@Andreas,
I will try and answer your questions.
The setup used. Most devices are socketed in the fixture pictured in the attachment. I built this fixture to test and age devices for use later in various projects, so I used sockets. Note the VRE305 socket is a high quality mil-max socket, the others are standard 8 pin sockets from digikey.
A few devices are in various reference boxes such as the one marked on the 10V chart as "PTC AD587UQ" This device is thermally stabilized with a PTC thermistor as an experiment.
A list of the devices not in the fixture follows.
10V REF01EP-1 is socketed and housed in a project box.
10V PTC AS587UQ is socketed and thermally stabilized using a PTC thermistor.
10V AD587UQ-1-HP is socketed and housed in a aluminum "hotbox" which is maintained at 52C via a PWM heater servo.
10V MV-106...this is my EDC voltage standard and really doesn't belong on this chart but appears for reference
10V LM399 is soldered into a voltage reference circuit in a project box.
5V LT1460GCZ5-1 is soldered and housed in a project box (same box as REF01EP-1) I suspect that some of the noise on the other LT1460 devices is from the sockets used.
VRE305. I returned the first VRE305 because it was clearly out of spec for initial voltage output and it looked like it was also drifting much more than spec. After submitting my data to APEX they agreed to ship me a new one if I returned the old one. We each paid for shipping...me to return and APEX to send me a new one (FedEx no less). The new unit is working much better than the original. A friend of mine who has extensive experience with the VRE305 says that the units made by APEX are not so good anymore. The original units (can't remember original manufacturer) were much better. These chips are pricey...more than LTZ1000. I don't recommend them.
My DMM is an HP34401A which for this voltage and range setting is specified at 6uV/degC maximum. I suspect the real value is somewhat lower than that.
The data is in an Excel file which can be exported to CSV ore TXT. PM me and I'll send you whatever format you perfer via private email.
Insatman