Installation guide

Troubleshooting
Troubleshooting Assembly Level Problems
1-37
404 Marble Test
• Measure the Q signal from the A10 I/Q Multiplexer.
a. Disconnect the cable from J3 of the A19 Daughterboard and connect it to a DVM.
b. Set the CW frequency to 2 GHz.
c. Turn on the I/Q modulation and adjust the Q offset.
d. Press the following keys:
—
I/Q hardkey / I/Q On / I/Q Adjustments / I/Q Adjustments On / Q Offset
e. Rotate the RPG and observe the DVM. The voltage should vary from approximately +0.25 Vdc for an
offset of 50% to approximately -0.25 Vdc for an offset of -50%.
— If the signal is bad, check it at J10 of the A10 I/Q Multiplexer.
— If the signal is bad at J10, refer to A10 I/Q Multiplexer troubleshooting.
— If the signal is good at J10, change the cable.
• Measure the I signal from the A10 I/Q Multiplexer.
a. Disconnect the cable from J2 of the A19 Daughterboard and connect it to a DVM.
b. Set the CW frequency to 2 GHz.
c. Turn on the I/Q modulation and adjust the I offset.
d. Press the following keys:
—
I/Q hardkey / I/Q On / I/Q Adjustments / I/Q Adjustments On / I Offset
e. Rotate the RPG and observe the DVM. The voltage should vary from approximately +0.25 Vdc for an
offset of 50% to approximately -0.25 Vdc for an offset of -50%.
— If the signal is bad, check it at J9 of the A10 I/Q Multiplexer.
— If the signal is bad at J9, refer to A10 I/Q Multiplexer troubleshooting.
— If the signal is good at J9, change the cable.
• If the I and Q signals are good, replace the A13 Output.
(Refer to “A13 Output” on page 2-32.)
405 Gain Adjustment Test
• Replace the A13 Output.
406 Prelevel Bypass Test
• Replace the A13 Output.
407 Switched filters Test
• Replace the A13 Output.
408 ALC Reference Test
• Replace the A13 Output.