Tait TP9100 - Page 162

162 Frequency Synthesizer Fault Finding TP9100 Service Manual
© Tait Electronics Limited May 2005
Task 2 —
Lock Status
A lock error indicates that the frequency synthesizer, FCL or second LO is
out of lock. To determine which is faulty, check the lock status as described
below.
1. If not already done, place the radio in CCTM.
2. Program the radio with the receive frequency of a channel that is
known 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 receive
mode. Note the response. The action required depends on the lock
status 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 power
supplies are functioning correctly; go to “Loop Filter” on page 176.
6. If the lock status is 010, the synthesizer and second LO are both out
of lock. First investigate the synthesizer, excluding the power supplies;
go to “Loop Filter” on page 176. If necessary, investigate the receiver
later.
7. If the lock status is 110, the second LO is out of lock. Investigate the
receiver; go to “Receiver Fault Finding” on page 251.
8. If the lock status is 111, this implies normal operation. But if the lock
error persists, replace the main board and go to “Final Tasks” on
page 134.
lock status=xyz (x=RF PLL; y=FCL; z=LO2) (0=not in lock; 1=in lock)