Tait TP9100 Service Manual

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162 Frequency Synthesizer Fault Finding TP9100 Service Manual© Tait Electronics Limited May 2005Task 2 óLock StatusA lock error indicates that the frequency synthesizer, FCL or second LO isout of lock. To determine which is faulty, check the lock status as describedbelow.1. If not already done, place the radio in CCTM.2. Program the radio with the receive frequency of a channel that isknown to be out of lock: Enter the CCTM command 101 x x 0,where x is the frequency in hertz.3. Enter the CCTM command 72 to determine the lock status in receivemode. Note the response. The action required depends on the lockstatus as described in the following steps.4. If the lock status is x0x, where x is 0 or 1, the FCL is suspect; go to“Power Supply for FCL” on page 205.5. If the lock status is 011, the synthesizer is suspect, although the powersupplies are functioning correctly; go to “Loop Filter” on page 176.6. If the lock status is 010, the synthesizer and second LO are both outof lock. First investigate the synthesizer, excluding the power supplies;go to “Loop Filter” on page 176. If necessary, investigate the receiverlater.7. If the lock status is 110, the second LO is out of lock. Investigate thereceiver; go to “Receiver Fault Finding” on page 251.8. If the lock status is 111, this implies normal operation. But if the lockerror persists, replace the main board and go to “Final Tasks” onpage 134.lock status=xyz (x=RF PLL; y=FCL; z=LO2) (0=not in lock; 1=in lock)