Installation guide

Troubleshooting
Troubleshooting Unlevels and the RF Path
1-76
Troubleshooting the RF Path
Depending on the frequency range that an unlevel is occurring, refer to one of the following:
• Unleveled or Low Power for Frequencies ≥ 250 kHz and < 250 MHz on page 1-76
• Unleveled or Low Power for Frequencies ≥ 250 MHz and ≤ 4 GHz on page 1-77
• Unleveled or Low Power for Frequencies > 4 GHz and ≤ 6 GHz (Option 506 Only) on page 1-78
Unleveled or Low Power for Frequencies ≥ 250 kHz and < 250 MHz
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 frequency where the signal generator is unleveled.
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 and
measure the power level.
The amplitude of the signal at J4 should be ≥ 5 dBm and the RF frequency at J4 is determined by the
following equation:
J4 Frequency = 1 GHz - Front Panel RF Frequency
• 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, replace the A17 Synthesizer (Option 501, 502, 503, 504)
— Option UNJ or Option 506, check the signal leaving
the YIG oscillator.
The YIG frequency is determined by the equation:
YIG Frequency = (1 GHz - Front Panel RF Frequency) * 8
— If the signal is good out of the YIG, replace the A16 Frac-N (Option UNJ or Option 506).
— If the signal is bad out of the YIG, replace 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 is determined by the equation:
YIG Frequency = (1 GHz - Front Panel RF Frequency) * 8
— If the signal is good, replace the semi-rigid cable (W54) between the YIG Oscillator and the
input of the A22 Coupler (Option 506)
— If the signal is bad, replace the A21 YTO Driver (Option UNJ or Option 506).