Wet bulb vs digital hygrometer conversion help.

[kartking22]

I have a vintage redwood cabinet style incubator. It came with the original thermometer and the wet bulb hygrometer. I just recently purchased a digital thermometer/hygrometer to be more acurate in my settings but I don't have the conversion from one to the other. Wet bulb temperature is supposed to be 88-90 degrees on the hygrometer. What is the actual humidity supposed to be digitally?

 

[Ruditchka]

Here is conversion link/chart: http://www.poultryconnection.com/quackers/chart.html

 

[Ruditchka]

Looks like 62-68% would be 88-90 on a wet bulb with incubator temp set at 100degrees.(Changes w/temp farenheit change)