Heathkit Model IM-103
Line Voltage Monitor
Calibration Procedure
· With the meter off, the meter pointer should be over the 90 volt indication on the meter face. If it is not, turn the mechanical zero-adjust screw at the bottom of the meter until the pointer is properly aligned
Ancillary Equipment Needed
AC VTVM (optional)
Variable AC voltage Source (optional)
* * * * * * *
INITIAL ADJUSTMENTS
( ) Set the HI and LOW controls at the center of their rotation.
( ) Set the NORM-CAL switch in the CAL position.
ADJUSTMENT WITHOUT INSTRUMENTS
( ) Connect the instrument to the AC line.
( ) Adjust the LOW control to indicate 137.5 VAC.
( ) Set the NORM-CAL switch to NORN.
· To complete the following steps it is necessary to know the correct AC line voltage. If you do not know the correct power line voltage, do not perform this step.
( ) Adjust the HI control to indicate the voltage of the AC line being measured.
( ) Calibration procedure is complete.
ADJUSTMENT WITH INSTRUMENTS
· A variable AC voltage source and an accurately calibrated AC voltmeter are required for the following steps.
( )* Adjust the LOW control for a meter reading of 95 VAC.
( )* Set the output from the variable supply to 125 VAC.
( )* Adjust the HI control for a meter reading of 135 VAC.
( ) Repeat the above three marked steps* until the voltage monitor reads the same as the AC VTVM at 95 VAC and 135 VAC.
( ) Calibration procedure is complete.