You don't give us much to work with. Try changing the inputt attenuator setting with the calibrator signal connected. Default is 10 dB. Step through the entire range, from 0 to 70 dB and see if the signal level changes. Do this while the scale is 10dB/div. To set the attenuator to 0dB, you will have to enter "0" via the number pad.
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Vladan
