HP 8924E, Сборка

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Chapter 14, Diagnostics Descriptions
Description of RF Diagnostics (RFDIAGS3)
N:\mkt\MANUALS\HP8924C\ALR\diagnos.fb
Step Attenuator See Path 1, Node 2 in figure 70 on page 590 . The
step attenuator is checked by switching-in one
pad at a time. The limits are set in terms of the no
signal (RF Detector (Low Power), No Signal)
reading obtained in the test and the difference
between the readings obtained in the previous RF
Detector (Low Power) Signal Present and No
Signal tests.
DVM:RF_PK_DET_LOW
Antenna Input
Detector See Path 3, Node 4 in figure 71 on page 591 . The
antenna input detector cannot read the internal
signal level in the Input module. It is read anyway
to be sure it is zero. If the test fails it could be
because there is a signal being applied to the
front-panel ANT IN connector.
DVM:ANTENNA_DET
Filter Output
Detector, No
Signal See Path 3, Node 5 in figure 71 on page 591 . All
the switches that connect the signal to the
Receiver’s output EXCEPT the antenna switch
are set. Thus, there is NO signal yet on the filter
output detector. The detector should read zero.
DVM:FILTER_OUT_DET
Filter Output
Detector, Signal
Present See Path 4, Node 5 in figure 71 on page 591 . The
filters are checked by setting the RF Analyzer and
RF source to the same frequencies (1, 100,300,
600, 800, 1000 MHz). The frequencies are
selected so each filter is checked. Setting the ana-
lyzer frequency’s sets the right filter.
DVM:FILTER_OUT_DET
Output Filter
Rejection See Path 4, Node 5 in figure 71 on page 591 .
Each filter is checked to see that it rejects signals
outside of its passband. The filter is selected
using the analyzer’s frequency command.
DVM:FILTER_OUT_DET
Output Vari-
able Attenuator See Path 4, Node 5 in figure 71 on page 591 .The
variable attenuator is checked by programming
the DAC to full scale and reading the voltage on
the output detector. Then the DAC is pro-
grammed to values which turn on the 5 most sig-
nificant bits, 1 bit at a time, starting with the
MSB. In each case the output detector is mea-
sured and checked to see if the voltage is less than
the previous reading (last).
DVM:FILTER_OUT_DET
Table 126 A5 Input Tests (Continued)
Measurement Explanation and Suggestions Measurement Point