Heathkit Model IP-28

1 – 30 VDC Regulated Power Supply

Calibration Procedure

· With the power supply off, the meter pointer should be over the zero indication on the meter face.  If it is not, adjust the mechanical zero-adjust screw at the bottom of the meter until the pointer is properly aligned.

Ancillary Equipment Required

470 ohm 2 watt resistor

* * * * * * *

NOTES

· Remove all jumper wires between the circuit grounds and chassis ground.

· Remove all loads from the supply terminals.

* * * * * * *

Front Panel Initial Conditions

(    )         Set the POWER switch to the OFF position.

(    )         Set the STANDBY switch to the STANDBY position.

(    )         Set the CURRENT control to maximum clockwise (10-turn).

(    )         Set the VOLTAGE control to maximum counter-clockwise.

(    )         Set the METER switch to the VOLTAGE position

(    )         Set the CURRENT RANGE switch to the 0.1 A position.

(    )         Set the VOLTAGE RANGE switch to the 30V position.

INITIAL ADJUSTMENTS

(    )         Set the HIGH CURRENT ADJ. control (W) [see PICTORIAL 2-7] to maximum counter-clockwise.

(    )         Set the POWER switch to the ON position.

(    )         Set the STANDBY switch to the DC ON position.

(    )         Adjust the VOLTAGE control until the meter reads 30 V.

(    )         Set the METER switch to the CURRENT position.

(    )         Set the CURRENT switch to the 1 A position.

(    )         Set the STANDBY switch to the STANDBY position.

(    )         Connect a wire between the + and – output terminals.

(    )         Set the STANDBY switch to the DC ON position.

(    )         Adjust the HIGH CURRENT ADJ. control (W) until the meter reads 1 ampere full scale.

(    )         Set the STANDBY switch to the STANDBY position.

(    )         Disconnect the wire between the + and – output terminals.

(    )         Set the STANDBY switch to the DC ON position.

OPERATIONAL ADJUSTMENTS

· Figures 5, 7, 8, and 9 depict voltage-current relationships.  Voltage is shown on the vertical scale and current is shown on the horizontal scale.

(    )         Adjust the VOLTAGE control until the meter reads 20 V.

(    )         Set the STANDBY switch to the STANDBY position.

(    )         Connect a 470 ohm 2 watts resistor to the output terminals.

(    )         Set the STANDBY switch to the DC ON position.

(    )         Adjust the CURRENT control counter-clockwise until the voltage just starts to decrease.

· For heavier loads (lower resistance) the current drain will be higher than the example and the limit could be set higher, or the output voltage will drop rapidly to a value appropriate for the current limit selected.

(    )         Adjust the VOLTAGE control clockwise.  The voltage should not increase.

· The Power Supply is now current limited.

(    )         Adjust the VOLTAGE control counter-clockwise until the meter reads less than 20 V.

(    )         Adjust the VOLTAGE control clockwise until the meter just reads 20 V.

(    )         Set the METER switch to the CURRENT position.  The Voltage panel lamp should go out and the amber CURRENT lamp should light.

(    )         Adjust the VOLTAGE control clockwise.  The current reading should not increase significantly.

(    )         Adjust the VOLTAGE control counter-clockwise.  The voltage and the current should decrease.

(    )         Alternate the METER switch between the CURRENT and VOLTAGE positions.

(    )         Set the STANDBY switch to the STANDBY position.

(    )         Set the POWER switch to the OFF position.

(    )         Disconnect the 470 ohm 2 watts resistor from the output terminals.

(    )         Calibration procedure is complete.