Mini Metrology Kit for travelling - advice sought

[enut11]

This one looks promising. Has anyone tried it?
Ebay item: 388649447777

[tatel]

Looks like Tony Albus tried something quite similar, but supposedly it was calibrated with a 7.5d device...

[enut11]

Thanks @tatel. I will check that out.
The ebay seller I contacted did not offer a calibration certificate making his item useless.
Another ebay 399 reference I saw with SMA output offered calibrated 2.5, 5.0, 7.5 and 10.0v but no direct zener output.

[KungFuJosh]

Thanks @Tate. I will check that out.
The ebay seller I contacted did not offer a calibration certificate making his item useless.
Another ebay 399 reference I saw with SMA output offered calibrated 2.5, 5.0, 7.5 and 10.0v but no direct zener output.

Why is it useless without the cert? If they did include a certificate, would you blindly believe it to be authentic?

If you need an absolute value to be accurate, it needs a valid & traceable certificate, which you will not find for any of those.

I have the VREF10-001r9, and I think it's quite good for a portable reference, and comes with a real certificate. You can see results from it in the Noise/Stability thread. It's not as good as a good ADR1399 ref, but it's excellent for what it is.

[Smokey]

You can use the the best in cal meter to "certify" one of these ebay toys, but it is almost guaranteed to have a terrible Tc and age and drift all over the place even at constant temp.   If you are interested in "metrology" you should stop expecting small cheap portable stuff you get off ebay for $5 to also be high quality and reliable.

[enut11]

KungFuJosh
Why is it useless without the cert? If they did include a certificate, would you blindly believe it to be authentic?

If you need an absolute value to be accurate, it needs a valid & traceable certificate, which you will not find for any of those.

I have the VREF10-001r9, and I think it's quite good for a portable reference, and comes with a real certificate. You can see results from it in the Noise/Stability thread. It's not as good as a good ADR1399 ref, but it's excellent for what it is.
[/quote]

@KungFuJosh, are you talking about a chip or complete 10v reference? My search so far indicates that the chip is not available.
I need a calibrated reference because I am nowhere near where I could get one calibrated.
enut11

[KungFuJosh]

@KungFuJosh, are you talking about a chip or complete 10v reference? My search so far indicates that the chip is not available.
I need a calibrated reference because I am nowhere near where I could get one calibrated.
enut11

I'm not sure what chip you can't get, but I'd recommend a real calibrated reference first either way.

This is something you should consider: https://voltagestandard.com/shop/ols/products/vref10-001-r9

If it says out of stock, email him and let him know you want one.

[enut11]

@KungFuJosh
That was the website that cannot supply their best reference due to chip unavailability.

I have lots of good Vrefs in my home lab including an LTZ1000 but we are away on an extended caravanning holiday.
enut11

[KungFuJosh]

Oh, that sucks. I hope he makes a new version with a newer/better chip then.

[enut11]

I was asked what possible use is a calibrated voltage reference in a caravan?

The short answer is none...

However, an uncalibrated reference is useless now or later.

[KungFuJosh]

However, an uncalibrated reference is useless now or later.

Unless you get it calibrated now or later.

[Doctorandus_P]

I don't agree here. You don't necessarily need "metrology grade" equipment to do metrology things and make it do something useful. For example, you can have a few "decent" voltage reference IC's, build a setup with an uC, a few (74hc)4051 chips and a whole bunch of TL431 chips (They are available from a lot of brands, some claim much better stability then others), and then build a rig that logs and compares long term stability / drift of the 431 class IC's.

[enut11]

Chinese LM399 reference has arrived. I let it run overnight before testing.

As received Agilent 34410A cal data as follows:
10v  9.94401
Vz    7.00681

My Fluke 4.5D 8060A reads:
9.944v
7.007v

Encouraging but inconclusive.
Today it goes to a Forum member who can verify this.