TM8100/TM8200 Service Manual Transmitter Fault Finding (>25W) 323
© Tait Electronics Limited November 2007
Task 28 —
Output of Second
Stage of Exciter
If the output of the first stage of the exciter circuit is correct, check that of
the second stage at C3509 for the VHF/UHF bands or L307 for the K5
band:
1. With the radio still in transmit mode, measure the RF voltage after
C3509 for the VHF/UHF bands (see Figure 11.21) or L307 for the
K5 band (see Figure 11.22). (Use an RFP5401A RF probe or the
equivalent.) The required voltage should be as given in Table 11.8
(B1), Table 11.9 (G2), Table 11.10 (H5), Table 11.11 (H7), or
Table 11.12 (K5).
2. If the voltage is correct, go to Tas k 30
. If it is not, go to Step 3.
3. Enter the CCTM command 32 to place the radio in receive mode.
4. Check the components around Q3502 for the VHF/UHF bands
(see Figure 11.21) or Q303 for the K5 band (see Figure 11.22).
5. For the K5 band: Since the second stage of the exciter is also the final
stage, check the voltage across resistor R351:
Also check that the resistance of the resistor is 15Ω.
6. Repair any fault revealed by the above checks. Q3502 for the
VHF/UHF bands (see Figure 11.21) or Q303 for the K5 band (see
Figure 11.22) if none of the other components is faulty.
7. Confirm the removal of the fault and go to “Final Tasks” on
page 163. If the repair failed, replace the board and go to “Final
Tasks” on page 163.
Voltage across R351: 1.0V to 4.2V
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