At the moment, we don't do long period temperature curves on resistances, which I also want to start providing to our customers
I more meant that customer himself does "pre-test" before sending the box to you, and you just run it for few days (let box rest day 1, take 10 samples day 2, 10 other samples day 3, send unit back day 4, etc). Not necessary to have 24/7 longterm logging for calibration, you should expect already characterized reference at inbound. It's not the calibration lab job to do testing for the user, when asked (and paid for) only for calibration, which is measurement only, by the books. Hope this clarify things a bit, so we on same page.
As far as international shipping... I don't see that being much of a problem as long as you, the customer, is willing to pay for international shipping!
They'd better pay
![Evil >:D](https://www.eevblog.com/forum/Smileys/default/xevil.gif.pagespeed.ic.tdrs7Uj5gu.png)
. That sounds right, no problems. I just had different experience few years ago, when asked some cal labs to do same thing, with me paying shipping both ways, when I was looking to import DCV/Ohm into my homelab. I hand-carried standards and did own transfers since then, so it's less of an issue for me now, but I'd be looking for 3rd callab cross-check, and your service seem to fit great into the spot.
TiN, I've not seen any of these LTZ boxes you speak of... they sound pretty sweet! I would love to give them a go... and you say they have a 9pin DSub connector to plug into a F732B?
Well, the box I'm talking right now is not that refined, but I see no difficulty to prepare above-mentioned in Q3'2017 timeframe to perform a transfer. Since 2014 I was tinkering and had designed, built and tested compact 7V LTZ1000-based module following standard datasheet application almost exactly, and using bank of 4 modules as my homelab primary DCV standard, doing cross-checks from time to time. Design is fully open-hardware and covered
in article on my site. One of latest modules was also tested in more detail
covered here and
discussed here and even got group of voltnuts to fab PCBs
![Smiley :)](https://www.eevblog.com/forum/Smileys/default/xsmiley.gif.pagespeed.ic.R8GFI-pF6f.png)
. For
my first transfer in March'16 I've used standalone 3458A's A9 module to calibrate my first 3458A after repair. That got me to DCV within 6 ppm, which later in August was improved to <2ppm with bank of 8 x LTZ1000's (6 on my modules, 2 inside K2002's). For Ohms I use aged Vishay hermetic foils so far.
As of power port, it's easy to design in the enclosure to fit my references and provide DB9 interface, which can couple to 732B-7001 battery pack/charger. so you don't have to worry about finding power supply to power up the reference. International shipping is usually too long to have unit sent hot, and shipping large batteries require special permits/legalpapers anyway. So I'll have to test for hysteresis and stability after thermal shock first, before I have anything shipped. Surely other option to have regular mains PSU integrated as well, but that adds weight and size.
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If you would like to discuss further, either on here or over email, don't hesitate to get ahold of me
Thanks for being transparent for hobby level things, this is
rare thing in metrology market. We can keep discussion here for time being, as things covered are pretty generic. You will get line of voltnuts lineup with their boxes quicker than you realize