E8257D/67D, E8663D PSG Signal Generators Service Guide
Troubleshooting
Troubleshooting Unlevels
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• Set the amplitude to –15 dBm. The voltage on the center pin should decrease a few mVdc.
• If the voltages are good, replace the A30 Modulation Filter.
• If the voltages are bad, go to step 7.
b. If Option 540, measure the signal going into J3 and out of J2 on the A27 40 GHz Doubler. If the loss is greater
than 2.5 dBm, replace the A27 40 GHz Doubler.
c. If Option 550 or 567, measure the signal going into J3 and out of J2 on the A27 40 GHz Doubler. If the loss is
greater than 2.5 dBm, replace the A36 Quadraplier.
d. If Option 532 or 544, measure the signal going into J1 and out of J2 on the A37 Upconverter. The loss should
be less than 5 dBm. If the loss is 5 dBm or greater, replace the A37 Upconverter.
9. Unleveled only between 20 GHz and 40 GHz or 44 GHz. If the unleveled condition occurs between 20 GHz and
40 GHz, the problem is either with the A27 40 GHz Doubler or the A25 Highband Coupler/Detector.
a. Checking the A25 Highband Coupler/Detector:
• Using a spectrum analyzer, check at the RF output signal level to the level shown in the Maximum Leveled
Power table. The RF output level must be greater than the maximum specified power level.
• If the maximum power level is not greater than the maximum power level specified, troubleshoot the RF
path starting with the signals out of the A30 Modulation Filter to the A27 40 GHz Doubler.
— If Option 550 or 567, replace the A36 Quadraplier.
— If Option 532 or 544, replace the A37 Upconverter.
• If the signal is greater than the maximum specified power level, replace the A25 Highband
Coupler/Detector.
10. Unleveled from >3.2 GHz to the maximum frequency.
Option 540 – Using the RF path block diagram, check the output levels of the A29 20 GHz Doubler, the
A30 Modulation Filter, and the A27 40 GHz Doubler.
Options 550 and 567 – Using the RF path block diagram, check the output levels of the A29 20 GHz Doubler, the
A30 Modulation Filter, and the A36 Quadraplier.
Option 532 and 544 – Using the RF path block diagram, check the output levels of the A35 20 GHz IQ Modulator,
the A27 40 GHz Doubler, and the A37 Upconverter.
11. Unleveled at all frequencies.
If the signal generator is unleveled at all frequencies, the problem is most likely the A10 ALC.
a. Checking the A10 ALC:
• Run a complete self–test and troubleshoot the reported failure.
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