips.


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Re: [volt-nuts] HP 735A DC Transfer Standard

[R.Phillips]

-Original Message- 
From: gilb...@nickgilbert.org

Sent: Sunday, May 17, 2015 4:13 AM
To: volt-nuts@febo.com
Subject: [volt-nuts] HP 735A DC Transfer Standard

Recently acquired a HP 735A DC Transfer Standard. Replaced some caps, but 
its otherwise clean and has since been powered. Read a post recently about a 
735A oven failure that included a teardown that revealed why HP states the 
oven/ref assembly a non-serviceable part. The failure in this person's 
device was the heater, specifically the thermistor.


Anyone on this board have a 735A in use? Do you keep it powered 24/7 or 
as-needed? Any failures/repairs/mods?


Best
Nick
__

Hi Nick
I also very recently  acquired a HP 735A DC Transfer Standard. Mine has a 
Power Transformer with the centre tap 'open circuit' - this I guess was the 
result of a failure in the pre-regulator circuit which in turn caused a 
resistor to 'burn-out'. I have 'hooked-up' external positive and negative 
rails and the unit works, including the oven !  So, I will rebuild this to 
the later and I think final specification - which eliminates the 
'pre-regulator' circuit. Otherwise the unit is in excellent condition, in 
keeping with HP of that period, and probably superior to the Fluke 731B. I 
gather that these are quite rare items now. Let us know how you get on with 
the 'project'

Regards
Roy Phillips.


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Re: [volt-nuts] Calibration of voltage standards

[R.Phillips]

I think I was the Keithley 155 owner that ask the question.  Since then I 
have added an HP3245A to my equipment which I have set to 1.00 V DC, 
read by my "in calibration" HP3458A, and then compared by the Keithley 155 
against my Fluke 732A's 1.000 v output - this is showing a steady -1 uV on 
the 155's , 1 or 3uV range. I have replaced the batteries in the 155 with 9 
volt (6LF22/MB1604) batteries, works fine.   I also have a Fluke 845AB which 
I would suggest is less stable. Best regards


Roy Phillips.


-Original Message- 
From: acb...@gmx.de

Sent: Wednesday, February 11, 2015 10:00 AM
To: volt-nuts@febo.com
Subject: Re: [volt-nuts] Calibration of voltage standards

for those interested, and for simplicity, wanted to add this from David 
which was in voltnuts in 2012.




From: Charles P. Steinmetz 
To: Discussion of precise voltage measurement 
Sent: Saturday, 15 December 2012, 10:28
Subject: Re: [volt-nuts] Fluke 335A versus HP 740B

David wrote:


I have a Keithley 155 Null Detector how does that rate?


The three usual suspects are the Fluke 845AB, the HP 419A, and Keithley 155. 
I have one of each, and they are all good meters.  The received wisdom is 
that the Fluke is the one to have.  However, in my view, the Keithley is the 
best of the bunch.  It is a bonus if you find one with the rare 1554 AC 
power module (the 1554 mounts to the rear panel and allows AC operation --  
otherwise, it is battery-only).


The main problem today with the HP is that it uses impossible-to-find 
batteries.  Not only are the original batteries unobtainable, I have yet to 
find a satisfactory replacement strategy.  It also does not have a +/- 1 uV 
range, although I do not count that as a major fault since thermocouple 
noise in the measurement setup frequently prevents taking full advantage of 
the 1 uV range.


The Fluke's batteries (sub-C NiCd cells) are readily replaced (though not 
inexpensively, if you get the best cells).  Keithley used four, # 246 9 V 
carbon cells, which can easily be replaced with common 9 V alkalines or 9 V 
primary lithium cells that simply plug into the existing connectors.


The HP and Fluke both use photocell choppers.  Fluke published pre-release 
information indicating that they had designed a FET chopper for later 
production, but I have never seen an 845 with a FET chopper or a schematic 
of the FET chopper.  (Does anyone here have either?)  The Keithley was 
designed with a MOSFET chopper from the start.


Not only is the Keithley the most modern design and the most likely to 
remain reliable, it also performs the best in my lab.  I have had fewer 
ground loop and shielding problems with it than with the Fluke, and it has 
less noise and less drift.  It is not enough better that most people should 
sell their Fluke to get a Keithley just for the performance difference 
(reliability may be another story), but -- IME -- it does perform better.


They are all good meters, but IMO the Keithley is the best of the three.  If 
I had only one, that is the one I'd want.


Best regards,

Charles



Gesendet: Mittwoch, 11. Februar 2015 um 08:55 Uhr
Von: wb6bnq 
An: "Discussion of precise voltage measurement" 
Betreff: Re: [volt-nuts] Calibration of voltage standards

To amplify Chuck's point,

The only meter worth considering, if you are going to get one, is the
FLUKE 845.  Preferably, the battery operated version which has a higher
isolation leakage resistance.  However, the 110
volt rack mount model would do just as equally.

BillWB6BNQ


Chuck Harris wrote:

> To do a comparison of the sort you are asking about, the
> sensitivity of the null meter is much more important than
> its ultimate accuracy.
>
> So, neither of your meters is really the right meter to
> use for this task.  What you want is called a null meter,
> and is generally sensitive to the microvolt region.
>
> -Chuck Harris
>
> Ken Peek wrote:
>
>> Hi Group,
>>
>> I have heard of a few different ways to measure one 10V voltage 
>> standard

>> against another 10V voltage standard.
>>
>> Assume we have two 10V voltage standards.  One is calibrated, the other
>> not only needs to be calibrated, but probably adjusted.  For the sake 
>> of

>> simplicity, let's say the two standards are Fluke 732B's.
>>
>> I *think* the best way is to connect the two units' (-) terminals
>> together, then connect a calibrated meter in between the (+) terminals,
>> and measure the difference.  I have also heard that to remove thermal
>> EMFs, you should use a low-thermal-EMF DPDT switch or a low-thermal-EMF
>> relay to reverse the connections on the DMM, so you can take the 
>> reading

>> forward and reversed, then split the difference.  There is the
>> possibility to introduce thermal-EMF errors from the switch/relay as
>> well, so I'm wondering if this is a good idea.  This sort of makes 
>> sense
>> to me, but I'm not a metrologist, so I would like to hear what others 
>> in

>> this group t

Re: [volt-nuts] Fluke 732A themistor reading

[R.Phillips]

Randy
I have had mine working non-stop for almost 1 year - its current reading is 
4.51902 K ohms, it never deviates more than 0.150 ohms.

Roy


-Original Message- 
From: Randy Evans

Sent: Sunday, August 17, 2014 8:51 PM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Fluke 732A themistor reading

Todd and Bill,

Thanks for the input.  The 3.6 K thermistor reading seems viable and i will
pursue it further.

I may have over committed myself to modifying the HP-419A, the Fluke 845A,
buying the 3458A and looking at buying a Fluke 732A.

So much to do and so little time.

Thanks again,

Randy


On Sun, Aug 17, 2014 at 11:48 AM, Bill Gold  wrote:


Randy:

I have 6 ea Fluke 732A instruments.  The results of being an over the
edge and deeply obsessed "Volt Nut", they just kept adding (reproducing?)
over the years.  My readings for the themistors range from 3.407K OHMS to
4.514K OHMS and all work just fine.  3.6K OHMS would seem just fine to me.
It really depends upon the final inside temp of the oven assembly.  The 
one
with 3.407K OHMS measures around 47.5 degrees C while the others are 
around

45 C.  It is the stability of this reading over time that is very
important.
Fluke says that it could change as much as 10 ohms per month but mine are
rock solid for years and years.

Bill

- Original Message -
From: "Randy Evans" 
To: 
Sent: Sunday, August 17, 2014 11:08 AM
Subject: [volt-nuts] Fluke 732A themistor reading


> Can anyone tell me what value to expect for a Fluke 732A thermistor
> reading?  I am looking to get a used 732A and one of the things I was
told
> to look for is to measure the thermistor reading after the unit has
heated
> up for at least an hour.  I saw in one of the posts that a "typical"
> reading was 4950 ohms.  One vendor I asked said he measured about 3600
ohms
> after a two hour warmup. I was concerned that this is too low.  What do
you
> guys think?
>
> Thanks,
>
> Randy
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Re: [volt-nuts] RE "new" 3458A

[R.Phillips]

Randy
I would guess that your display is almost certainly 'on its way out'.  I had 
a new display fitted to my 3458A earlier this year and the difference is 
astounding. The display is of the vacuum-fluorescent type, and they will 
deteriorate over time, especially if your instrument was used in a Lab. for 
24/7 - and many had been. As I live in the UK, I am not able to give you a 
price as it was a 'package deal' - but I'm sure you get better deal in the 
US.

Roy


-Original Message- 
From: Randy Evans

Sent: Sunday, August 17, 2014 6:36 AM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] RE "new" 3458A

Interesting note.  After the room cooled down from about 79F to 73F, and
another ACAL, the meter now reads +000.00035 mVDC, a more reasonable value,
although it does bounce around a couple of tenths of a uV.

Maybe that is OK?  If so, then the only issue would seem to be the  display
has some faint pixels, which a new display should fix.

Randy


On Sat, Aug 16, 2014 at 9:59 PM, Randy Evans 
wrote:



The unit seems to be working so far except for one issue.  After doing an
ACAL, and making sure the Auto Zero is ON,  I short the input leads with a
copper wire shunt across the inputs and the reading is approximately
 -000.0023 mVDC.  That seems rather high.  I would expect the unit to 
short

the input leads internally and force a zero reading during the ACAL.
Anyone have any comments on this reading?

Thanks,

Randy


On Sat, Aug 16, 2014 at 3:37 PM, Richard Moore 
wrote:


Hi Randy -- sounds like your unit is in cal, based on your measurements
of DCV and precision 10k resistor.

Using autocal all is recommended before doing precision measurements, and
I do that if it's been more than a day or two since last use. The autocal
uses the internal Vref and an internal 10K resistor to do cal on 
everything
else, so that tells you what the basic cal procedure is. I just got my 
3458

back from Loveland, and that's what they did for me -- warmed it up, then
ran autocal, then measured everything against a Fluke 5700, aided by an 
HP

3325, and another 3458.

It has been 5 years since I replaced the display board (no "exchange"
deal was available then AFAIK, so I don't know what's changed) and also 
the

NVRAM board, which was dead, with one with the Snap-cap RAM chips. I did
those replacements, then sent it home for cal, which was complete, since
all the RAM was new. Now after 5 years, the unit passed all incoming
performance tests and was sent back to me without a cal process of any
kind. This tells me that an old, well-aged Vref module is a good thing. 
The

10VDC test had changed by a bit under 5ppm, or roughly 1ppm/year.

They have a cal deal -- use code 1.090 -- press them for it -- and that
saved me 30% off the normal price. I think this deal lasts until
mid-September, so my recent "cal" ended up at just under $400 including
shipping. I'm not sure the deal is available on new or first-time cals; 
my

unit was in their data bank.

But this is a long way of saying I don't think you need to send it for
cal -- just push Auto Cal and Enter and wait about 10 minutes and you
should be good to go.
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Re: [volt-nuts] HP-419 and Fluke 845 Modifications

[R.Phillips]

Hi Frank
I have read your comments on the make-up and performance of the 845, so how 
do you compare the Keithley 155 which I think was a later design ?

Roy


-Original Message- 
From: Frank Stellmach

Sent: Tuesday, August 05, 2014 10:33 PM
To: volt-nuts@febo.com
Subject: [volt-nuts] HP-419 and Fluke 845 Modifications

Hi Randy,
to modify the 845 with a modern chopper OpAmp is a great idea, and will
for sure improve its performance, rather than degrade it.

Fluke never specified the leakage currents of its chopAmps, neither in
the 845, nor in the 332 / 335 or 334 MOSFET Chopamps..

The real replacement input resistance was never specified, only the
isolation resistance, but not described, against which potential, or in
which arrangement. Compare that to FET and Chopper OpAmp specifications!

And the optical chopper of the 845 goes into bipolar transistors, not
even FETs were used!
Therefore, the resulting input currents, caused by imperfections of the
optical chopper, may also be in the high pAs, or nA, nobody ever has
measured that, but will also give arithmetical 10E13 Ohm at voltage
differences below µV level...

The great thing about the 845 is its 1kV isolation of input to monitor
output, but this will not be changed, if you replace the bipolar /
optical chopper amplifier stuff..

I think, nobody dared to modify the 845, or questioned it, because this
instrument is a "myth", indicated by the price, you still encounter on
ebay...


For the Hp419, everything i described is  the same here, the difference
of this circuitry is the lack of the isolation transformers only.

Therefore, go ahead, and maybe - please specify the bias currents before
/ after modification.

Frank
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Re: [volt-nuts] Buying HP-3458A

[R.Phillips]

Randy
I'm already forgetting some of the facts that made up the price that I paid 
for the repair and re-cal. for my 3458A, as I have been involved in a number 
of other restoration/repairs, but it was remarkably similar in £ sterling, 
against your US $ price - so I guess it would seem to be a fixed charge ? My 
instrument failed when the 'classic' RAM/ROM 's ran out of battery support 
and further, they found another section which had gone bad. There's nothing 
to give your more confidence than the Agilent Calibration Certificate that 
comes with the package,as this is probably the prime instrument in the 
collection of we lucky owners, so it has to be good.  As I have stated in a 
previous exchange, the 'new' processor/ROM/RAM board is now fitted with 
sockets, and the devices that were formerly fitted, have been replaced with 
the new type that only connect the battery support power when they are 
plugged in to their sockets.

Roy


-Original Message- 
From: Randy Evans

Sent: Sunday, July 06, 2014 6:44 PM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Buying HP-3458A

That e-mail I referenced is several years old.  i believe the current
repair price is just over $2800.

Randy


On Sat, Jul 5, 2014 at 10:49 PM, John Phillips 
wrote:


​They do really offer that service as​ long as you send them a complete
meter... No missing parts. Well they will take a few missing screws and
such. My experience with them is they charge the same no mater what need 
to
be fixed. Not sure what the price is, there prices are country dependent. 
I

thought it was a little more than $2200 last I checked.


On Sat, Jul 5, 2014 at 4:08 PM, Randy Evans 
wrote:

> I am in the market for a used HP-3458A and, in researching past
messages, I
> came across an interesting question:
>
> *Chris Erickson* ericksonc2 at comcast.net
> 
40febo.com?Subject=Re%3A%20%5Bvolt-nuts%5D%203458A%20questions&In-Reply-To=%3C001b01cc7960%24a15d2840%24e41778c0%24%40net%3E
> >
> *Thu Sep 22 19:48:41 UTC 2011*
>
> If Agilent will fix everything, bring it up to specs, and calibrate it 
> no

>
> matter what's wrong with it for $2200, then why would I spend $5000-6000
or
>
> more for one that is in good shape - even if calibrated? Just grab the
> first
>
> bargain that comes along for $1500-3000, send it straight to Agilent and
be
>
> money ahead. Seems the better course of action to me if that price is
>
> accurate - do they really offer this service?
>
>
>
>
> I could not find an answer to this question but it does beg the 
> question.

>  Does nayone have an answer as to why not buy the cheapest unit and send
it
> in for repair?
>
>
> Thanks,
>
>
> Randy Evans
> ___
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--
John Phillips
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Re: [volt-nuts] Buying HP-3458A

[R.Phillips]

I note with interest your considerations with restoring the 3458A.  I have 
recently had my 3458A restored (April-last) to fine working order, and 
calibrated by the Agilent Service Department here in the UK. It will cost 
what is required after their inspection - this inspection is a 'free' 
service which gives you a full appraisal, and a price for what has to be 
done to restore the instrument to 100% working order followed by 
re-calibration. If the cost is unacceptable, you can request the return your 
instrument back with a report on what would be required. The reality is that 
many owners have tried to make a 'cheaper fix' and finished up with an 
unsatisfactory result, as Agilent are not try to calibrate a faulty unit. 
Over the period of the models production, a number of changes have been 
introduced, I now have the latest type of processor/RAM/ROM board which is 
much improved. Considering the cost of a new instrument, I would suggest 
this is the best solution. I found the staff here in the UK to be very 
helpful and willing to discuss any technical matter.

Roy Phillips.

-Original Message- 
From: acb...@gmx.de

Sent: Sunday, July 06, 2014 9:45 AM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Buying HP-3458A

I recently bought a non-working 3458, so faced the same problem. it was a 
relatively old unit, and I asked agilent germany (where I live) for a 
standard repair quote. they answered they would not give a fix price, they 
would evaluate the costs once received. it may have been linked to the age 
of the unit (SN arround 3k). I would therefore think that in other places in 
europe the response may be similar. it may be differnt in the US.
I determined the A/D board was faulty, and I did a check on that, it would 
have been considerably cheaper to just replace this. so for me, since I am 
also calibrating the unit myself, it would anyway have been a bad deal. 
fortunatelly I could fix the a/d myself, so could save this as well. given 
my buy price and list price for the a/d baord, it would otherwise probably 
have been a no so good deal. so I would say there is really some risk 
involved buying an old gear. also, keep in mind, boards may work but still 
be out of spec. so you may need a new A/D board just to figure out later 
that the ac board is not within specs either.
key I guess is that the error messages give you a reasonable understanding 
whats wrong. find out the cost of this board, and if thats ok in total it 
may make sense, but you still have quite a risk as the other items may have 
an issue as well. if a unit is completely dead, I would probably not buy. as 
far as i know you cannot buy a new PU board allone, you need to send it in 
to repair (thats what agilent germany states on ther parts list side), and 
then it may be very costly if other stuff it broken too.




Gesendet: Sonntag, 06. Juli 2014 um 07:03 Uhr
Von: "Dr. David Kirkby (Kirkby Microwave Ltd)" 


An: "Discussion of precise voltage measurement" 
Betreff: Re: [volt-nuts] Buying HP-3458A

On 6 Jul 2014 07:12, "John Phillips"  wrote:
>
> ​They do really offer that service as​ long as you send them a complete
> meter... No missing parts. Well they will take a few missing screws and
> such.

There is also the possibility someone has tried repairing it, but done so
badly.

I assume that there has been some design changes over the years, so not 
all

boards are identical.  Agilent would probably decline to fix a unit made
from parts from a mixture of revisions.

Buying one and hoping to get it repaired for a fixed fee seems a bit risky
to me.

Dave

My experience with them is they charge the same no mater what need to
> be fixed. Not sure what the price is, there prices are country 
> dependent.

I
> thought it was a little more than $2200 last I checked.
>
>
> On Sat, Jul 5, 2014 at 4:08 PM, Randy Evans 
> wrote:
>
> > I am in the market for a used HP-3458A and, in researching past
messages, I
> > came across an interesting question:
> >
> > *Chris Erickson* ericksonc2 at comcast.net
> >  >
40febo.com?Subject=Re%3A%20%5Bvolt-nuts%5D%203458A%20questions&In-Reply-To=%3C001b01cc7960%24a15d2840%24e41778c0%24%40net%3E
> > >
> > *Thu Sep 22 19:48:41 UTC 2011*
> >
> > If Agilent will fix everything, bring it up to specs, and calibrate it
no
> >
> > matter what's wrong with it for $2200, then why would I spend
$5000-6000 or
> >
> > more for one that is in good shape - even if calibrated? Just grab the
> > first
> >
> > bargain that comes along for $1500-3000, send it straight to Agilent
and be
> >
> > money ahead. Seems the better course of action to me if that price is
> >
> > accurate - do they really offer this service?
> >
> >
> >
> >
> > I could not find an answer to this question but it does beg the
question.
> >  Does nayone have an answer as to why not buy the cheapest unit and
send it
> > in for repair?
> >
> >
> > Thanks,
> >
> >
> > Randy Evans
> > _

Re: [volt-nuts] A Fluke 732A: Return it or keep it?

[R.Phillips]

ltage adjustment alone. You already have stable outputs and 24 microvolts
high is very acceptable. My Datron 4910 (four output supply) has predictable
digital output level settings that doesn't have any luck involved so it is a
better candidate for resetting the standards than the Fluke 732A. I had
Fluke reset them last calibration because I had just repaired the Datron
4910 and my voltages were all over the place but stable.  Also I would
expect your Fluke 732A to about as temperature stable as my Datron 4910. In
my experience my 3458A needs to be at 23C to calibrate. Also it should have
the fan filter freshly cleaned and record the 3458A's internal temperature.
I have recorded (over several
days) each Datron 4910 output with my 3458A and a switch and can say that
the Datrons are temperature stable but not my 3458A.

Charlie

On 6/12/2014 7:54 AM, Bill Gold wrote:

Roy:

 I use a ( General Cement ) GC 8276 adjustment tool to make the
pot adjustments in the 732A.  I use the end that has the recessed metal

blade.

The pots are about 3.5 inches back from the front panel.  It sometimes
is very difficult to engage the tool slot in the pot.  It helps to
look through the front panel hole with a small flashlight and observe
the position of the slot in the pot ( i.e. 9, 10, 11 o'clock for
example ).  Then when you insert the adjustment tool you can get close
to the point when you can engage the adjustment pot.  Sometimes it
will seem impossible to engage the tool into the slot, but with
patience it can be done.  Once you do engage the pot do whatever
adjustment you want, don't pull the tool out, just leave the tool
engaged with the pot so that if you want to make another small change
you won't have to go through the same problem of trying again and again to

engage.

 I have found that turning the pots may cause a drift which will
show up days later due to the pot being "dirty" or whatever.  So what
I usually do is to turn the pot back and forth over several
revolutions so that I can "clean" the contact wiper.  I usually make
an initial adjustment and then turn the pot about 1/32 of a turn in
the opposite direction just to relieve any "stress" that might be
there and cause a small change in the output voltage.  I usually have very

good results with these methods.

 But I will agree with Joe that sometimes it is better just to
leave things alone and just use the known offset from 10 volts when
checking or doing cals.
Bill


- Original Message -
From: "Todd Micallef" 
To: "Discussion of precise voltage measurement" 
Sent: Thursday, June 12, 2014 7:20 AM
Subject: Re: [volt-nuts] A Fluke 732A: Return it or keep it?



Roy,

The 732A uses the 3059Y-1-101 type cermet pot for the 10V adjustment.
You can use a simple plastic tweaking tool for adjustment. I believe
you will need a fairly long tool. You can shine a light into one of
the other holes to see the orientation of the pot. However, many
people may prefer to

leave

the pot as is and just record the readings. It is going to drift
anyway

and

won't stay adjusted for long. The drift may worsen once the pot
position has changed too. I have adjusted mine, but only after the
broken pots were replaced.

Todd


On Thu, Jun 12, 2014 at 9:57 AM, R.Phillips 

wrote:

Hi Joe
Sorry if I am retracing steps, but I have recently had my 3458A
restored/recal'd  by Agilent - its good to have it back. I also have
a Fluke 732A which I can now check. Currently it is 10.24 volts,
I now feel confident to trim it to the 3458A. I have tried to see
the trimmers

in

each of the three holes - they appear to be some way within, and I
am wondering if you could confirm the type of pot. that is used and
just

how

long a trimming device is required. Is this a special tool only

available

from Fluke ?
Regards
Roy Phillips.


-Original Message- From: J. L. Trantham
Sent: Saturday, March 08, 2014 10:09 PM

To: 'Discussion of precise voltage measurement'
Subject: Re: [volt-nuts] A Fluke 732A: Return it or keep it?

Charles,

What size batteries did you use for your external pack and where are
you located?  In other words, how long can your external battery
pack

'survive'

keeping the 732A 'hot'?  Is the external pack recharged at Fluke or
does

it

have to make a round trip on the initial charge?  Once I am
convinced my unit is stable (which will probably be another six
months or so, after I get my 3458A's re-calibrated by Agilent), I
hope to be able to send it to

Fluke

for calibration.

Fluke made a transit case (732A-7002) and a Battery Charger and

Auxiliary

Battery Case (732A-7003).  However, I have never seen a picture of

either

of
these.  Does anyone have any information on these?

How did you make your case?  Did you include a charger?  Combination
of battery pack and shipping container or separate battery pack and

shipping

conta

Re: [volt-nuts] A Fluke 732A: Return it or keep it?

[R.Phillips]

Todd
Thank you - I'm sure you are right - leave alone - as my 24 micro V is very 
stable, and always come up following an auto-cal. on the 3458A The 1.0800 v 
reads 1.018006 , and the 1. v reads 1.10. I gather the latter two 
outputs are derived from the 10 volt source, so would be affected by any 
adjustment.

Roy


-Original Message- 
From: Todd Micallef

Sent: Thursday, June 12, 2014 3:20 PM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] A Fluke 732A: Return it or keep it?

Roy,

The 732A uses the 3059Y-1-101 type cermet pot for the 10V adjustment. You
can use a simple plastic tweaking tool for adjustment. I believe you will
need a fairly long tool. You can shine a light into one of the other holes
to see the orientation of the pot. However, many people may prefer to leave
the pot as is and just record the readings. It is going to drift anyway and
won't stay adjusted for long. The drift may worsen once the pot position
has changed too. I have adjusted mine, but only after the broken pots were
replaced.

Todd


On Thu, Jun 12, 2014 at 9:57 AM, R.Phillips  wrote:


Hi Joe
Sorry if I am retracing steps, but I have recently had my 3458A
restored/recal'd  by Agilent - its good to have it back. I also have a
Fluke 732A which I can now check. Currently it is 10.24 volts, I now
feel confident to trim it to the 3458A. I have tried to see the trimmers 
in

each of the three holes - they appear to be some way within, and I am
wondering if you could confirm the type of pot. that is used and just how
long a trimming device is required. Is this a special tool only available
from Fluke ?
Regards
Roy Phillips.


-Original Message- From: J. L. Trantham
Sent: Saturday, March 08, 2014 10:09 PM

To: 'Discussion of precise voltage measurement'
Subject: Re: [volt-nuts] A Fluke 732A: Return it or keep it?

Charles,

What size batteries did you use for your external pack and where are you
located?  In other words, how long can your external battery pack 
'survive'
keeping the 732A 'hot'?  Is the external pack recharged at Fluke or does 
it

have to make a round trip on the initial charge?  Once I am convinced my
unit is stable (which will probably be another six months or so, after I
get
my 3458A's re-calibrated by Agilent), I hope to be able to send it to 
Fluke

for calibration.

Fluke made a transit case (732A-7002) and a Battery Charger and Auxiliary
Battery Case (732A-7003).  However, I have never seen a picture of either
of
these.  Does anyone have any information on these?

How did you make your case?  Did you include a charger?  Combination of
battery pack and shipping container or separate battery pack and shipping
container?

I was thinking of building a case with built-in charger, fuse, and AC
connector and cord such that when the unit arrived at the CAL facility all
that would be needed would be to plug it in and allow the external battery
pack to recharge while the unit being calibrated was plugged in, recharge
the internal batteries, and calibrated.  Or does the 732A also charge the
external battery pack along with the internal batteries?

The connector you need (complete with female contacts) is a Hypertronics
P/N
D01PB306FSTAH and is in stock at Kensington Electronics at $8.96 each 
(plus

tax and shipping).  Only problem is their $50 minimum order.

The 'shell' only is P/N D01PB306NT and the female contact is P/N
YSK006-010ANH (three needed).

http://ecommerce.keiconn.com/hypertronics/D01PB306FSTAH

I ordered two of the connectors from Fluke using a P/N that one of the
Fluke
folks in their eCal facility gave me, noting that someone else had asked
the
same question a couple of weeks earlier, with Fluke Item# 2181497,
described
as '100-166, PLUG - MALE, HYPERTRONICS'.  They were $12.31 each (plus tax
and shipping) and arrived as the shell only, no contacts.

If Fluke solves their supply chain problem, I sure would like to get the
six
female contacts I need to make my connectors 'complete'.  When I got on 
the

phone with Fluke, I could never find anyone that had any knowledge about
this.  Is there anyone there I should ask for that might understand my
question?

I look forward to your posting the update from Fluke.

Thanks.

Joe


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Re: [volt-nuts] A Fluke 732A: Return it or keep it?

[R.Phillips]

Hi Joe
Sorry if I am retracing steps, but I have recently had my 3458A 
restored/recal'd  by Agilent - its good to have it back. I also have a Fluke 
732A which I can now check. Currently it is 10.24 volts, I now feel 
confident to trim it to the 3458A. I have tried to see the trimmers in each 
of the three holes - they appear to be some way within, and I am wondering 
if you could confirm the type of pot. that is used and just how long a 
trimming device is required. Is this a special tool only available from 
Fluke ?

Regards
Roy Phillips.


-Original Message- 
From: J. L. Trantham

Sent: Saturday, March 08, 2014 10:09 PM
To: 'Discussion of precise voltage measurement'
Subject: Re: [volt-nuts] A Fluke 732A: Return it or keep it?

Charles,

What size batteries did you use for your external pack and where are you
located?  In other words, how long can your external battery pack 'survive'
keeping the 732A 'hot'?  Is the external pack recharged at Fluke or does it
have to make a round trip on the initial charge?  Once I am convinced my
unit is stable (which will probably be another six months or so, after I get
my 3458A's re-calibrated by Agilent), I hope to be able to send it to Fluke
for calibration.

Fluke made a transit case (732A-7002) and a Battery Charger and Auxiliary
Battery Case (732A-7003).  However, I have never seen a picture of either of
these.  Does anyone have any information on these?

How did you make your case?  Did you include a charger?  Combination of
battery pack and shipping container or separate battery pack and shipping
container?

I was thinking of building a case with built-in charger, fuse, and AC
connector and cord such that when the unit arrived at the CAL facility all
that would be needed would be to plug it in and allow the external battery
pack to recharge while the unit being calibrated was plugged in, recharge
the internal batteries, and calibrated.  Or does the 732A also charge the
external battery pack along with the internal batteries?

The connector you need (complete with female contacts) is a Hypertronics P/N
D01PB306FSTAH and is in stock at Kensington Electronics at $8.96 each (plus
tax and shipping).  Only problem is their $50 minimum order.

The 'shell' only is P/N D01PB306NT and the female contact is P/N
YSK006-010ANH (three needed).

http://ecommerce.keiconn.com/hypertronics/D01PB306FSTAH

I ordered two of the connectors from Fluke using a P/N that one of the Fluke
folks in their eCal facility gave me, noting that someone else had asked the
same question a couple of weeks earlier, with Fluke Item# 2181497, described
as '100-166, PLUG - MALE, HYPERTRONICS'.  They were $12.31 each (plus tax
and shipping) and arrived as the shell only, no contacts.

If Fluke solves their supply chain problem, I sure would like to get the six
female contacts I need to make my connectors 'complete'.  When I got on the
phone with Fluke, I could never find anyone that had any knowledge about
this.  Is there anyone there I should ask for that might understand my
question?

I look forward to your posting the update from Fluke.

Thanks.

Joe


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Re: [volt-nuts] Fluke 732A Questions

[R.Phillips]

Joe
Reference the thermistor value and its recorded value - I asked Fluke this 
question and the answer was, they did supply the individual 732A's value in 
written form to the original purchaser, but unfortunately they did not 
maintain a separate record.

Roy

-Original Message- 
From: J. L. Trantham

Sent: Tuesday, December 31, 2013 1:22 PM
To: 'Discussion of precise voltage measurement'
Subject: Re: [volt-nuts] Fluke 732A Questions

Charles,

I would like to find the mating plug for J10 for several reasons, being able
to get it to calibration being just one of them.  However, I was hoping it
would be good enough to make it to calibration on the internal batteries.

I seem to recall reading that the internal batteries were good for a few
hours but nothing like what the 732B would do, which sounded like the 732B
could make the trip on the internal batteries.

Where did you find the resistance of the thermistor 'as shipped'?  I saw
mention of being supplied to the original owner when shipped as well and I
have had the top cover off and the battery module out to replace the
batteries and found nothing to suggest a thermistor value.  I have also
lifted the top layer of insulation off the oven to move the cal-jumpers but
did not see anything that suggested a thermistor value.

My 'metrology level' standards are my HP 3458A's, calibrated by Agilent, and
Solartron (Ametek) 7081's calibrated by Ametek.  I have been thinking of
getting the 732A calibrated by Fluke but I didn't know if they would still
calibrate the unit.  I wonder if they would have the 'as shipped' thermistor
value on file for my specific serial number?

I, too, read about the stability of the thermistor being the most important
measurement.  That was in the 'change sheets' attached to the manual on
Didier's site.

The 'cal-jumper' was at '40' when I got the unit.  Per my 3458A, I could
only get it down from about +220 uV to about +100 uV with the front panel
adjustment.  By moving the jumper to '20', I could only get it up to about
-12 uV below 10 V by turning the adjustment all the way in the opposite
direction.  However, by connecting jumpers for both the '20' and '10', I was
able to get it at 10 V with the front panel adjustment at about center
position.  I have not 'logged' any values yet but every time I go to the
shop, it is about +/- 1 or 2 uV from 10 V.  I do the 'AUTO CAL' on the 3458A
each morning I go into the shop.

I measure the resistance with a Fluke 8050A (simply because it is the
closest DMM to the standard) and it is 4229 to 4230 ohms each day.

Interestingly, when I got the 732A, undisturbed Fluke Calibration stickers
were in place over each of the adjustments on the front panel, on a back
screw on the top cover, and 'half' of a sticker on the back over the power
supply module, as if the other half was lost when someone removed the
battery module.  Somehow, I find that comforting, given that it now seems so
stable, making me think it is 'normal aging' that is responsible for the
values I measured rather than a problem with the oven, etc..  IIRC, the spec
is 6 ppm per year for 10 V, or 60 uV per year.  I'll have to look at the
power supply module to see if I can find some date codes but I suspect the
unit is 25 to 30 years old.  Unfortunately, there were no 'dates' on the
stickers to tell when the unit was last calibrated.

I was thinking of sending the 3458A's and the 732A out for calibration
simultaneously and seeing what I find when they get back.

I'll call Fluke and ask about their Cal services, the plug, and the shipping
case/battery pack issues.

Thanks everyone for very useful information.

Joe

-Original Message-
From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On
Behalf Of Charles Steinmetz
Sent: Monday, December 30, 2013 11:23 PM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Fluke 732A Questions

Joe wrote:


Also, how do you get your 732A calibrated?  Do the batteries last long
enough to ship overnight to a facility?


No -- I assumed that was why you were looking for a battery connector.  You
install an external battery for shipment overnight.  Fluke can supply a
complete external battery with cable and plug ($375, last I knew), or you
can make your own.  I believe they can also supply a shipping container,
which has a dedicated space for the Fluke external battery.  (If you don't
use Fluke's container, build something very sturdy with wood and padding and
with handles that make it hard not to carry it and set it down right side
up.)

I wouldn't have anybody but Fluke calibrate a 732A.  There are 3 levels of
calibration, all with data, from about $700 to about $1500 (the last is
calibration by Fluke's Primary Standards Lab).

As far as thermistor values go, the relevant question is not what is the
value in absolute terms, but rather what is the value in relation to the "as
manufactured" value, which was provided by Fluke when the unit shipped.
This had

Re: [volt-nuts] Fluke 732A Questions

[R.Phillips]

Hi Todd
I would appreciate a copy of your later issue manual for the 732A - please 
let me know when you make this available  -  Dider's site ?

Many thanks
Roy


-Original Message- 
From: T. Micallef

Sent: Monday, December 30, 2013 4:03 AM
To: volt-nuts@febo.com
Subject: Re: [volt-nuts] Fluke 732A Questions

Joe,

I don't know if it makes any difference but my manual is for the 732A/AN p/n
788414

I found a couple of brochures that I scanned and uploaded too.

I forgot to mention, I have been collecting information regarding the
techniques used to do intercomparisons using scanners like the Data Proof
models. While searching a couple of weeks ago, I came across an old document
from a Measurement Science Conference back in 1983. The document contains an
article regarding the testing of the Fluke 735C. I thought you may have
little to no info regarding your reference and thought I would let you know
about it.

The document is easy to find using google. It is named MSC1983.pdf
I will upload it as well, but I was not sure if Didier wants to track
conference docs.

Todd





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Re: [volt-nuts] Fluke 732A Questions

[R.Phillips]

Hi Joe
I also obtained a Fluke 732A back in October last, and I have fitted a new 
set of SLA batteries and it is working just fine - I am still very impressed 
by its accuracy and stability, and its build quality.
First, the external 3-pin power socket is a HYPERTRONICS 'D' type connector 
(female) type 100-166 - but I have not found one to date !
I also expected the temperature monitoring thermistor to give a 3 to 4 K 
ohms, as indicated in the manual P/N 645051 dated May 1983 - but I guess 
that you have a later model as I do, mine being serial # 4845***, some 
modifications were made,and I understand that this included a change of 
thermistor, so the standard reading is in keeping with your result. My unit 
gives a very stable 4.520 K ohms, being between 4.52080 and 4.52090 K ohms. 
Judging by your findings, you are also using the 1983 copy of the User 
Manual - we could both use a more up to date issue.
I am awaiting the repair of my 3458A - so I am having to rely upon a 
recently calibrated Keithley 2015 and my good old 3456A - but they both give 
very impressive results - The Keithley giving 1.07 volts for the 1 volt 
output, and 10.0 volts for the 10 volt output (how I miss that final 
digit).

Looking forward to your further results and any other owners comments.
Best regards

Roy


-Original Message- 
From: J. L. Trantham

Sent: Saturday, December 28, 2013 10:51 PM
To: volt-nuts@febo.com
Subject: [volt-nuts] Fluke 732A Questions

I have reviewed the prior postings on Volt-nuts (a very rewarding review,
BTW)) regarding the 732A and have two questions:



1.Has anyone determined the part number, or a source, for the mating
plug to J10, the external power connector for the 732A-7005 battery pack?  I
noted some postings recently about this but did not find a definitive
response regarding the identity of this plug.  The alternative would appear
to be a complete replacement of J10 and its plug, as long is it all fits in
the opening in the panel.  I hate to 'bore holes' in vintage equipment.

2.   The oven thermistor in my 'new to me' unit measures 4229 ohms (+/-
an ohm or two) after the unit has warmed up for a week or so.  I note the
manual refers to 3K to 4K for the value of this thermistor when the unit is
'stable' as well as other's posting values in the mid 3500's ohms for their
units.  Should I be concerned?  The unit seems to be stable to within about
2 uV over about a week (as measured by my 3458A - see below).  Should I open
the unit and try to measure the oven temperature or just be satisfied that
the unit seems to be working?



I had to replace the four 6V 4AH SLA batteries and they charged up
appropriately as judged by the front panel LED's.  I had to remove the
'jumper' for the '40' option on the A7 board and connect the jumper to the
'20' and '10' options (total of '30') in order to get the unit to adjust to
10.000 VDC on my 'Agilent In Cal'd' 3458A.



The need to change the jumpers, perhaps, could be just an ageing issue or,
on the other hand, a 'temperature' issue with the oven.



Should I open the unit and directly measure the temperature (supposedly
about 48 degrees C) or just be satisfied with what I have?



My recently added 735C also needed moving some 'jumpers' in order to get it
'on scale', as determined by my 3458A, although it's thermistor measures
about 3330 ohms (after being on for several weeks).



Thanks for everyone's help.



Joe







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Re: [volt-nuts] The Fluke 732A DC Reference Standard

[R.Phillips]

Bill
Its interesting that you have reverted to the original AC/DC external supply
connectors - the two 4 mm sockets. My guess is that they moved away from
this set-up as it was probably all to easy to make connections to external
equipment - as the 27.6 volts is also available at these sockets !
Your remarks reference the quickly established stable output is exactly as I
found within 48 hours, remember my instrument had taken a ride in an 
aircraft hold from

the West Coast, USA  to London, UK,  and it still recovered quickly ! The
great difference between the 732A and my 731B's is obviously temperature
stability - the oven makes this a winning factor. In fact I am very
impressed by the stability of the oven, the independent thermistor reads
4.520 K ohms +/- 1 ohm consistently. The move to gelled lead acid batteries
was also an improvement, despite the weight factor - the 731b's were 
frequently

damaged by failed Ni-Cads. And then also the rotary voltage selector switch,
this can be a source of trouble.
Thanks again.
Roy

-Original Message- 
From: Bill Gold

Sent: Tuesday, November 05, 2013 3:49 PM
To: volt-nuts@febo.com
Subject: Re: [volt-nuts] The Fluke 732A DC Reference Standard

Roy,
   I have a later manual for the 732A.  P/N 788414 May 1986.  This manual
shows the little 3 pin connector labeled J10 for the battery module.  The
parts list shows a Fluke stock #720844, Mfg 89536 (Fluke) and Mfg P/N
720844.  I have long since removed it from my 732As and replaced it with two
minature banana jacks (2.64mm) red and black.  There seems to be some sort
of Mfg mark on the 3 pin connector but I cannot identify it ( I saved the
old 3pin connectors).  If the manual you downloaded is from the Fluke
website and is named "732Aimeng.pdf" or "732A_Users_Manual.pdf" you
will see a "Change/Errata Information, 7/85" list in the front of the file.
Change #5 changes the battery connections to the spade lugs and Change #6
changes the banana jacks to the 3 pin connector.
You were very wise in removing some metal from the top plate to allow plenty
of room for the spade lugs on the new batteries.  I didn't do this intially
and one of the battery terminals shorted to the metal plate and fried the +
18 volt regulator assembly, which took a few days to fix.  My opinion of the
732A vs. the 732B is that since the 732A has been around longer the
references have had a longer time to stabilize.  The only issue I know of
732A vs. 732B is the battery life.  The 732A battery life is around 12 to 15
hours without being powered.  The 732B specs the battery life at around 72
hours.  This makes it easier to get it to Fluke in Everett WA without losing
the "IN CAL" light.  My experience is that even when started from cold after
being off for a long period of time they will stabilze at exactly the
voltage they had when the power was turned off.  It does take a few days
however.
Bill
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[volt-nuts] The Fluke 732A DC Reference Standard

[R.Phillips]

Fellow Volt-nuts
I have recently acquired a Fluke 732A which required a new set of 6 volt, 4 Ah 
batteries which after some re-working of the top plate of the battery 
compartment, to accommodate the lugs of the Yuasa cells are now installed and 
working fine. I am very pleased with this instrument having spent 12 or more 
years with two 731B’s . The oven stability is very good, a resistance of 4.520 
K ohms being within +/-1 ohm.  I have a down-loaded manual P/N 645051, May 1983 
which is somewhat ‘out of date’ for my instrument which was issued 1989/90. Is 
it possible that anyone has a later issue ? For example, the rear AC/DC support 
power supply input in my manual copy shows a pair of 4 m/m, where mine has a 
3-pin socket (male) for this purpose. Anyone know the type/manufacturer of this 
item ?
This is a very well made instrument, and I gather that many think it better 
than the 732B ? Any help would be appreciated.
Roy
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Re: [volt-nuts] UK Fluke book Calibration: Philosophy in practice UKebay good price

[R.Phillips]

Robert
Thank you for the information. I was fortunate in obtaining a 2nd edition 
hardback copy, in mint condition from a Hospice shop in the UK for £40 plus 
postage, just a month ago. Excellent book !!!

Roy P


-Original Message- 
From: Robert Atkinson

Sent: Sunday, September 15, 2013 12:26 PM
To: volt-nuts@febo.com
Subject: [volt-nuts] UK Fluke book Calibration: Philosophy in practice 
UKebay good price



Uk ebay item 331021831159 Fluke's Calibration: Philosophy in practice BIN 
£10 plus £7 P&P.

I have a copy but this is a good price. (Amazon UK is asking 10 times this).

Robert G8RPI
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Re: [volt-nuts] Fluke 510A

[R.Phillips]

Didier
I would agree generally with your remarks ref. the 34578A and the 3456A, I 
have both, but more recently I have acquired a Keithley 2015 which I guess 
is more in keeping with the 3478A, but with a fluorescent display, this is a 
very nice instrument to use, and is currently being sold in considerable 
numbers having been used by the 'mobile 'phone industry for its distortion 
measuring ability, the one I have was cal'd in 2009  -  -  I would be 
interested to hear from any other users.

regards
Roy P


-Original Message- 
From: Didier Juges

Sent: Sunday, August 11, 2013 2:52 AM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Fluke 510A

That is not completely true. The HP3456A has a full scale of 1,100,000 
compared to the HP3478A's 300,000

Not quite an order of magnitude.
I have both and while the display is not always visible, particularly in dim 
light, I like the smaller size and quiet operation of the HP3478A compared 
to the HP3456A. When the better specs (on paper) of the HP3456A are not 
absolutely needed, the HP3478A is  a fine bench meter.


Didier KO4BB


"Marv @ Home"  wrote:

A 6.5 or better will find a good home and be appreciated in your lab,
Joe.  Many orphans need homes always appear on eBay, particularly the
top line of its day HPs: 3455a, 3456a, and 3457a.

There is a lot of discussion on the pros and cons of each throughout
the archives, but any will be an order of magnitude better than the 5.5
digit.


At 02:33 PM 8/10/2013, Joseph Gray wrote:

Oops. It was getting late and I guess my fingers typed the wrong digit

:-).


Yes, I was thinking about getting a better DMM.

Joe Gray
W5JG




Sincerely,



Marv
Philadelphia, PA

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--
Sent from my Motorola Droid Razr 4G LTE wireless tracker while I do other 
things.

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Re: [volt-nuts] Rotek 320 AC/DC Calibrator

[R.Phillips]

Sorry for misspelt name - it is of course Rotek  (Weston - Rotek)
Roy


-Original Message- 
From: R.Phillips

Sent: Tuesday, August 06, 2013 3:24 PM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Rotek 320 AC/DC Calibrator



-Original Message- 
From: Marv @ Home

Sent: Tuesday, August 06, 2013 2:49 PM
To: j...@quikus.com ; Discussion of precise voltage measurement ; Discussion
of precise voltage measurement
Subject: Re: [volt-nuts] Rotek 320 AC/DC Calibrator

Thanks John, appreciated, not sure if they are similar as the unit is
in transit and not in my possession, its a boat anchor.  Will let
you'all know the status after a thorough evaluation.  Still doing
'discovery' and getting as much info as possible.


From a volt nuts perspective, for other readers, calibrators may

have very stable references in single digit ppm, and maybe an option
instead of build your own reference, plus they may come with built in
KV dividers, precision AC oscillators etc., that alone maybe worth
the whole kaboodle.  Some are dirt cheap, as low as free except
postage, others not so.


At 05:49 PM 8/2/2013, J. Forster wrote:

I'm not certain it's the same model, but the one I'm familiar with was in
a Wamco (formica) case, maybe 10" x 12" x 8" with some colored binding
posts. They has a little glass 'thermal convertor' about the size of a
pecan. The rest of the box was precision resistors and high quality
(Shallcross ?) switches.

There were a bunch of part-built ones surplused in the Boston area in the
late 1970s. Internally they had plexi panels with 0.1% and .01% resistors,
in decade values as I remember.

If that's the puppy, I know nothing more. I still have some of the parts
put away somewhere. I never had any paperwork AFAIK. They may have been
affiliated with Weston.

If this is not the puppy, never mind.  :)

-John

=




Sincerely,



Marv
Philadelphia, PA

Marv
Your recent discussion re. the ROTAX , (WESTON-ROTAX) Standard.
I have just "dug out" my Rotax 401A DC Absolute Voltage/Current Standard -
this provides 1. V dc, 1.0185 V dc, 9.9950 V dc. Current (16v), 7.50
mA, 10.00 mA
It gave very good results when last checked, built like a
proverbial - - - - - . It came from a lab. which was shut some years ago,
and I have no data -  I will be interested if you obtain more information on
these 'old timers'
Roy

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Re: [volt-nuts] Rotek 320 AC/DC Calibrator

[R.Phillips]

-Original Message- 
From: Marv @ Home

Sent: Tuesday, August 06, 2013 2:49 PM
To: j...@quikus.com ; Discussion of precise voltage measurement ; Discussion 
of precise voltage measurement

Subject: Re: [volt-nuts] Rotek 320 AC/DC Calibrator

Thanks John, appreciated, not sure if they are similar as the unit is
in transit and not in my possession, its a boat anchor.  Will let
you'all know the status after a thorough evaluation.  Still doing
'discovery' and getting as much info as possible.


From a volt nuts perspective, for other readers, calibrators may

have very stable references in single digit ppm, and maybe an option
instead of build your own reference, plus they may come with built in
KV dividers, precision AC oscillators etc., that alone maybe worth
the whole kaboodle.  Some are dirt cheap, as low as free except
postage, others not so.


At 05:49 PM 8/2/2013, J. Forster wrote:

I'm not certain it's the same model, but the one I'm familiar with was in
a Wamco (formica) case, maybe 10" x 12" x 8" with some colored binding
posts. They has a little glass 'thermal convertor' about the size of a
pecan. The rest of the box was precision resistors and high quality
(Shallcross ?) switches.

There were a bunch of part-built ones surplused in the Boston area in the
late 1970s. Internally they had plexi panels with 0.1% and .01% resistors,
in decade values as I remember.

If that's the puppy, I know nothing more. I still have some of the parts
put away somewhere. I never had any paperwork AFAIK. They may have been
affiliated with Weston.

If this is not the puppy, never mind.  :)

-John

=




Sincerely,



Marv
Philadelphia, PA

Marv
Your recent discussion re. the ROTAX , (WESTON-ROTAX) Standard.
I have just "dug out" my Rotax 401A DC Absolute Voltage/Current Standard - 
this provides 1. V dc, 1.0185 V dc, 9.9950 V dc. Current (16v), 7.50 
mA, 10.00 mA
It gave very good results when last checked, built like a 
proverbial - - - - - . It came from a lab. which was shut some years ago, 
and I have no data -  I will be interested if you obtain more information on 
these 'old timers'

Roy

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Re: [volt-nuts] Solartron 7150plus - Chasing AC gremlins

[R.Phillips]

Philip
Such resolve - bravery above and beyond the call of restoration - I have a 
Solartron 7150plus in good working order, after replacing its mains power 
input filter !!  -  but is it worth the effort.  I reckon the HP3478A is a 
much better instrument for about the same amount of money.

regards
Roy P


-Original Message- 
From: Philip Pemberton

Sent: Monday, December 24, 2012 2:06 PM
To: volt-nuts@febo.com
Subject: Re: [volt-nuts] Solartron 7150plus - Chasing AC gremlins

Right then, time for a writeup :)

Long story short - the 7150Plus is just about fixed. Parts were sourced
as follows:
 * Three 3N163 "analog switch" FETs at £11 each from Littlediode on
Ebay. These turned out not to be required...

 * Analog Devices AD637 (SOIC16) RMS-to-DC converted with SOIC breakout
board. About £30 of silicon and plastic... also not used (though may be
needed later if the 637 in the meter doesn't stop drifting).

 * Three LH0062H opamps. $45 US plus shipping for all three, or £27.81
in the Queen's currency - also obtained from ebay
().


To recap, the problem was that the AC ranges were drifting badly and
calibration reported an error condition after warm-up. After applying
freeze spray to the opamp/FET section of the AC stage, the whole AC
stage failed and the meter reported an input overload.

Initial investigations suggested that IC15 (LH0062C, National
Semiconductor) was running open loop (output was clipped to within a few
volts of the negative-15V rail). No reason for this could be readily
ascertained and the feedback loop was producing erroneous results when
probed with a DMM (due to the opamp feeding back into the circuit).

Initially I suspected IC18 (DG211, Siliconix) and replaced it. This had
no effect on the failure symptoms.

This morning I desoldered the LH0062C and replaced it with an 8-pin IC
socket (machined-pin type of course). Probing the opamp support
circuitry with the opamp out of circuit suggested that the attenuator
and feedback loop were now operating as per the service manual description.

For "Gain of 10" ranges, resistance between IC15 pin 6 and IC15 pin 2
was measured at 1M-ohm after a settling delay of several tens of
seconds. The settling delay can be attributed to the charging of C29
(3u3); the resistance is from R72 (1Meg). TR12 (WN1001) appears to
prevent the multimeter from measuring the R21a/R21b divider chain.

For "Gain of 1" (unity) ranges, IC18 SW3 (pins 9, 10, 11) shorts over
C24 and puts the opamp into a unity gain state. Resistance between IC15
pins 6 and 2 is approximately 30 Ohms in this mode.

The function of TR12 and the circuitry around it still elude me. I've
never been much good with JFET circuits!

After replacing the opamp, the AC range was selected with a 2V range.
This sets the attenuator to 1:1 mode and IC15's gain to unity. The whole
AC chain now acts as a buffer. Applying a 2V pk-pk (~0.7V RMS) 400Hz
sine to the input with a signal generator and probing the opamp output
at TP3 suggested that the opamp was now functioning to spec. Testing the
AC ranges suggests that aside from some expected calibration issues, the
meter is functioning normally.

I'm hoping that trimming the offset is as simple as grounding the input,
selecting the lowest AC voltage range and adjusting for zero volts at TP3.

After that, I need to figure out how to calibrate the AC voltage and
current ranges! I'm hoping the signal generator will work for the lowest
ranges, but the 20V, 200V and 750V ranges (not to mention the AC current
range) may prove somewhat tricky...

Then finally I need to remove the front panel and re-glue it to the
plastic base. Unfortunately the old glue (actually double-sided tape)
has perished and the front panel is now looking a little sorry for itself...

Thanks,
--
Phil.
phil...@philpem.me.uk
http://www.philpem.me.uk/

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Re: [volt-nuts] The HP 8903A Audio Analyzer

[R.Phillips]

Will
I am very grateful for this help.
Many thanks to you.
Roy


-Original Message- 
From: Will

Sent: Wednesday, September 19, 2012 9:14 AM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] The HP 8903A Audio Analyzer

http://www.ko4bb.com/Manuals/HP_Agilent/HP_8903A_Audio_Analyzer-Service.pdf


2012/9/18, Roy Phillips :

I have a faulty HP8903A. Despite the excellent Agilent manual archive, and
other sources that I am aware of – I cannot find any source for the 
Service

Manual – can anybody help ?  The unit starts up and displays all digits as
with the normal “self check”, but stops dead at this stage. All voltages
would appear to be normal. It has a sequence of four yellow LED’s on the
Processor PCB, which are active – but what is the ‘normal’ state for 
these.

This is not an easy unit to access without the vertical series of PCB’s
without extenders – any help would be much appreciated.
Thanks
Roy
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