Tait TB7100, Service Manual

Page: 208 / 370

210 Receiver Fault Finding TB7100 Service Manual
© Tait Electronics Limited October 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
FE TOP
can and, if not already done, the
IF TOP
can.
2. Check the soldering of all the components of the front-end tuning
circuitry from C400 to T401 (see
Figure 12.1 and Figure 12.3 ).
3. Check the IF-amplifier bias conditions as in Step 4 and Step 5 of
Task 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 31 to Task 33 of
“Transmitter Fault Finding (25 W)” on page 219 or “Transmitter
Fault Finding (50 W/40 W)” on page 273 .
7. Recalibrate the receiver using the calibration application.
8. Confirm the removal of the fault and go to “Final Tasks” on
page 123 . If the repair failed, replace the main-board assembly and go
to “Final Tasks” on page 123 .