Chapter 8 413
IF Section
Troubleshooting Using the TAM
3. Set the other spectrum analyzer controls as follows:
Span .......................................................................... 5MHz
Reference level ...................................................... −20dBm
Center frequency ................................................. 10.7MHz
4. On the HP 8560E/EC, set the cal oscillator to 10.7 MHz by selecting
Fixed Tuned to 10.7 MHz.
5. A −25 dBm signal from A5J5 should be displayed. If the signal is
missing, disconnect W52 (coax 9) from A5J4. This is the cal oscillator
signal input from the cal oscillator on the A4 assembly.
6. Connect the end of cable W52 to the input of the second spectrum
analyzer. The signal coming from cable W52 should be −35 dBm at
10.7 MHz. If the cal oscillator signal from cable W52 is correct, the
A5 IF assembly is probably at fault.
Troubleshooting the Cal Oscillator with the TAM
1. Enter the TAM Cal Osc Troubleshooting Mode.
2. On the spectrum analyzer, disconnect cable W52 (coax 9) from A5J4
and connect this end of cable W52 to the input of a second spectrum
analyzer.
3. Set the controls of the second spectrum analyzer connected to cable
W52 to the following:
Span ...........................................................................5MHz
Reference level ...................................................... −30dBm
Center frequency .................................................. 10.7MHz
4. Select each of the fixed-tuned frequencies. Verify at each frequency
that the signal amplitude measures −35 dBm. If the frequency is
incorrect, do the following:
a. Verify that the reference divider output (A4U811 pin 9) is 100
kHz. If it is not, verify that the 10 MHz reference is present at
A4U811 pin 1.
b. Verify that the frequency found on the output of the divider
(A4U808 pin 15) matches the output of the reference divider.
Matching frequencies indicate the oscillator loop is locked. If the
loop is not locked, troubleshoot the divider, oscillator, or phase
detector.
c. Verify that the frequency found at the divider input (A4U808 pin
3) matches the CW frequency chosen in step a. Matching
frequencies indicate a properly working oscillator. If the
frequency is different, troubleshoot the divider.
d. Repeat step c for all the CW frequencies provided by the test.
5. Select each of the sweep widths (these sweeps are centered about
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