234 Transmitter Fault Finding TP9100 Service Manual
© Tait Electronics Limited May 2005
Task 11 —
Shaper and
Level Shifter
If the voltage measured in Task 10 is correct but not the current, either the
PA or the shaper and level shifter for the PA is suspect.
Important Ensure that the current limit on the DC supply is 2A. And,
when entering the CCTM command 331 x, do not specify
a value x higher than that recorded in Task 9. Failure to do
so might result in the destruction of the PAs.
1. Enter the CCTM command 33 to place the radio in transmit mode.
2. Enter the CCTM command 331 x (where x was recorded in Task 9).
3. Check that the voltage at the gate of Q106 (see Figure 10.8) is:
4. Enter the CCTM command 32 to place the radio in receive mode.
5. If the voltage measured above is correct, Q106 is faulty; replace the
main board and go to “Final Tasks” on page 134. If it is not correct,
go to Step 6.
6. Check the circuitry between pin 14 of IC101 (see Figure 10.7) and
the gate of Q106 (see Figure 10.8). If a fault is found, repair it,
confirm the removal of the fault, and go to “Final Tasks” on
page 134. If the repair failed or Q106 itself is faulty, replace the main
board and go to “Final Tasks” on page 134.
gate of Q106: 2 to 5V
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