Agilent Technologies HP 8719D Service Manual page 242

5. Check all RF cabling and connections.
If any of the cables or connectors are bad, have them repaired or replaced.
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If the cables and connectors are good, replace the A55 YIG 1. If mid band
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problems still persist, then replace the A58 M/A/D/S.
High Band Problems: (HP 8722D Only)
BAND
tuning the instrument from about 19.5 to 24 GHz). Loss of lock in high band
only may likely be due to a bad cable or connection.
2. Referring to the overall block diagram, the following components may be at
fault:
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3. Since the analyzer phase locked in low and/or mid band, all of the phase lock
circuitry is working, so look for low power as a cause of phase lock errors,
4. Check power at the output of Sl.
If the power is less than +5 dBm, check the insertion loss of Sl and the
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associated cabling.
If the power out of Sl is greater than + 5 dBm, the problem is probably
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above 24 GHz. Proceed with the next steps.
5. Check all RF cabling and connections.
If any of the cables or connectors are bad, have them repaired or replaced.
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If the cables and connectors are good, replace the A54 YIG 2. If high band
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problems still persist, then replace the A58 M/A/D/S.