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310 Transmitter Fault Finding (40W/50W) TM8100/TM8200 Service Manual

Task 3 0 —

Output of PA Driver

If the exciter output is correct, check the output of the PA driver at the

drain of Q306. If necessary, also check the signal at the gates of the PAs

Q309 and Q310. This is the last point in the initial RF signal path.

1. With the radio still in transmit mode, measure the RF voltage at the

drain of Q306 (B1) or after C317 and C389 (other bands). See

Figure 11.17 and 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. Enter the CCTM command 32 to place the radio in receive mode.

3. If the voltage measured above is correct, go to Step 7. If it is not, go

to Step 4.

4. Check the components between C307 and Q306

(see Figure 11.17).

5. If the above checks reveal a fault, go to Step 6. If they do not, go to

Tas k 12

in “Biasing of PA Driver and PAs” on page 280.

6. Repair the fault. 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.

7. If not already done, remove the

PAF TOP can.

8. Enter the CCTM command 326 5 to set the power level to the

maximum, and then the command 33 to place the radio in transmit

mode.

9. Measure the RF voltage at the gates of the PAs Q309 and Q310

(see Figure 11.18 and Figure 11.19).

10. Enter the CCTM command 32 to place the radio in receive mode.

11. If an RF voltage is present, there is no fault in the initial RF signal

path; go to Task 31

. If there is no RF voltage, go to Step 12.

12. Check the components of the interstage matching circuitry between

the PA driver Q306 and the gates of the PAs Q309 and Q310

(see Figure 11.18 and Figure 11.19).

13. If a fault is found, repair it, confirm the removal of the fault, and go

to “Final Tasks” on page 157. If the repair failed or the fault could

not be found, replace the board and go to “Final Tasks” on page 157.

Tait TM8110 Service Manual

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