Heathkit Model IB-1B

Impedance Bridge

Calibration Procedure

· The meter pointer should be centered on the meter scale.  If the pointer is not over this mark, adjust the zero-adjust screw at the bottom of the meter until the pointer is properly aligned.

· Install a fresh 6-volt battery into the unit.

Ancillary Equipment Needed

1000-ohm 1% resistor

· Mount the 1% resistor on a dual banana plug to use as a calibration standard.

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Front Panel Initial Conditions

(    )         Set the SELECTOR switch [top left] to the R position.

(    )         Set the MULTIPLIER switch [top right] to the 1K ohms position.

(    )         Set the DETECTOR switch to the shunted galv position.

(    )         Set the GENERATOR switch to the DC position.

(    )         Connect a 1000-ohm 1% resistor to the “R” (resistor) terminals [top left terminals].

(    )         Adjust the CRL control until the galvanometer nulls or at the zero position

(    )         Set the DETECTOR switch to the galv position.

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RESISTANCE SCALE CALIBRATION

(    )         Loosen the CRL knob carefully, checking to see that the null has not been disturbed.

(    )         Set the CRL pointer indicator exactly on 1.

(    )         Retighten the CRL knob carefully, checking to see that the null has not been disturbed.

(    )         Set the DETECTOR switch to shunted galv position.

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”D” AND “Q” SCALES CALIBRATION

· The “D” and “Q” scales will be reasonable accurate by placing the pointers on zero at the maximum counter-clockwise rotation. However, if maximum accuracy is desired, these controls may be set with the resistance section of the bridge.  Otherwise, proceed to the FINAL ADJUSTMENTS section.

(    )         Set the switches and controls as described in the Front Panel Initial Conditions section.

(    )         Connect the “R” terminals to the “L” terminals [top right terminals] using heavy gauge short leads and leaving the 1000-ohm 1% resistor across the “R” terminals.

(    )         Set the CRL pointer indicator exactly on 1.

(    )         Loosen the D knob carefully, checking to see that the null has not been disturbed.

(    )         Set the D pointer indicator exactly on 5.

(    )         Retighten the D knob carefully, checking to see that the null has not been disturbed.

(    )         Loosen the D – Q knob carefully, checking to see that the null has not been disturbed.

(    )         Set the D – Q pointer indicator exactly on 5.

(    )         Retighten the D - Q knob carefully, checking to see that the null has not been disturbed.

(    )         Loosen the Q knob carefully, checking to see that the null has not been disturbed.

(    )         Set the Q pointer indicator exactly on 50.

(    )         Retighten the Q knob carefully, checking to see that the null has not been disturbed.

(    )         Disconnect the heavy gauge jumper leads between the “R” terminals and the “L” terminals.

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FINAL ADJUSTMENTS

(    )         Set the DETECTOR switch to shunted galv position.

(    )         Disconnect the 1000-ohm 1% resistor from the “R” terminals.

(    )         Calibration procedure is complete.