TM8100/TM8200 Service Manual Transmitter Fault Finding (40W/50W) 309
© Tait Electronics Limited June 2006
Task 29 —
Output of Third
Stage of Exciter
If the output of the second stage of the exciter circuit is correct, check that
of the third and final stage at C307.
1. With the radio still in transmit mode, measure the RF voltage after
C307 (see Figure 11.17). (Use an RFP5401A RF probe or the
equivalent.) The required voltage should be as given in Table 11.8
(B1), Table 11.9 (H5) or Table 11.10 (H7).
2. If the voltage is correct, go to Tas k 3 0
. If it is not, go toStep 3.
3. With the radio still in transmit mode, measure the RF voltage at the
junction of R3525 and C3512 (see Figure 11.17). The voltage
should be:
4. Enter the CCTM command 32 to place the radio in receive mode.
5. If the voltage measured in Step 3 is correct, go to Step 7. If it is not,
go to Step 6.
6. Check the components around Q3504 (see Figure 11.17). Repair
any fault. Replace Q3504 if none of the other components is faulty.
Conclude with Step 8.
7. Check the components around Q3505 (see Figure 11.17). Repair
any fault. Replace Q3505 if none of the other components is faulty.
8. Confirm the removal of the fault and go to “Final Tasks” on
page 157. If the repair failed, replace the board and go to “Final
Tasks” on page 157.
junction of R3525 and C3512: 1.3 ± 0.2V (VHF)
1.8 ± 0.2V (UHF)
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