ACL MODEL #385
CALIBRATION INSTRUCTIONS

CALIBRATION

The checker should be calibrated on average every 12 months. A test resistance can be applied across the parallel bars to verify if the checker is within specification, using a resistance decade box. Calibration can be obtained by contacting your supplier.

SPECIFICATION

Power Supply: 9-volt PP3 alkaline battery
Test Voltage: Nominal 9 volts
Temperature Range:
       Operating 40º to 120º F (5º C to 49º C)
       Storage (-15º C to + 60º C)
Relative Humidity: 0% to 90% (non-condensing)
Resolution: One order of magnitude
Changeover Point: ½ decade on a logarithmic scale (3.16 x 10n)
Changeover Point Accuracy: ± ½ decade
Accuracy: ± 10% 
Repeatability: ± 5%
Weight: 6 ounces
Dimensions: 130mm x 70mm x 25mm

SURFACES RESISTANCE CHECKER CALIBRATION PROCEDURE

This product has been produced using 1% meta film resistors, and high speed OP-AMP Integrated circuits. The calibration procedure is based upon the product being of linear technology.

The changeover points are determined on resistance and are ± ½ decade on a logarithmic scale i.e. (3.16 x 10n). The linearity of the changeover points is ± 10 from the mean value per unit.

TEST EQUIPMENT USED

Resistance Decade Box
Test Leads

The resistance decade box required will need a range of from > 1 kilohm to 999 meg ohms or 10^9. Measurement greater than 10^9 are calculated using cad generated techniques, as high resistances greater than 109 are difficult to verify with a test voltage of 9 volts.

Connect the test leads from the resistance decade box to the test probes of the checker, set the decade box to the desired resistance i.e. 10^3 = 1 K, then press and hold the checker's test button, the 10^3 LED should light, 10 K 10^4 LED should light and so on. To measure the changeover point between decades, increase the resistance of the decade box while pressing the checker's test button. Record the resistance when the next LED lights permanently (this is the changeover resistance).

Example: The first green LED is illuminated 10^3 = 1 kilohm.
At 3 or 4 kilohms 10^4 LED is illuminated, the changeover point is 3 or 4 kilohms. 10^4 = 10 kilohms so between 3 or 4 kilohms and 30 or 40 kilohms will be the changeover points from 10^4 to 10^5. 

Please note that the checker has no internal parts to adjust, so verification of calibration 
can be achieved by using the above process. If verification cannot be achieved the unit 
should be returned to the supplier.