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CHECK A3A2 2ND LO OUTPUTS
The two input signals to A3A2 are the 520 MHz signal coming from A5 and the 21.42 MHz
signal coming from A3A1. See Figure 7-1. Before performing the procedures in this section,
verify the 520 MHz signal in accordance with the Check A5 Synthesizer Outputs section and
verify the 21.42 MHz signal in accordance with the Check an A3A1 ALC Output section. In
addition, perform the RF OUT Level Correction Constants procedure (see the Adjustments and
Correction Constants chapter) to verify that the ALC circuit is working correctly.
The two output signals from A3A2 are the 2.08 GHz 2nd local oscillator signal going to the
A4A2 Receiver IF and the 2.05858 GHz signal going to the A3A3 source. Perform the following
procedures sequentially to verify these signals. If one of the signals is bad, replace A3A2.
In this procedure, the 2.05858 GHz signal level is controlled by the 4396B self-test functions.
For detailed information about the 4396B self-test functions, see the Service Key Menus.
1. Check the 2nd Local Oscillator Signal
The 2nd local oscillator signal is the 2.08 GHz CW signal a with signal level > +7 dBm (typical).
Perform the following steps to verify the frequency and level of the 2nd local oscillator signal:
a. Remove the \I" semi-rigid cable from A3A2J19 and remove the \D" cable from A3A1J3.
See Figure 7-22 for the locations of A3A2J19 and A3A1J3. Then connect the equipment as
shown in Figure 7-22.
Figure 7-22. 2nd LO OSC Test Setup
b. Initialize the spectrum analyzer. Then set the controls as follows:
Controls
Settings
Center Frequency
2.08 GHz
Span
1 MHz
Reference Level
20 dBm
c. On the spectrum analyzer, press 4PEAK SEARCH5 to move the marker to the peak of the 2nd
Local.
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Source Group Troubleshooting