Electronics > Metrology

Most stable VPG parts, HZ or VHP?

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I'm aware you have to read between the lines with VPG datasheets and the real world performance may differ from the implied specs.  When comparing the VPG HZ vs VHP which tend to have the lowest real world TCR and Self Life stability?  Curious if anyone has any real experience between them.  I know the HZ series is used on some secondary resistance standards, but it almost seems as if the VHP101,VHP103,VHP203 may perform even better (at least looking at the datasheets).  The advantage of the HZ parts seems to be higher power with larger packages using multiple elements and the option for 4 wire leads.  Maybe the multiple elements in the VHAxZ series (eg VHA518-10Z) could be an advantage and offer some additional averaging to stabilize the overall part?  Thoughts or experience?

I like my two VHA518's. Price of those is also VERY different to VHP1xx/2xx :) Both of VHA518's I tested and published in my TCR database article before.

Thanks Illya, I just read over your TC article.  It seems the VHP101's you tested all showed a slightly better TC than the VHA518's. Just for fun, I'm going to call Texas Components tomorrow and get a quote for a few options.

It's also interesting to note that the VHZ,VPG, VHP203 etc. specs state typical shelf life stability of 2ppm for at least 6 years, whereas the VH series specify maximum drifts of 5ppm for 1 year and 10ppm for 3 years.

So which is the better spec? Do they have similar drifts in practice? :-//

[EDIT: Changed 3ppm to 5ppm]

HZ series wins in the stability department for reference purposes.

VH series has shelf life of 5ppm after 1yr and 10ppm after 3yr, while the VHP and HZ series both have shelf life of 2ppm after 6 years.

Now, if your looking at stability at rated power this is where HZ partly shines over VHP.  HZ is rated at 20 ppm / 2000 hrs at rated power (0.3W+ at 25C) while the VHP is rated at 50 ppm / 2000 hrs at rated power (0.3W at 70C). 

I often wonder if they are the same resistors but catered to different applications, hence the different operating temperature specifications


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