| Troubleshooting the Test Set |
| Theory of Operation |
| • If the test set is equipped with Option 001 (multiple test set capability), |
| its begin state is inactive. That is, rather than using the test set’s internal |
| IF, a switch is set in the test set to accept an IF from another test set. |
The LO Signal Control | The LO, generated by A14 VTO/driver, is phase locked to the source so the |
| desired VTO harmonic is 20 MHz greater than the source frequency. |
| The |
| • Portions of the test set, such as the VTO |
| VTO/driver (A14), and the a1 sampler assembly (A10), and |
| • The HP 8510C Network Analyzer |
| The VTO |
| VTO to the correct LO frequency. |
| The VTO also has an output LENDRA (Low END of RAnge) which is |
| routed via the test set interconnect cable, to the HP 85102. |
| The LENDRA provides an indication to the network analyzer about whether |
| or not the VTO is operating within its normal frequency range. |
| If the VTO exceeds its normal frequency range, the network analyzer |
| displays the running error message VTO OVER RANGE. |
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CAUTION | Electrostatic Discharge Sensitive (ESD) Assemblies |
| Assemblies you might handle in these troubleshooting procedures are |
| extremely sensitive to damage from static electricity. They may or may not |
| continue to function if they are subjected to electrostatic discharge. Their |
| reliability, however, will be impaired. |
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