Agilent Technologies Agilent 4396B, Service Manual

Page: 147 / 324

CHECK AN A3A1 ALC OUTPUT
The input signal to the A3A1 ALC is the 40 MHz reference signal coming from A5 (see
Figure 7-1). Before performing the procedures in this section, verify the CAL OUT signal in
accordance with the Check A5 Synthesizer Outputs section. This ensures that the 40 MHz
reference signal is good. In addition, perform the RF OUT Level Correction Constants (see
the A djustments and Correction Constants chapter) to verify that the ALC circuit is working
correctly .
The three output signals from A3A1 are the 21.42 MHz signal with the level controlled by the
automatic leveling control (ALC) circuit, the 8 MHz reference signal, and the 40 kHz reference
signal.
P erform the following procedures sequentially to verify the 21.42 MHz signal. If the signal is
bad, replace A3A1.
In this procedure , only the 21.42 MHz signal is veried. This is because the 8 MHz and 40
kHz reference signals are veried by running internal test 11 in the Start Here . The 21.42
MHz signal is observed using test equipment and its level is controlled by the 4396B self-test
functions . F or detailed information about the 4396B self-test functions , see the Service K ey
Menus.
1. Check the 21.42 MHz Signal
P erform the following steps to verify the 21.42 MHz signal:
a. Remove the \D" cable from A3A2J22. See Figure 7-20 for the location of A3A2J22. Then
connect the equipment to the \D" cable as shown in Figure 7-20 .
Figure 7-20. ALC Outputs T est Setup
b.
Press 4 Meas 5 ,
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
ANALYZER TYPE ,
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
NETWORK ANALYZER , 4 Preset 5 to initialize the 4396B .
c. Initialize the spectrum analyzer . Then set the controls as follows:
Controls Settings
Center Frequency 21.42 MHz
Source Group T roubleshooting 7-23