Re: [volt-nuts] [Bulk] Re: 3458A reference boards on ebay
The reference module is in a metal box and uses an external linear PS with internal separate regulation. I don't think its external EMI, but anything is possible. Randy On Wed, Jan 28, 2015 at 10:28 PM, Hendrik Dietrich don_he...@gmx.de wrote: Am 29.01.2015 04:07, schrieb Randy Evans: I bought two HP-3458A ref boards from John Daly (he no longer has any more) and they worked fine but have intermittent noise bursts. I suspect they were rejects from HP/Agilent. At some point I will probably replace the LTZ1000As and reduce the internal temperature set point for better stability. Has anyone else had any issues with these units? BTW, I packaged the units in an enclosure for a stand-alone reference and, except for the occasional noise bursts, seem very stable according to my HP 3458A and fluke 732A/ESI RV722 KVD. Randy Hi Randy, Noise bursts, especially if they get back on track again, sound like electromagnetic interference from your short description. If applicable, turn of the CFL or LED lighting, replace the switch-mode power supply with a linear one or even better a battery,, try a known non-reject in place of the ebay reference module, spread some capacitors on/around the module and/or invest in a metal box. 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] [Bulk] Re: 3458A reference boards on ebay
Well, sounds like you already prepared against some of my suggestions. Still there are possibilities to troubleshoot it - i cannot neither see that you checked everything I listed nor that my list is complete and you had much bigger ideas. The datasheet gives some figures telling how much some influences, like R variations (and as a result I variations) get supressed on the output - I would go hunting for nodes where the noise bursts are biggest if all preventive actions failed. Up to a certain point, troubleshooting is fun. Hendrik Am 29.01.2015 18:22, schrieb Randy Evans: The reference module is in a metal box and uses an external linear PS with internal separate regulation. I don't think its external EMI, but anything is possible. Randy On Wed, Jan 28, 2015 at 10:28 PM, Hendrik Dietrich don_he...@gmx.de wrote: Am 29.01.2015 04:07, schrieb Randy Evans: I bought two HP-3458A ref boards from John Daly (he no longer has any more) and they worked fine but have intermittent noise bursts. I suspect they were rejects from HP/Agilent. At some point I will probably replace the LTZ1000As and reduce the internal temperature set point for better stability. Has anyone else had any issues with these units? BTW, I packaged the units in an enclosure for a stand-alone reference and, except for the occasional noise bursts, seem very stable according to my HP 3458A and fluke 732A/ESI RV722 KVD. Randy Hi Randy, Noise bursts, especially if they get back on track again, sound like electromagnetic interference from your short description. If applicable, turn of the CFL or LED lighting, replace the switch-mode power supply with a linear one or even better a battery, try a known non-reject in place of the ebay reference module, spread some capacitors on/around the module and/or invest in a metal box. 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. ___ 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] [Bulk] Re: 3458A reference boards on ebay
I bought two HP-3458A ref boards from John Daly (he no longer has any more) and they worked fine but have intermittent noise bursts. I suspect they were rejects from HP/Agilent. At some point I will probably replace the LTZ1000As and reduce the internal temperature set point for better stability. Has anyone else had any issues with these units? BTW, I packaged the units in an enclosure for a stand-alone reference and, except for the occasional noise bursts, seem very stable according to my HP 3458A and fluke 732A/ESI RV722 KVD. Randy On Wed, Jan 28, 2015 at 9:40 AM, John Phillips john.philli...@gmail.com wrote: There is a bottom cover under the board. On Tue, Jan 27, 2015 at 9:01 PM, J. L. Trantham jlt...@att.net wrote: When these boards are installed in a 3458A, the LTZ1000 is covered by a small, white, 'hat' that mounts with screws that pass through the two holes on opposite sides of the LTZ1000. I've never removed the board to see if there is anything on the bottom of the board that would cover the bottom of the LTZ1000. Does anyone know what this 'hat' is constructed of or the HP/Agilent/Keysight part number of this item is? Is it available from Keysight? In the 3458A the reference board is under a cover that covers about half of the top of the meter but not 'insulated' beyond that, except for the 'hat' referred to above. It would appear desirable to find what that 'hat' is and see if something could be fabricated to 'insulate' the LTZ1000 for a 'do it yourself' standalone reference. Would appreciate hearing anything about how the reference board is 'insulated' in the 3458A. Thanks. Joe -Original Message- From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of Orin Eman Sent: Tuesday, January 27, 2015 11:45 AM To: Discussion of precise voltage measurement Subject: [Bulk] 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 orin.e...@gmail.com wrote: There is a seller letting a slow trickle of them out there... they seem to be going for about $165. The current batch of two is around $100, but will probably be bid up. I just received one that I won. Seems to be working fine after a quick breadboard lashup. I'll be making an enclosure for it next. A little expensive IMO, but given the trouble getting the precision resistors to DIY with the LTZ1000A, probably worth it. Orin Orin, What do you intend doing with it? I was thinking about getting one of those, with a view to putting it in a box with a couple of terminals to have something to compare with my 6.5 digit 3457A. But what put me off is a lack of knowledge in knowing how to convert a 3458A reference board into a boxed unit with a known output voltage at the terminals. How would I avoid / control thermal EMFs? I'd be interested to hear what your plans are for it, and how you intend tackling those issues. Do you know what the difference in the reference is between a standard 3458A (8 ppm) and the high stability option 002 (4 ppm) model? I'm guessing the chips for the option 002 might be the top performing
Re: [volt-nuts] [Bulk] Re: 3458A reference boards on ebay
Am 29.01.2015 04:07, schrieb Randy Evans: I bought two HP-3458A ref boards from John Daly (he no longer has any more) and they worked fine but have intermittent noise bursts. I suspect they were rejects from HP/Agilent. At some point I will probably replace the LTZ1000As and reduce the internal temperature set point for better stability. Has anyone else had any issues with these units? BTW, I packaged the units in an enclosure for a stand-alone reference and, except for the occasional noise bursts, seem very stable according to my HP 3458A and fluke 732A/ESI RV722 KVD. Randy Hi Randy, Noise bursts, especially if they get back on track again, sound like electromagnetic interference from your short description. If applicable, turn of the CFL or LED lighting, replace the switch-mode power supply with a linear one or even better a battery,, try a known non-reject in place of the ebay reference module, spread some capacitors on/around the module and/or invest in a metal box. 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] [Bulk] Re: 3458A reference boards on ebay
I think teletekj...@gmail.com has some that were removed from working unit to upgrade to the more stable board. On Wed, Jan 28, 2015 at 7:07 PM, Randy Evans randyevans2...@gmail.com wrote: I bought two HP-3458A ref boards from John Daly (he no longer has any more) and they worked fine but have intermittent noise bursts. I suspect they were rejects from HP/Agilent. At some point I will probably replace the LTZ1000As and reduce the internal temperature set point for better stability. Has anyone else had any issues with these units? BTW, I packaged the units in an enclosure for a stand-alone reference and, except for the occasional noise bursts, seem very stable according to my HP 3458A and fluke 732A/ESI RV722 KVD. Randy On Wed, Jan 28, 2015 at 9:40 AM, John Phillips john.philli...@gmail.com wrote: There is a bottom cover under the board. On Tue, Jan 27, 2015 at 9:01 PM, J. L. Trantham jlt...@att.net wrote: When these boards are installed in a 3458A, the LTZ1000 is covered by a small, white, 'hat' that mounts with screws that pass through the two holes on opposite sides of the LTZ1000. I've never removed the board to see if there is anything on the bottom of the board that would cover the bottom of the LTZ1000. Does anyone know what this 'hat' is constructed of or the HP/Agilent/Keysight part number of this item is? Is it available from Keysight? In the 3458A the reference board is under a cover that covers about half of the top of the meter but not 'insulated' beyond that, except for the 'hat' referred to above. It would appear desirable to find what that 'hat' is and see if something could be fabricated to 'insulate' the LTZ1000 for a 'do it yourself' standalone reference. Would appreciate hearing anything about how the reference board is 'insulated' in the 3458A. Thanks. Joe -Original Message- From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of Orin Eman Sent: Tuesday, January 27, 2015 11:45 AM To: Discussion of precise voltage measurement Subject: [Bulk] 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 orin.e...@gmail.com wrote: There is a seller letting a slow trickle of them out there... they seem to be going for about $165. The current batch of two is around $100, but will probably be bid up. I just received one that I won. Seems to be working fine after a quick breadboard lashup. I'll be making an enclosure for it next. A little expensive IMO, but given the trouble getting the precision resistors to DIY with the LTZ1000A, probably worth it. Orin Orin, What do you intend doing with it? I was thinking about getting one of those, with a view to putting it in a box with a couple of terminals to have something to compare with my 6.5 digit 3457A. But what put me off is a lack of knowledge in knowing how to convert a 3458A reference board into a boxed unit with a known output voltage at the terminals. How would I avoid / control thermal EMFs
Re: [volt-nuts] [Bulk] Re: 3458A reference boards on ebay
Well, the current supply isn't from John Daly as far as I know. My sanity check is monitoring the output of the 3458A reference board with an Agilent 34461A. I don't see any difference from when I was monitoring a Fluke 731B. So, I have no evidence either way. This 'monitoring' mostly shows the temp-co of the '61A which is in the order of 1ppm. I have started a new test with the '61A monitoring the ratio of the 731B to the 3458A reference. I'd prefer a differential test, but that doesn't work as well with the 3458A output at 7.17750V and the 731B at 10V. Orin. On Wed, Jan 28, 2015 at 7:07 PM, Randy Evans randyevans2...@gmail.com wrote: I bought two HP-3458A ref boards from John Daly (he no longer has any more) and they worked fine but have intermittent noise bursts. I suspect they were rejects from HP/Agilent. At some point I will probably replace the LTZ1000As and reduce the internal temperature set point for better stability. Has anyone else had any issues with these units? BTW, I packaged the units in an enclosure for a stand-alone reference and, except for the occasional noise bursts, seem very stable according to my HP 3458A and fluke 732A/ESI RV722 KVD. Randy On Wed, Jan 28, 2015 at 9:40 AM, John Phillips john.philli...@gmail.com wrote: There is a bottom cover under the board. On Tue, Jan 27, 2015 at 9:01 PM, J. L. Trantham jlt...@att.net wrote: When these boards are installed in a 3458A, the LTZ1000 is covered by a small, white, 'hat' that mounts with screws that pass through the two holes on opposite sides of the LTZ1000. I've never removed the board to see if there is anything on the bottom of the board that would cover the bottom of the LTZ1000. Does anyone know what this 'hat' is constructed of or the HP/Agilent/Keysight part number of this item is? Is it available from Keysight? In the 3458A the reference board is under a cover that covers about half of the top of the meter but not 'insulated' beyond that, except for the 'hat' referred to above. It would appear desirable to find what that 'hat' is and see if something could be fabricated to 'insulate' the LTZ1000 for a 'do it yourself' standalone reference. Would appreciate hearing anything about how the reference board is 'insulated' in the 3458A. Thanks. Joe -Original Message- From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of Orin Eman Sent: Tuesday, January 27, 2015 11:45 AM To: Discussion of precise voltage measurement Subject: [Bulk] 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 orin.e...@gmail.com wrote: There is a seller letting a slow trickle of them out there... they seem to be going for about $165. The current batch of two is around $100, but will probably be bid up. I just received one that I won. Seems to be working fine after a quick breadboard lashup. I'll be making an enclosure for it next. A little expensive IMO, but given the trouble getting the precision resistors to DIY with the LTZ1000A, probably worth
Re: [volt-nuts] [Bulk] Re: 3458A reference boards on ebay
There is a bottom cover under the board. On Tue, Jan 27, 2015 at 9:01 PM, J. L. Trantham jlt...@att.net wrote: When these boards are installed in a 3458A, the LTZ1000 is covered by a small, white, 'hat' that mounts with screws that pass through the two holes on opposite sides of the LTZ1000. I've never removed the board to see if there is anything on the bottom of the board that would cover the bottom of the LTZ1000. Does anyone know what this 'hat' is constructed of or the HP/Agilent/Keysight part number of this item is? Is it available from Keysight? In the 3458A the reference board is under a cover that covers about half of the top of the meter but not 'insulated' beyond that, except for the 'hat' referred to above. It would appear desirable to find what that 'hat' is and see if something could be fabricated to 'insulate' the LTZ1000 for a 'do it yourself' standalone reference. Would appreciate hearing anything about how the reference board is 'insulated' in the 3458A. Thanks. Joe -Original Message- From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of Orin Eman Sent: Tuesday, January 27, 2015 11:45 AM To: Discussion of precise voltage measurement Subject: [Bulk] 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 orin.e...@gmail.com wrote: There is a seller letting a slow trickle of them out there... they seem to be going for about $165. The current batch of two is around $100, but will probably be bid up. I just received one that I won. Seems to be working fine after a quick breadboard lashup. I'll be making an enclosure for it next. A little expensive IMO, but given the trouble getting the precision resistors to DIY with the LTZ1000A, probably worth it. Orin Orin, What do you intend doing with it? I was thinking about getting one of those, with a view to putting it in a box with a couple of terminals to have something to compare with my 6.5 digit 3457A. But what put me off is a lack of knowledge in knowing how to convert a 3458A reference board into a boxed unit with a known output voltage at the terminals. How would I avoid / control thermal EMFs? I'd be interested to hear what your plans are for it, and how you intend tackling those issues. Do you know what the difference in the reference is between a standard 3458A (8 ppm) and the high stability option 002 (4 ppm) model? I'm guessing the chips for the option 002 might be the top performing ones. I wonder if there's any way to tell from your board if it came from a standard 3458A or a 3458A with option 002. Dave ___ 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
Re: [volt-nuts] [Bulk] Re: 3458A reference boards on ebay
When these boards are installed in a 3458A, the LTZ1000 is covered by a small, white, 'hat' that mounts with screws that pass through the two holes on opposite sides of the LTZ1000. I've never removed the board to see if there is anything on the bottom of the board that would cover the bottom of the LTZ1000. Does anyone know what this 'hat' is constructed of or the HP/Agilent/Keysight part number of this item is? Is it available from Keysight? In the 3458A the reference board is under a cover that covers about half of the top of the meter but not 'insulated' beyond that, except for the 'hat' referred to above. It would appear desirable to find what that 'hat' is and see if something could be fabricated to 'insulate' the LTZ1000 for a 'do it yourself' standalone reference. Would appreciate hearing anything about how the reference board is 'insulated' in the 3458A. Thanks. Joe -Original Message- From: volt-nuts [mailto:volt-nuts-boun...@febo.com] On Behalf Of Orin Eman Sent: Tuesday, January 27, 2015 11:45 AM To: Discussion of precise voltage measurement Subject: [Bulk] 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 orin.e...@gmail.com wrote: There is a seller letting a slow trickle of them out there... they seem to be going for about $165. The current batch of two is around $100, but will probably be bid up. I just received one that I won. Seems to be working fine after a quick breadboard lashup. I'll be making an enclosure for it next. A little expensive IMO, but given the trouble getting the precision resistors to DIY with the LTZ1000A, probably worth it. Orin Orin, What do you intend doing with it? I was thinking about getting one of those, with a view to putting it in a box with a couple of terminals to have something to compare with my 6.5 digit 3457A. But what put me off is a lack of knowledge in knowing how to convert a 3458A reference board into a boxed unit with a known output voltage at the terminals. How would I avoid / control thermal EMFs? I'd be interested to hear what your plans are for it, and how you intend tackling those issues. Do you know what the difference in the reference is between a standard 3458A (8 ppm) and the high stability option 002 (4 ppm) model? I'm guessing the chips for the option 002 might be the top performing ones. I wonder if there's any way to tell from your board if it came from a standard 3458A or a 3458A with option 002. Dave ___ 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.
