Tait TB7100 Service Manual
Also see for TB7100: Installation guideInstallation and operation manualInstallation guideOperation manualFITTING INSTRUCTION
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TB7100 Service Manual Frequency Synthesizer Fault Finding 145© Tait Electronics Limited October 2005Task 1 —System Error A system error indicates a fault in the calibration of either the FCL or thefrequency synthesizer. To determine which is faulty, calibrate the VCXOand the transmit VCO as described below. (Always calibrate the former first,because the latter depends on the former.)1. Place the radio in CCTM.2. Enter the CCTM command 301 0 10 to calibrate the VCXO.The response will be one of the following three messages:■ “passed sanity check. Cal’d values put into effect”■ “failed sanity check. Cal’d values not in effect”■ “Cal failed: lock error”The first two messages will be preceded by four calibration values.3. In the case of the first message (passed), go to Step 4. In the case ofthe second and third messages (failed), the FCL is suspect; go to“Power Supply for FCL” on page 189.4. Enter the CCTM command 302 0 10 to calibrate the transmit VCO.The response will be one of the three messages listed in Step 2.The first two messages will be preceded by eight calibration values.Reset the radio and re-enter CCTM.5. If the calibration succeeded but the system error persists, replace themain-board assembly and go to “Final Tasks” on page 123. In thecase of the second message (failed sanity check), go to Step 6. In thecase of the third message (calibration failed), go to Step 8 (UHFradios) or “Power Supplies” on page 147 (VHF radios).6. Enter the CCTM command 205 to reset the calibration values to thedefault values. Then enter the CCTM command 302 0 10 again tocalibrate the transmit VCO.7. If the calibration succeeded, confirm the removal of the fault, and goto “Final Tasks” on page 123. If the calibration failed, go to Step 8(UHF radios) or “Power Supplies” on page 147 (VHF radios).8. Program the radio with the maximum frequency in the radio’sfrequency band: Enter the CCTM command 101 x x 0, where x is thefrequency in hertz.9. Enter the CCTM command 72 to determine the lock status in receivemode. Note the response.lock status=xyz (x=RF PLL; y=FCL; z=LO2) (0=not in lock; 1=in lock) |
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