With the leads hanging in the air, being unterminated, it is normal
that the instrument will pick up some voltage, or AC radiation from the
surrounding environment, such as from the wiring in the walls, and etc.
The 200 mv scale is very sensitive.

The proper way to test this is if the leads are shorted, and the meter
zeros, indicates that the meter is able to be referenced.

The second part of the basic test is to have a known proper calibrated
AC voltage source that is in the 200 mv range, to see if the meter is
accurate.

Jerry G.
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