326 Transmitter Fault Finding (50W/40W) TB7100 Service Manual
© Tait Electronics Limited October 2005
Task 27 —
Output of First
Stage of Exciter
If the synthesizer output is correct, check the output at C3505 of the first
stage of the exciter circuit.
1. If not already done, remove the
PAD TOP can.
2. Enter the CCTM command 326 x, where x defines the power level
selected in Task 26
.
3. Enter the CCTM command 101 x x 0, where x is the frequency
selected in Task 26
.
4. Enter the CCTM command 33 to place the radio in transmit mode.
5. Measure the RF voltage after C3505 (see Figure 14.21 and
Figure 14.22). (Use an RFP5401A RF probe or the equivalent.)
The required voltage should be as given in Table 14.8 (B1 band),
Table 14.9 (H5) or Table 14.10 (H7).
6. Enter the CCTM command 32 to place the radio in receive mode.
7. If the voltage measured above is correct, go to Task 29. If it is not, go
to Step 8.
8. Check the components around Q3501 (see Figure 14.21 and
Figure 14.22).
9. Repair any fault revealed by the above checks. Replace Q3501
(see Figure 14.21 and Figure 14.22) if none of the other
components is faulty.
10. 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.
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