Perhaps interesting dataset for somebody curious about how freshly built LTZ ref behave when first powered on, and how initial days of settle look like.
![](https://xdevs.com/doc/xDevs.com/FX/build10/ltzf_nov18_1.png)
Four meters used for sampling:
* 3458A with Keithley 7168 nV-scanner card (ch1-ch8)
* 3458A (drifty ADC) on black HPC chart.
* K2002 (K4 chart)
* second K2002 (K6 chart) measuring my 24/7 792X as main 10V reference (LTZ FX based)
No aircon, so bit higher ambient temps than usual 24c
From November 7 I restart logging, and ran ACAL DCV on 3458A drifty. You can see it's ADC drift on first 2 days as ~+2ppm a day.
But to my great surprise drift on ADC become <0.1ppm a day afterwards. I'm running multiple ACALs now every day. CAL72? value also show similar data.
I don't believe in self-fixing 3458 ADCs, but never know. Meter was left running for about a month, drifting.