Second If And Repair Of Matching Circuitry - Tait TM9100 Service Manual

If the TCXO is not faulty, check the second IF and, if necessary, repair the
Task 18 —
Second IF and
matching circuitry.
Repair of Matching
Circuitry
1.
2.
3.
4.
5.
6.
7.
8.
TM9100 Service Manual
© Tait Electronics Limited August 2005
Input a large unmodulated RF input signal exceeding –90dBm at the
RF connector.
Use a needle probe to measure the frequency of the signal at the
test point — access is through the hole in the
(see Figure 10.1). The frequency is the second IF and should be:
frequency at QN test point: 64.000kHz
If the second IF is correct, go to
Recalibrate the TCXO.
Check if the distortion fault has been removed. If it has, go to
Tasks" on page 147. If it has not, go to
Remove the can.
IF TOP
Check the components between T401 and IC400 — these form the
matching circuitry for the crystal filters XF400 and XF401
(see Figure 10.1).
Repair any fault, confirm the removal of the fault, and go to
Tasks" on page 147. If the repair failed or no fault could be found,
replace the main-board assembly and go to
page 147.
can
IF TOP
Step 6. If it is not, go to
Step 6.
"Final Tasks" on
Receiver Fault Finding
QN
Step 4.
"Final
"Final
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