Model N-10 Tester for Clamp-on DC Ammeters by Swain Meter

 
The Swain Meter 700 mA Tester N-10 drives 70 mA of direct current regulated to within ± 1 mA into a 10-turn loop which is 4 ½" in diameter. The leads are 3" long, so the 70 mA is also available.

The tester is intended to ensure the Swain Meter is functioning properly. The 70 mA current flows in the wire to the 10 turn loop from the red end towards the black end when the button is pushed, provided the LED appears bright.

To use, either the single turn or the 10-turn wire loop is placed in the aperture of the clip or clamp sensor, toward the center, or with a large clamp, along one side, away from the lips. When the wire is close to one side of a clamp, it is likely to read 1% or so higher than the 70 mA in the wire.

The "Zero" adjustment on the indicator may be set so that the meter reads zero before the 70 mA is turned on, but this is not necessary. We often read the meter with the 70 mA off, and then again with it on. The difference between the 2 meter readings should be 70 mA ± 2 mA for a single turn loop or 700 mA ± 10 mA for the 10 turn loop, when using a directly calibrated sensor. If not, check the calibration chart shipped with the sensor. Observe the polarity. It should agree with the calibrator.

If the LED is dim, or in any event after 4 hours of continuous use, or 4 months, whichever comes first, the two alkaline AA cells should be changed. The battery voltage must exceed 2.5 Volts when the LED is lit.