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Trouble Shooting Guide, Advanced
Fig. 10.5
If the up- and down-ramping looks like the pictures above, the fault almost always is due to
distortion caused by the power amplifier.
Replace N401 and do a new radio calibration.
The few times the fault are not due to N401 is it usually N560/N570 or C404, parts of the
exponential amplifier, that is faulty.
If the up- and down ramping does not look like the pictures, the fault can be due to the
exponential amplifier, the low pass filter or the offset voltage.
All three of the parts are functions in N450.
If the offset voltage is too low, the fault probably is due to N450.
If the offset voltage is too high, the fault probably is due to C411 or N411.
When C411 is faulty, it can be difficult to calibrate the lowest power levels.
If the up- and down-ramping is steeper and/or there is a large curve in the middle of the
ramping, is it the low pass filter or the exponential amplifier that is faulty.
The fault is due to C403, C404 or N450.
If the up- and down ramping is considerably shorter then in the pictures, the fault is due to either
C401 or N450.
When C401 is faulty, it can be difficult to calibrate the lowest power levels.
4/00021-3/FEA 209 544/18 B
47(121)
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