TM8100/TM8200 Service Manual
Transmitter Fault Finding (40W/50W)
271
© Tait Electronics Limited
June 2006
Task 4 —
Check Forward and
Reverse Powers
First check the forward and reverse powers for an indication of which part
of the circuitry is suspect.
1.
Enter the CCTM command
326 4
to set the transmitter power level
high.
2.
Enter the CCTM command
33
to place the radio in transmit mode.
3.
Enter the CCTM command
318
to check the forward power.
The value returned is the voltage in millivolts corresponding to the
power level, and should be as shown in
4.
Confirm the above result by checking the level at the
FWD
PWR
test
point
(see
) using an oscilloscope.
5.
Enter the CCTM command
319
to check the reverse power.
The value returned is the voltage in millivolts corresponding to the
power level, and should be as shown in
6.
Confirm the above result by checking the level at the
REV
PWR
test
point
(see
) using an oscilloscope.
If the oscilloscope momentarily indicates a very high reverse power,
then the most likely scenario is that the antenna VSWR threshold has
been exceeded and the PA has shut down to very low power.
7.
Enter the CCTM command
32
to place the radio in receive mode.
8.
If the values obtained in
are both correct, and there
is no indication of a momentary high reverse power, go to
If one or both are incorrect, go to
.
9.
Check the connection from the RF connector on the radio to the test
set.
10.
. If there is, rectify the fault and
repeat the above measurements.
11.
If the reverse power is momentarily too high, the directional coupler,
PIN switch or LPF is suspect; go to
. Otherwise go to
.
Summary of Contents for TM8235
Page 1: ...TM8100 mobiles TM8200 mobiles Service Manual MMA 00005 04 Issue 4 June 2006...
Page 10: ...10 TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 62: ...62 Description TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 148: ...148 Disassembly and Reassembly TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 162: ...162 Servicing Procedures TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 178: ...178 Interface Fault Finding TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 258: ...258 Receiver Fault Finding TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
Page 446: ...446 Spare Parts TM8100 TM8200 Service Manual Tait Electronics Limited June 2006...
