Re: [volt-nuts] 3458A reference boards on ebay (Dave M)
Hi, Does anyone have a "clean" 3458A reference board, ie PCB without components? Throw it in the copier? Or would that violate some copyright? In that case, a board outline (board measurements, hole and connector footprints ...) would be enough. I don't have a 3458A to dig into, otherwise, I'd do it. I'd be happy to make new PCB if someone sends the info. Jan ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 3458A reference boards on ebay
Hendrik,
Thanks for sharing your design. I have looked at the Rhopointasia.com
website and I noticed they had the squaristors. They appear to be of a
similar size to the Vishay metal foil resistors. It would appear you might
save some space on your design using radial packages. I have not seen these
mentioned by other users and I would be interested to see some real-world
data.
Todd
On Sat, Jan 31, 2015 at 2:59 AM, Hendrik Dietrich wrote:
>
> Am 31.01.2015 06:21, schrieb Joel Setton:
>
>> I'll be happy to design a PCB, and have bare PCB prototypes made.
>> Sourcing parts and purchasing them will be another, larger project!
>>
>> Joel Setton
>>
>>
> Here's my design in eagle, the prototype is working fine but there is
> still room for improvement:
>
> http://dg3hda.primeintrag.org/lib/exe/fetch.php?media=rev0-econi.zip
>
> Free for volt-nut useage, of course.
>
> I tried to remove some voodoo that you will be told if using the internet
> as source, but there are leftovers as I was afraid that they could have
> something:
>
> There are some extra cuts close to the connectors ("stress relief") which
> are really unnecessary - after manufacture I became aware of a experiment
> reported on EEVBlog that strong bending with a vise gave no visible
> response of a LM399-based PCB on 6.5 digit DVMs.
>
> A few drills around the LTZ itself which are cheaper to produce but might
> or might not have some benefit - kovar lead and soldering joint are
> thermally closer to the temperature controlled site, so less risk of
> _changing_ EMF voltages there.
>
> The opamp at the output causes some tiny little degradation but gives a
> lot of protection in case of accidents and abuse.
> This core circuit can be pushed around to make it much more compact, if
> somebody does it the regained space should be used to add some filtering
> against EMI.
>
> The resistors are not Vishay but Rhopoint Econistors. My LTZ1000A was
> sourced from ebay, and no dud.
>
> Hendrik
>
>
> ___
> volt-nuts mailing list -- volt-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/volt-nuts
> and follow the instructions there.
>
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
Re: [volt-nuts] 3458A reference boards on ebay
Am 31.01.2015 06:21, schrieb Joel Setton:
I'll be happy to design a PCB, and have bare PCB prototypes made.
Sourcing parts and purchasing them will be another, larger project!
Joel Setton
Here's my design in eagle, the prototype is working fine but there is
still room for improvement:
http://dg3hda.primeintrag.org/lib/exe/fetch.php?media=rev0-econi.zip
Free for volt-nut useage, of course.
I tried to remove some voodoo that you will be told if using the
internet as source, but there are leftovers as I was afraid that they
could have something:
There are some extra cuts close to the connectors ("stress relief")
which are really unnecessary - after manufacture I became aware of a
experiment reported on EEVBlog that strong bending with a vise gave no
visible response of a LM399-based PCB on 6.5 digit DVMs.
A few drills around the LTZ itself which are cheaper to produce but
might or might not have some benefit - kovar lead and soldering joint
are thermally closer to the temperature controlled site, so less risk of
_changing_ EMF voltages there.
The opamp at the output causes some tiny little degradation but gives a
lot of protection in case of accidents and abuse.
This core circuit can be pushed around to make it much more compact, if
somebody does it the regained space should be used to add some filtering
against EMI.
The resistors are not Vishay but Rhopoint Econistors. My LTZ1000A was
sourced from ebay, and no dud.
Hendrik
___
volt-nuts mailing list -- volt-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
and follow the instructions there.
Re: [volt-nuts] 3458A reference boards on ebay
http://www.ebay.com/itm/Agilent-Keysight-HP-3458A-Std-Ref-Board-NIST-certified-/310249132548?pt=LH_DefaultDomain_0&hash=item483c4a1204 Try this one... It has a 30 day return and you get a cal voltage with it. On Fri, Jan 30, 2015 at 9:21 PM, Joel Setton wrote: > I'll be happy to design a PCB, and have bare PCB prototypes made. > Sourcing parts and purchasing them will be another, larger project! > > Joel Setton > > > On 30/01/2015 14:24, Dr. David Kirkby (Kirkby Microwave Ltd) wrote: > >> On 30 January 2015 at 12:25, Will wrote: >> >>> The boards are factory rejects. >>> >> I doubt all boards on eBay are in this category. Some are probably >> quite genuine, some may be rejects, and it would never surprise me if >> some are counterfeit. The problem is, I have no idea what ones are >> what. >> >> I don't know what the problems sourcing the parts for making a >> reference would be, but if a number of people wanted to make one from >> parts, perhaps someone could produce a PCB and people contribute >> towards the cost of it. Maybe leave people to get their own reference >> chip, as there are different grades of that. But things like the >> precision resistors may be easier to buy in a quantity of 10 rather >> than 1. >> >> I would certainly not mind buying one if a PCB was available. Even if >> it works out costing a bit more than a 3458A reference from eBay, I'd >> feel a bit happier. >> >> Dave >> ___ >> volt-nuts mailing list -- volt-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/ >> mailman/listinfo/volt-nuts >> and follow the instructions there. >> >> > ___ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/volt-nuts > and follow the instructions there. > -- *John Phillips* ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 3458A reference boards on ebay
I'll be happy to design a PCB, and have bare PCB prototypes made. Sourcing parts and purchasing them will be another, larger project! Joel Setton On 30/01/2015 14:24, Dr. David Kirkby (Kirkby Microwave Ltd) wrote: On 30 January 2015 at 12:25, Will wrote: The boards are factory rejects. I doubt all boards on eBay are in this category. Some are probably quite genuine, some may be rejects, and it would never surprise me if some are counterfeit. The problem is, I have no idea what ones are what. I don't know what the problems sourcing the parts for making a reference would be, but if a number of people wanted to make one from parts, perhaps someone could produce a PCB and people contribute towards the cost of it. Maybe leave people to get their own reference chip, as there are different grades of that. But things like the precision resistors may be easier to buy in a quantity of 10 rather than 1. I would certainly not mind buying one if a PCB was available. Even if it works out costing a bit more than a 3458A reference from eBay, I'd feel a bit happier. Dave ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 3458A reference boards on ebay
Most likely the boards are real, especially if the boards are from a seller in Colorado since that is where Keysight in the past manufactured and serviced all 3458A's. They still do all calibration in Loveland (I am not sure if Loveland is where service is done today) but this would mean the boards are pulls for either up grade to 002 or HFL boards or worse failed to meet spec. Further I would guess that working boards that meet spec would be retained for future replacements. That said the ones listed do appear genuine. If someone was thinking of duplicating the PCB I may be able to provide one to disassemble and repopulate afterwards. It would be interesting to have a few boards to experiment with. Cheers; Thomas Knox > Date: Fri, 30 Jan 2015 13:24:30 + > From: drkir...@kirkbymicrowave.co.uk > To: volt-nuts@febo.com > Subject: Re: [volt-nuts] 3458A reference boards on ebay > > On 30 January 2015 at 12:25, Will wrote: > > The boards are factory rejects. > > I doubt all boards on eBay are in this category. Some are probably > quite genuine, some may be rejects, and it would never surprise me if > some are counterfeit. The problem is, I have no idea what ones are > what. > > I don't know what the problems sourcing the parts for making a > reference would be, but if a number of people wanted to make one from > parts, perhaps someone could produce a PCB and people contribute > towards the cost of it. Maybe leave people to get their own reference > chip, as there are different grades of that. But things like the > precision resistors may be easier to buy in a quantity of 10 rather > than 1. > > I would certainly not mind buying one if a PCB was available. Even if > it works out costing a bit more than a 3458A reference from eBay, I'd > feel a bit happier. > > Dave > ___ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 3458A reference boards on ebay
I'd go for a deal like that as well. I have a small number of LM399s that I'd like to put to use, as well as a couple LTZ1000A references. A project using either type of reference would be very exciting for me. I have a few old Fluke differential meters that have lots of nice low tempco, high quality resistors that might finally find a useful project such as this. Count me in, Dave M. Dr. David Kirkby (Kirkby Microwave Ltd) wrote: On 30 January 2015 at 12:25, Will wrote: The boards are factory rejects. I doubt all boards on eBay are in this category. Some are probably quite genuine, some may be rejects, and it would never surprise me if some are counterfeit. The problem is, I have no idea what ones are what. I don't know what the problems sourcing the parts for making a reference would be, but if a number of people wanted to make one from parts, perhaps someone could produce a PCB and people contribute towards the cost of it. Maybe leave people to get their own reference chip, as there are different grades of that. But things like the precision resistors may be easier to buy in a quantity of 10 rather than 1. I would certainly not mind buying one if a PCB was available. Even if it works out costing a bit more than a 3458A reference from eBay, I'd feel a bit happier. Dave ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 3458A reference boards on ebay
There is currently a thread on EEVBlog where one has already been built. I believe it can be purchased once the final layout is completed. http://www.eevblog.com/forum/projects/project-kx-diy-calibrator-reference-sourcemeter/ Todd On Fri, Jan 30, 2015 at 8:24 AM, Dr. David Kirkby (Kirkby Microwave Ltd) < drkir...@kirkbymicrowave.co.uk> wrote: > On 30 January 2015 at 12:25, Will wrote: > > The boards are factory rejects. > > I doubt all boards on eBay are in this category. Some are probably > quite genuine, some may be rejects, and it would never surprise me if > some are counterfeit. The problem is, I have no idea what ones are > what. > > I don't know what the problems sourcing the parts for making a > reference would be, but if a number of people wanted to make one from > parts, perhaps someone could produce a PCB and people contribute > towards the cost of it. Maybe leave people to get their own reference > chip, as there are different grades of that. But things like the > precision resistors may be easier to buy in a quantity of 10 rather > than 1. > > I would certainly not mind buying one if a PCB was available. Even if > it works out costing a bit more than a 3458A reference from eBay, I'd > feel a bit happier. > > Dave > ___ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 3458A reference boards on ebay
On 30 January 2015 at 12:25, Will wrote: > The boards are factory rejects. I doubt all boards on eBay are in this category. Some are probably quite genuine, some may be rejects, and it would never surprise me if some are counterfeit. The problem is, I have no idea what ones are what. I don't know what the problems sourcing the parts for making a reference would be, but if a number of people wanted to make one from parts, perhaps someone could produce a PCB and people contribute towards the cost of it. Maybe leave people to get their own reference chip, as there are different grades of that. But things like the precision resistors may be easier to buy in a quantity of 10 rather than 1. I would certainly not mind buying one if a PCB was available. Even if it works out costing a bit more than a 3458A reference from eBay, I'd feel a bit happier. Dave ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 3458A reference boards on ebay
The boards are factory rejects. I bought five of them several years ago when the price was around $40. One of them had the heater transistor flipped. Worked fine after reversing the transistor. One had misaligned connector, which would have been easy to repair but the HP policy seems to be reject rather than repair small boards. One had corner of the Vishay resistor cracked. Two of them were cosmetically perfect but had much higher noise than others. Be prepared that there is always something wrong. Could be a good idea to prefer those with some obvious cosmetic problem... > I am puzzled why there are so many reference boards that are supposed to > come from 3458As on the used market. It makes me wonder if they are > genuine. > > One seller, with the two high stability reference boards at $750, claims > that they come from working and recently calibrated 3458As. Why would > anyone wreck a working and recently calibrated 3458A? > > It is not beyond the bounds of possibility that a 3458A might be worth more > in parts than as a complete unit. I know this is true for some HP items, > but I doubt that is the case with a 3458A. > > Another seller, who has them at $395 "or offer", has sold 17 and has 11 > left. > > Although expensive, having two and monitoring the difference between them > would probably allow their stability to be measured with a DVM of modest > specification. > > There are lots of counterfeit components around, and I fear that it could > be some of these boards could fall into that category. This makes the > building a board from new components more attractive. In the short term it > is likely to be less stable than an old reference, but at least one would > know the history of it. If the components were sourced from reliable > sources, it would get around the potential counterfeit problem. > > Dave. > ___ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 3458A reference boards on ebay
RE: "One seller, with the two high stability reference boards at $750, claims that they come from working and recently calibrated 3458As. Why would anyone wreck a working and recently calibrated 3458A? " Some contracts may require the more stable reference and the standard reference is pulled to make room for the option 002. I know I have done that at lest 30 times. On Thu, Jan 29, 2015 at 12:59 PM, Dr. David Kirkby (Kirkby Microwave Ltd) < drkir...@kirkbymicrowave.co.uk> wrote: > On 27 Jan 2015 09:47, "Orin Eman" wrote: > > > > There is a seller letting a slow trickle of them out there... they seem > to > > be going for about $165. The current batch of two is around $100, but > will > > probably be bid up. > > I am puzzled why there are so many reference boards that are supposed to > come from 3458As on the used market. It makes me wonder if they are > genuine. > > One seller, with the two high stability reference boards at $750, claims > that they come from working and recently calibrated 3458As. Why would > anyone wreck a working and recently calibrated 3458A? > > It is not beyond the bounds of possibility that a 3458A might be worth more > in parts than as a complete unit. I know this is true for some HP items, > but I doubt that is the case with a 3458A. > > Another seller, who has them at $395 "or offer", has sold 17 and has 11 > left. > > Although expensive, having two and monitoring the difference between them > would probably allow their stability to be measured with a DVM of modest > specification. > > There are lots of counterfeit components around, and I fear that it could > be some of these boards could fall into that category. This makes the > building a board from new components more attractive. In the short term it > is likely to be less stable than an old reference, but at least one would > know the history of it. If the components were sourced from reliable > sources, it would get around the potential counterfeit problem. > > Dave. > ___ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > -- *John Phillips* ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 3458A reference boards on ebay
On 27 Jan 2015 09:47, "Orin Eman" wrote: > > There is a seller letting a slow trickle of them out there... they seem to > be going for about $165. The current batch of two is around $100, but will > probably be bid up. I am puzzled why there are so many reference boards that are supposed to come from 3458As on the used market. It makes me wonder if they are genuine. One seller, with the two high stability reference boards at $750, claims that they come from working and recently calibrated 3458As. Why would anyone wreck a working and recently calibrated 3458A? It is not beyond the bounds of possibility that a 3458A might be worth more in parts than as a complete unit. I know this is true for some HP items, but I doubt that is the case with a 3458A. Another seller, who has them at $395 "or offer", has sold 17 and has 11 left. Although expensive, having two and monitoring the difference between them would probably allow their stability to be measured with a DVM of modest specification. There are lots of counterfeit components around, and I fear that it could be some of these boards could fall into that category. This makes the building a board from new components more attractive. In the short term it is likely to be less stable than an old reference, but at least one would know the history of it. If the components were sourced from reliable sources, it would get around the potential counterfeit problem. Dave. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 3458A reference boards on ebay
Orin, What do you intend doing with it? I was thinking about getting one of those, with a view to putting it in a box with a couple of terminals to have something to compare with my 6.5 digit 3457A. But what put me off is a lack of knowledge in knowing how to convert a 3458A reference board into a boxed unit with a known output voltage at the terminals. How would I avoid / control thermal EMFs? I'd be interested to hear what your plans are for it, and how you intend tackling those issues. Do you know what the difference in the reference is between a standard 3458A (8 ppm) and the high stability option 002 (4 ppm) model? I'm guessing the chips for the option 002 might be the top performing ones. I wonder if there's any way to tell from your board if it came from a standard 3458A or a 3458A with option 002. Dave Take a look at this site for some good info on using the 3458A reference: http://www.maxmcarter.com/vref/ Tony H ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 3458A reference boards on ebay
These various Keysight/Agilent/HP references are selected during aging but are all identical in parts and layout. Most of these references improve with age and after time many standard references will meet or exceed the performance of 002 or even the 2PPm HFL boards. The question on these eBay boards is are they ones that failed to meet factory specs. What I often wonder is in this era of JJA's why has no one built a better reference like has been done with Quartz oscillators for many decades? Cheers; Thomas Knox > From: wpgold3...@att.net > To: volt-nuts@febo.com > Date: Tue, 27 Jan 2015 08:20:50 -0800 > Subject: Re: [volt-nuts] 3458A reference boards on ebay > > > - Original Message - > From: "Dr. David Kirkby (Kirkby Microwave Ltd)" > > To: "Discussion of precise voltage measurement" > Sent: Tuesday, January 27, 2015 2:24 AM > Subject: Re: [volt-nuts] 3458A reference boards on ebay > > > > On 27 January 2015 at 09:16, Orin Eman wrote: > > > There is a seller letting a slow trickle of them out there... they seem > to > > > be going for about $165. The current batch of two is around $100, but > will > > > probably be bid up. > > > > > > I just received one that I won. Seems to be working fine after a quick > > > breadboard lashup. I'll be making an enclosure for it next. > > > > > > A little expensive IMO, but given the trouble getting the precision > > > resistors to DIY with the LTZ1000A, probably worth it. > > > > > > Orin > > > > Orin, > > > > What do you intend doing with it? > > > > I was thinking about getting one of those, with a view to putting it > > in a box with a couple of terminals to have something to compare with > > my 6.5 digit 3457A. But what put me off is a lack of knowledge in > > knowing how to convert a 3458A reference board into a boxed unit with > > a known output voltage at the terminals. How would I avoid / control > > thermal EMFs? > > > > I'd be interested to hear what your plans are for it, and how you > > intend tackling those issues. > > > > Do you know what the difference in the reference is between a standard > > 3458A (8 ppm) and the high stability option 002 (4 ppm) model? I'm > > guessing the chips for the option 002 might be the top performing > > ones. I wonder if there's any way to tell from your board if it came > > from a standard 3458A or a 3458A with option 002. > > > > Dave > > Dave: > > The 002 reference boards have another label on them marked 03458-66519 > which overlays the etched number on the PC board. As a matter of fact see > the new listing on evilbay 271754789913. The super ultra stable 2ppm is > marked 03458-66529 to the best of my knowledge. > > Bill > > > ___ > > volt-nuts mailing list -- volt-nuts@febo.com > > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > > and follow the instructions there. > > ___ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 3458A reference boards on ebay
Dave, I'll be putting it in an enclosure to use as a reference. It will probably be a smallish diecast aluminium box. It's what I did with my Geller SVR-T and it compared very well with my Fluke 731B. I'll likely use Pomona 3770 binding posts for output (I used them to repair the 731B). I'll also use the protection circuits from the Fluke 732 on the output - big reverse diode, gas discharge tube and TVS as I recall (I plan to add these protection circuits to the 731B). I'll likely do a PCB for it, though the local equivalent of veroboard would likely be OK; the socket spacing is 0.9" and the pin spacing 0.1". My meters are also 6 1/2 digit (3456A and 34461A) so I'm not too concerned with thermal EMFs with one count being 10uV on the 10V range. However, I will try to avoid temperature gradients and keep the outputs close together. I'll use star wiring for the 18V and ground as in the following: http://www.maxmcarter.com/vref/ It is debatable whether the -15V supply is needed - I'll test with and without. I'd add a few tantalum capacitors to the above design - on the regulator outputs and on the 3320 resistor, along with protection diodes for the LM317. There is also a HUGE thread about the LTZ1000 on EEVBlog - I'll be reviewing that for ideas: http://www.eevblog.com/forum/projects/ultra-precision-reference-ltz1000/ I actually have a couple of LTZ1000As here that I was going to DIY, but never got around to getting the precision resisters . I think there is a source in England mentioned in the EEVBlog thread. Orin. On Tue, Jan 27, 2015 at 2:24 AM, Dr. David Kirkby (Kirkby Microwave Ltd) < drkir...@kirkbymicrowave.co.uk> wrote: > On 27 January 2015 at 09:16, Orin Eman wrote: > > There is a seller letting a slow trickle of them out there... they seem > to > > be going for about $165. The current batch of two is around $100, but > will > > probably be bid up. > > > > I just received one that I won. Seems to be working fine after a quick > > breadboard lashup. I'll be making an enclosure for it next. > > > > A little expensive IMO, but given the trouble getting the precision > > resistors to DIY with the LTZ1000A, probably worth it. > > > > Orin > > Orin, > > What do you intend doing with it? > > I was thinking about getting one of those, with a view to putting it > in a box with a couple of terminals to have something to compare with > my 6.5 digit 3457A. But what put me off is a lack of knowledge in > knowing how to convert a 3458A reference board into a boxed unit with > a known output voltage at the terminals. How would I avoid / control > thermal EMFs? > > I'd be interested to hear what your plans are for it, and how you > intend tackling those issues. > > Do you know what the difference in the reference is between a standard > 3458A (8 ppm) and the high stability option 002 (4 ppm) model? I'm > guessing the chips for the option 002 might be the top performing > ones. I wonder if there's any way to tell from your board if it came > from a standard 3458A or a 3458A with option 002. > > Dave > ___ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 3458A reference boards on ebay
- Original Message - From: "Dr. David Kirkby (Kirkby Microwave Ltd)" To: "Discussion of precise voltage measurement" Sent: Tuesday, January 27, 2015 2:24 AM Subject: Re: [volt-nuts] 3458A reference boards on ebay > On 27 January 2015 at 09:16, Orin Eman wrote: > > There is a seller letting a slow trickle of them out there... they seem to > > be going for about $165. The current batch of two is around $100, but will > > probably be bid up. > > > > I just received one that I won. Seems to be working fine after a quick > > breadboard lashup. I'll be making an enclosure for it next. > > > > A little expensive IMO, but given the trouble getting the precision > > resistors to DIY with the LTZ1000A, probably worth it. > > > > Orin > > Orin, > > What do you intend doing with it? > > I was thinking about getting one of those, with a view to putting it > in a box with a couple of terminals to have something to compare with > my 6.5 digit 3457A. But what put me off is a lack of knowledge in > knowing how to convert a 3458A reference board into a boxed unit with > a known output voltage at the terminals. How would I avoid / control > thermal EMFs? > > I'd be interested to hear what your plans are for it, and how you > intend tackling those issues. > > Do you know what the difference in the reference is between a standard > 3458A (8 ppm) and the high stability option 002 (4 ppm) model? I'm > guessing the chips for the option 002 might be the top performing > ones. I wonder if there's any way to tell from your board if it came > from a standard 3458A or a 3458A with option 002. > > Dave Dave: The 002 reference boards have another label on them marked 03458-66519 which overlays the etched number on the PC board. As a matter of fact see the new listing on evilbay 271754789913. The super ultra stable 2ppm is marked 03458-66529 to the best of my knowledge. Bill > ___ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] 3458A reference boards on ebay
I forgot to mention, that these original hp reference are a bargain for around 100$. LTZ1000 /A cost 35.. 55$, 3 PWW or MBF for 10..20$ each, plus the additional stuff. They only need a thermal shield around the LTZ1000A on component and solder side, the pimping to 55°C (by 100k PWW in parallel to the 15k BMF), a shielding, and a PSU. The circuit is the same as in the LT datasheet, that's totally sufficient for stability. And it's very compact, easing the shielding. No fancy slots or other gimmicks for the PCN and components.. The stability is determined mainly by the LTZ1000 and its oven temperature. Therefore, that's a recommendation. FRank ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] 3458A reference boards on ebay
Hello fellow-nuts, do you already know about our monster discussion on DIY LTZ1000s on EEVBLOG? http://www.eevblog.com/forum/projects/ultra-precision-reference-ltz1000/msg180731/#msg180731 There are several people who have successfully assembled such boards, and they are pretty stable, much more stable than the HP ones, and the precision resistors are also easy to obtain, if you use precision wire-wound, which are at least as good as the bulk metal foil, for this purpose. The 002 reference is the same as the standard one, but is selected for lower drift.. assuming these run 24/365. Otherwise, the may show big hysteresis and have to re-initialized for a period of time, to reach the same level of stability. standard boards are rumored to achieve the same level of stability after some years, also. In DIY designs, but also in these HP references, simply reduce the oven temperature to 55°C for the LTZ1000A, and to 45°C for the LTZ1000. That will typically improve their stability by a factor of 2 for each reduction of 10°C, compared to the about 95°C, the original HP reference inside the 3458A is running (due to max. environmental temperature spec.) To use these boards externally, simply put a metal shield around, give it a good ground, and a quiet, linear regulator (12V or so), and you're done. Once measured, you get an extremely stable (t & T) 7,1xV reference. Amplifying to 10V by a ChopAmp will require precision resistors, which will account most for the annual drift, then. If you really need that, use oil filled hermetically sealed Vishay types, e.g. VHP202Z. They really drift < 2ppm/ 6 years, and may have very low T.C. (dR / dT, physically correctly measured). Or you may build a 2 stage PWM for that purpose. Then you only need a precise ratio standard, to transfer the (known) 7,1xV to 10V.. a 34401A will probably do the job for < 1ppm accuracy. More details in the mentioned thread; my description in 5 or 6 chapters you may find on pages 12-16. Frank ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 3458A reference boards on ebay
On 27 January 2015 at 09:16, Orin Eman wrote: > There is a seller letting a slow trickle of them out there... they seem to > be going for about $165. The current batch of two is around $100, but will > probably be bid up. > > I just received one that I won. Seems to be working fine after a quick > breadboard lashup. I'll be making an enclosure for it next. > > A little expensive IMO, but given the trouble getting the precision > resistors to DIY with the LTZ1000A, probably worth it. > > Orin Orin, What do you intend doing with it? I was thinking about getting one of those, with a view to putting it in a box with a couple of terminals to have something to compare with my 6.5 digit 3457A. But what put me off is a lack of knowledge in knowing how to convert a 3458A reference board into a boxed unit with a known output voltage at the terminals. How would I avoid / control thermal EMFs? I'd be interested to hear what your plans are for it, and how you intend tackling those issues. Do you know what the difference in the reference is between a standard 3458A (8 ppm) and the high stability option 002 (4 ppm) model? I'm guessing the chips for the option 002 might be the top performing ones. I wonder if there's any way to tell from your board if it came from a standard 3458A or a 3458A with option 002. Dave ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
[volt-nuts] 3458A reference boards on ebay
There is a seller letting a slow trickle of them out there... they seem to be going for about $165. The current batch of two is around $100, but will probably be bid up. I just received one that I won. Seems to be working fine after a quick breadboard lashup. I'll be making an enclosure for it next. A little expensive IMO, but given the trouble getting the precision resistors to DIY with the LTZ1000A, probably worth it. Orin ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
