Installation guide

Troubleshooting
Troubleshooting Unlevels and the RF Path
1-77
Unleveled or Low Power for Frequencies ≥ 250 MHz and ≤ 4 GHz
NOTE Before proceeding to troubleshoot with this section, run a full self-test and correct any reported
failures and unlock problems. (Refer to “Self-Test Failures and Related Troubleshooting” on
page 1-19 and “Troubleshooting Unlocks” on page 1-68.)
1. Set the signal generator to the unleveled frequency.
2. With the signal generator powered on, carefully remove the A13 Output.
3. Use a semi-rigid cable extender and connect a spectrum analyzer to the A16 Frac-N (Option UNJ or
Option 506) or A17 Synthesizer (Option 501, 502, 503, 504) RF output at J4 of the A13 Output.
The signal at J4 should be the same frequency that the signal generator is set to and the amplitude
at J4 should be ≥ 0 dBm.
• If the J4 signal is good, replace the A13 Output.
• If the J4 signal is bad and the instrument is an:
— Option 501, 502, 503, 504, change the A17 Synthesizer (Option 501, 502, 503, 504)
— Option UNJ, check the signal leaving the YIG Oscillator.
The YIG frequency will be higher that the front panel frequency. It is divided down with the divisor
being dependent on the front panel frequency.
— If the signal is good, change the A16 Frac-N (Option UNJ or Option 506).
— If the signal is bad out of the YIG, change the A21 YTO Driver (Option UNJ or Option 506)
— Option 506, check the signal at the input of the A22 Coupler (Option 506).
— If the signal is good, replace the A22 Coupler (Option 506).
— If the signal is bad, check the signal leaving the YIG Oscillator.
The YIG frequency will be higher than the front panel frequency. It is divided down with the
divisor being dependent on the front panel frequency.
— If the signal is good, replace the semi-rigid cable (W54) between the YIG Oscillator and the
input of the A22 Coupler (Option 506).
(Refer to “Option 506 - Semi-Rigid Cables includes the A21 YTO Driver (Option UNJ or
Option 506) and the AT1 High-Power Mechanical Attenuator (Option UNB) with an A29 DC
Blocking Capacitor (Option 506)” on page 3-65.)
— If the signal is bad, change the A21 YTO Driver (Option UNJ or Option 506).