Look at eBay voltage ref (AD584KH) measured with UT71D and 3478A

[AlessandroAU]

Hi everyone, I bought this voltage reference from eBay and wanted to share with you some measurements with my UT71D and 3478a. The reference comes with calibration values from an Aglient 34401A recorded on a sticker on the back of the unit.

This is the unit: http://www.ebay.com.au/itm/391177355684?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Here's the output as measured on my UT71D and 3478a, the table shows the raw values and well as the percentage error. Compared to the reference the UT71D has an average error of 0.07% and the 3478a is about an order better at 0.009%

[tszaboo]

Wow, and that is a 15 ppm class reference voltage "calibrated" with a 34401A.
I had in mind a 3PPM reference voltage calibrated with a 3458A, but I cancelled it, because I deemed it less accurate than I wanted, and I could only organize a single 1000 NPLC measurement (after heat-up) with it. Now I wonder if I should do it after all.
May I asked, why did you buy this reference, and would you consider buying a new one? [/marketing mode]

[Lightages]

From your measurements, the UT71D is still within specification. This is assuming that the reference is at the measured value from the seller. I also have two of these references and I think they are great value. I will buy more. They are cheaper than the price of shipping of the references I have from voltagestandard.com for adjustment.

[McBryce]

I bought one of these a while back. I only wanted it to know that my meters are somewhat within spec. My Keithley 2000 (Last calibration in March 2014) came in at 0.003%, so either it's extremely accurate or the device (or the calibration 34401) is also off

I think I paid €16 for it. At that price it's definitely worth it (assuming it is accurate).

McBryce.

[AlessandroAU]

Wow, and that is a 15 ppm class reference voltage "calibrated" with a 34401A.
I had in mind a 3PPM reference voltage calibrated with a 3458A, but I cancelled it, because I deemed it less accurate than I wanted, and I could only organize a single 1000 NPLC measurement (after heat-up) with it. Now I wonder if I should do it after all.
May I asked, why did you buy this reference, and would you consider buying a new one? [/marketing mode]

I just wanted wanted to confirm that my instruments were somewhat accurate. I'm not sure if I would buy another, do you have a suggestion as to what would be the step up from this reference?

[tszaboo]

Wow, and that is a 15 ppm class reference voltage "calibrated" with a 34401A.
I had in mind a 3PPM reference voltage calibrated with a 3458A, but I cancelled it, because I deemed it less accurate than I wanted, and I could only organize a single 1000 NPLC measurement (after heat-up) with it. Now I wonder if I should do it after all.
May I asked, why did you buy this reference, and would you consider buying a new one? [/marketing mode]

I just wanted wanted to confirm that my instruments were somewhat accurate. I'm not sure if I would buy another, do you have a suggestion as to what would be the step up from this reference?

I've been considering for some time to design a reference voltage board, and sell it in small quantities. I think it could have a tempco of 3ppm, trimmed and calibrated voltage of 10V, calibration with a 3458A. but I always put the project aside. Now I'm wondering if I should do it.

[tszaboo]

Wow, and that is a 15 ppm class reference voltage "calibrated" with a 34401A.
I had in mind a 3PPM reference voltage calibrated with a 3458A, but I cancelled it, because I deemed it less accurate than I wanted, and I could only organize a single 1000 NPLC measurement (after heat-up) with it. Now I wonder if I should do it after all.
May I asked, why did you buy this reference, and would you consider buying a new one? [/marketing mode]

I just wanted wanted to confirm that my instruments were somewhat accurate. I'm not sure if I would buy another, do you have a suggestion as to what would be the step up from this reference?

i would say, try to make your own LM399 ref? there is so much tech tips from the pros threads inside here. but it will need tons of data gathering from components going to be used. just look at all that data from characterisation of precision resistors (the TC thread?).

in doing so, there is a ton of things to learn, and i think it is worth the journey if time permits

The LM399 is a 2% initial accuracy reference voltage, which is a few PPM stable.
The OP wanted a reference voltage which is calibrated to about 100ppm, while the stability is like 50ppm in normal conditions.
Apples and oranges.

[Lightages]

A step up would be the references sold at www.voltagestandard.com

[ralphrmartin]

This appears a little more accurate, at a slightly higher price, using the AD588

http://www.ebay.co.uk/itm/AD588-High-Precision-Voltage-Reference-Module-Multiple-Output-AD588BQ-1-5-ppm-C-/171826997772?hash=item2801afea0c

[kubatyszko]

This appears a little more accurate, at a slightly higher price, using the AD588

http://www.ebay.co.uk/itm/AD588-High-Precision-Voltage-Reference-Module-Multiple-Output-AD588BQ-1-5-ppm-C-/171826997772?hash=item2801afea0c

Warning about this seller, I did buy one, but it did not come with ANY of the promised readings supplied - I contacted the seller and he had no idea what I was asking for. I negotiated a refund and we parted ways.
If you have some equipment to get actual readings of this unit - it's a good buy, but if you want the readings, go for the one OP has bought (I have one too, came with the readings).

[ralphrmartin]

Warning about this seller, I did buy one, but it did not come with ANY of the promised readings supplied - I contacted the seller and he had no idea what I was asking for. I negotiated a refund and we parted ways.
If you have some equipment to get actual readings of this unit - it's a good buy, but if you want the readings, go for the one OP has bought (I have one too, came with the readings).

Thanks. Actually, it seems to originally come from here:
http://world.taobao.com/item/43264515923.htm
and the eBay guy is just a reseller. Anyway, I'll get one next time I am in China, and see if it does come with the calibration data promised.

[TiN]

but I always put the project aside. Now I'm wondering if I should do it.

Likely right thing. I was trying to sell two reference modules (on high-end scale tho, LTZ-based, with proper parts) for a BOM-cost+shipping, managed to sell just only one after few months to one of members here. That's was it for me on selling reference devices.

P.S. I made them for own use/learning mainly, so going to market was never a goal.