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TM9100 Service Manual Transmitter Fault Finding (50W/40W Radios) 249

Task 1 —

13.8V Power Supply

First check the power supply from the power connector.

1. Obtain a needle probe to use for measurements of the power supply

at the PA driver and PAs. If none is available, remove the

PAF TOP and

PAD TOP cans.

2. Set the DC power supply to 13.8V, with a current limit of 10A.

3. Program the radio with the highest

frequency in the radio’s frequency

band: Enter the CCTM command 101 x x 0, where x is the frequency

in hertz. The required values for the different frequency bands are

given in Table 11.2.

4. Enter the CCTM command 326 5 to set the radio to maximum

power.

5. Attempt to place the radio in transmit mode. Enter the CCTM

command 33.

6. If the radio enters the transmit mode, continue with Step 7. If instead

a C03 error is displayed in response to the command 33, go to Task 7

in “Transmitter RF Power” on page 262.

7. Measure the voltage at the point on L310 shown in Figure 11.2

(B1 band) or Figure 11.3 (H5, H7 bands). This is the supply at the

common drain of Q309 and Q310, and should be:

8. Also measure the voltage at the point on L306 shown in Figure 11.4

(B1 band) or Figure 11.5 (H5, H7 bands). This is the supply at the

drain of Q306, and should be:

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

10. If the power supply measured in Step 7 and Step 8 is not correct, go

to Task 2

. If it is, go to Task 3.

common drain of Q309 and Q310: more than 13V DC

drain of Q306: more than 13V DC

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