ETS-Lindgren HI-2790B Calibration Comparison System - Manual (Page 23)

www.ets-lindgren.com Operation 23
Calibration Comparison
4.5.1 With the Power/Control Module RF POWER set to OFF, check
that the instrument being checked is properly zeroed. Turn the
RF Power switch on and check that the indicated RF POWER is
1.0 mW/cm 2 as established in step 4.1.9 on page 19. Rotate the
probe slowly through one full revolution (360 degrees) and record
the maximum and minimum readings.
4.5.2 Add the MAX reading to the MIN reading and divide the sum by
two. The result is the MEAN value.
4.5.3 Subtract the MIN reading from the MAX reading, divide the result
by the MEAN reading from the previous step, and then multiply
this result by 100. This is the TOTAL ELLIPTICITY in percent. The
maximum allowable ellipticity should be obtained from the
manufacturer specifications. Enter these values into the
Calibration Comparison Log.
Example: The test indicates a MAX value of 1.023 and a MIN value
of 0.985.
 Add 1.023 and 0.985. This equals 2.008.
 Divide 2.008 by 2. This gives a MEAN value of 1.004.
 Subtract the MIN value (0.985) from the MAX value (1.023).
This gives a value of 0.038.
Divide 0.038 by the MEAN value (1.004), and then multiply the
result by 100. This gives a TOTAL ELLIPTICITY of 3.78%.