Yellow springs instrumnets ysi 31 conductivity bridge

Yellow springs instrumnets ysi 31 conductivity bridge

The YSI Model 31 is a laboratory instrument designed for precise direct measurement of electrical resistance or conductance.
Unit powers on and ligts up the light dims and brightens when sensitivity control knob is turned. I believe this unit to be in good working order. This unit does NOT come with any manuals or accessories. Everything that is included is shown in the pictures.
Range, 0.2 ohms to 2.5 megohms; 0.2 micromhos to 2.5 mhos
Accuracy, +/- 1% of reading from 2.0 ohms to 2.0 megohms, and from 2.0 mictomhos to 2.0 mhos. Accuracy decreases outside these ranges
Resolution, 0.5% or better, except x 100,000 micromhos and x 1 ohm which have a 1% resolution
Indicator, EM84/6FG6 high intensity electron ray tube
Bridge supply, Line frequency of 1 KHz selected by front panel switch
Ambient [temperature] range, 0 to 50°C at rated accuracy
Below is the link to the user guide LINK