Hi all and thanks for your replies. I should explain my objective and reason for constructing an ADR1399 based voltage reference.
My "best" DMM is an ancient Fluke 8050A and I wanted to check the calibration of this device. I need to be able to measure down to 100s of uV which this meter will not do, but I wanted to ensure I was ballpark in the mV range.
I construct Eurorack synthesiser modules which use the 1V/octave system for voltage to pitch i.e. note C0 = 0v, C1 - 1.0v etc. Each octave is divided into 12 semitones and each semitone is a 0.0833V increment.
Mouser sent a product announcement for the SMT version of the ADR1399 so I investigated and purchased the through hole version naively thinking that if I built the circuit in the datasheet adjusting my shunt value to ensure 3mA for the Zener, 7.05 volts would be present at the reference output and I could gain a degree of confidence in my meter calibration at least down to the mV range.
Before cominng here I did experiment with different shunt values to swing from <3mA up to 5mA and also varied my supply voltage etc and always seeing 6.920V.
I now know that my voltage reference build is fine and is accurate and stable at 6.920 instead of 7.050V
![Smiley :)](https://www.eevblog.com/forum/Smileys/default/smiley.gif)
Thanks again for taking the time to look at my naive newbie experiments, I will most likely purchase a new DMM that gets me into the uV range.
Thanks
Sean