YJ108 DC millivolt source is a DC voltage source used for calibrating various high input impedance parameter display instruments and temperature control instruments of DDZ III type with thermocouples or DC voltage inputs. Due to the internal resistance of around 20 Ω in the mV range, it is not suitable for calibrating different dynamic coil instruments.

This product also has two sets of digital dial settings for "left" and "right", which can provide V or mV values. In conjunction with the thermocouple selection switch, select the S, R, K, T, J, and E thermocouple types that comply with IEC and national standards to provide the set thermocouple simulation potential value at a certain temperature that can automatically deduct the cold junction potential.
This product also has selection switches for the "left" and "right" digital dials, as well as an output "zero" switch. These two switches are used to perform three-point calibration (zero, midpoint, and full degree) on the calibrated instrument.