I got out my old 890 and was going to use it on a balance job and realized I had forgot what the difference is between MIL High and MIL Low. What is the difference? Which do you use? Why is the MIL low amplitude about ten times higher than MIL hogh at 650 CPM?

Thanks

Mike,
I know nothing about the 890 but I do know we have some handheld IRD,s around here with analog meter that have a high and low mils. I don't have one handy but the difference is a filter for high or low frequency. I think the cutoff was somewhere around 650 rpm.

From the IRD 890 Manual.
Collecting Phase Data using a displacement sensor. If not within the correct speed range for phase analysis a "BANDWIDTH ERROR" message will be displayed.
The following lists the valid speed range for displacement.
Measurement Unit MILS,L RPM RANGE = <30 Hz
Measurement Unit MILS,H RPM Range = 20-100 Hz

Hope this helps.