Tait TP9100, Service Manual, Page: 221 / 326

TP9100 Service Manual
Transmitter Fault Finding 221
© Tait Electronics Limited May 2005
Task 1 —
7.5V Power Supply
First check the 7.5V power supply.
1. Remove
PA BOT
can,
PA LPF BOT
can, and
TX CONTROL BOT
can, and carry
out a thorough visual inspection
2. Obtain a needle probe to use for measurements of the power supply
at the PA driver and PAs.
3. Set the DC power supply to 7.5 V, with a current limit of 3A.
4. 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 10.2 on page 218 .
5. Enter the CCTM command
326 4
to set the radio to high power.
Note
Using the CCTM command
326 5
will set the radio to maximum
power and the driver stage will be under current limiting.
6. Attempt to place the radio in transmit mode. Enter the CCTM
command
33 .
7. If the radio enters the transmit mode, continue with Step 8 . If instead
a C03 error is displayed in response to the command 33 , go to Task 5
on page 227 .
8. Measure the voltage at the point on L115 shown in Figure 10.2 .
This is the supply at the drain of Q106 , and should be:
9. Also measure the voltage at the point on L111 shown in
Figure 10.2 . This is the supply at the drain of Q103 , and should be:
10. Enter the CCTM command 32 to place the radio in receive mode.
11. If the power supply measured in Step 8 and Step 9 is correct, go to
Task 2 . If it is not, go to “Power Supply Fault Finding” on page 149 .
drain of Q106: approximately 7.0V DC
drain of Q103: approximately 7.0V DC