150 Keysight CXG, EXG, and MXG X-Series Signal Generators Service Guide
Troubleshooting
Amplitude Modulation Issues (Option UNT)
Amplitude Modulation Issues (Option UNT)
Depending on the instrument model number a problem with amplitude
modulation could be caused by different assemblies due to the different
hardware configurations. Refer to the section below for the model number
being serviced for information on isolating the cause of the problem.
N5166B, N5171B, N5172B, N5181B, N5182B
For these instruments the amplitude modulation generator and modulators are
all contained on the A3 RF assembly, so any AM failures that are due to a
hardware failure will require the replacement of the A3 RF assembly. However,
it is possible that an amplitude modulation failure could be caused by invalid
calibration array data. So before replacing the A3 RF assembly for an
amplitude modulation failure run the following adjustment:
AM Calibration
If the failure persists after the adjustment replace the A3 RF assembly.
N5173B, N5183B
For these instruments the amplitude modulation generator is located on the A3
RF assembly while there are two different modulators used, one on the A3 RF
assembly and one on the A7 Micro-Deck assembly. See Table 6-9 for
information as to which one is used for what frequency range.
9 kHz to <3.2 GHz
Since both the amplitude modulation generator and modulators used for
amplitude modulation in this frequency range are contained on the A3 RF
assembly, any amplitude modulation failures that are due to a hardware failure
will require the replacement of the A3 RF assembly. However, it is possible that
an amplitude modulation failure could be caused by invalid calibration array
data. So before replacing the A3 RF assembly for an amplitude modulation
failure run the following adjustment:
The instrument can use either an internal or an external amplitude
modulation generator to drive the amplitude modulator. This
troubleshooting procedure deals only with the internal generator. If there
is a problem only when using a valid external source, replace the A3 RF
assembly.
Table 6-9 Amplitude Modulation Control versus Frequency
Frequency Range AM Generator Amplitude Modulator
9 kHz to < 3.2 GHz A3 RF Assembly A3 RF Assembly
3.2 GHz to Max Frequency A3 RF Assembly A7A3 Mod-Filter Assembly
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