Voltages At Ic303 At Maximum Power (40 W) - Tait TM9100 Service Manual

Following the checks in
Task 22 —
Directional Coupler
circuitry as described in the remaining tasks of the section. In this task any
and Buffer
faults in the directional coupler or buffer amplifier will be located.
Amplifier
1.
2.
3.
4.
5.
6.
7.
8.
Table 12.7 Voltages at IC303 at maximum power (40 W)
Frequency band
B1
H5
H6
9.
10.
11.
12.
350 Transmitter Fault Finding (25W Radios)
Task 19
Cycle the power.
Enter the CCTM command 326 5 to set the transmitter to maximum
power.
Enter the CCTM command 33 to place the radio in transmit mode.
Measure the voltage at pin 9 of IC303 in the power-control circuit
(see Figure 12.9).
The above voltage should be as given in
Task 24. If it is not, go to
Check the voltage at pin 5 of IC303 (or use the
(see Figure 12.9). Note that the probe impedance might affect the
measurement.
Enter the CCTM command 32 to place the radio in receive mode.
The voltage measured in
If it is not, go to Step
Frequency (MHz)
136
155
174
400
435
470
450
490
530
Remove the
DIRC TOP
Check the components of the directional coupler (see
and go to Step 12.
Check R340 between pins 6 and 7 of IC303 in the buffer amplifier
(see Figure 12.13), and then go to
Repair any fault revealed by the above checks. Replace IC303 if none
of the other components is faulty (see
to Task 21, locate the fault and repair the
Table
Step 6.
Step 6 should be as given in
9. If it is, go to Step 11.
Voltage (V)
Pin 9
2.2 ± 0.5
2.3 ± 0.5
2.5 ± 0.5
3.4 ± 0.5
3.8 ± 0.5
4.0 ± 0.5
3.9 ± 0.5
4.2 ± 0.5
4.7 ± 0.5
can.
Step 12.
Figure
© Tait Electronics Limited August 2005
12.7. If it is, go to
test point)
FWD PWR
Table 12.7.
Pin 5 ( )
FWD PWR
1.9 ± 0.5
2.1 ± 0.5
2.3 ± 0.5
3.3 ± 0.5
3.7 ± 0.5
3.9 ± 0.5
3.8 ± 0.5
4.1 ± 0.5
4.6 ± 0.5
Figure 12.12)
12.9).
TM9100 Service Manual