Tait TP9100 - Page 260

260 Receiver Fault Finding TP9100 Service Manual
© Tait Electronics Limited May 2005
Task 9 —
Slightly Low
Sensitivity
Following the initial investigation in Task 7, check the circuitry as follows
when the sensitivity loss is slight.
1. Remove the
RX FE TOP can and, if not already done, the IF IQ BOT can.
2. Check the soldering of all the components of the front-end tuning
circuitry from C400 to T401 (see Figure 11.3 and Figure 11.4).
3. Check the IF-amplifier bias conditions as in Step 4 and Step 5 of
Ta sk 5
.
4. Check the LNA bias conditions as in Step 4 and Step 5 of Task 8
.
5. If the checks of Step 2 to Step 4 reveal no fault, go to Step 6.
If there is a fault, repair it and go to Step 7.
6. Check the PIN switch and LPF as in Task 21
to Task 2 3 of
“Transmitter Fault Finding”.
7. Recalibrate the receiver using the calibration application.
8. Confirm the removal of the fault and go to “Final Tasks” on
page 134. If the repair failed, replace the main board and go to “Final
Tasks” on page 134.