Check Forward And Reverse Powers - Tait TM9100 Service Manual

First check the forward and reverse powers for an indication of which part
Task 4 —
Check Forward and
of the circuitry is suspect.
Reverse Powers
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
TM9100 Service Manual
© Tait Electronics Limited August 2005
Enter the CCTM command 326 4 to set the transmitter power level
high.
Enter the CCTM command 33 to place the radio in transmit mode.
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
Confirm the above result by checking the level at the
point (see Figure 11.6) using an oscilloscope.
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
Confirm the above result by checking the level at the
point (see Figure 11.6) 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.
Enter the CCTM command 32 to place the radio in receive mode.
If the values obtained in Step 3
is no indication of a momentary high reverse power, go to
If one or both are incorrect, go to
Check the connection from the RF connector on the radio to the test
set.
If there is no fault, go to
repeat the above measurements.
If the reverse power is momentarily too high, the directional coupler,
PIN switch or LPF is suspect; go to
Transmitter Fault Finding (50W/40W Radios)
Table 11.3.
Table 11.3.
and Step 5 are both correct, and there
Step 9.
Step 11. If there is, rectify the fault and
Task 31. Otherwise go to
test
FWD PWR
test
REV PWR
Task 5.
Task 5.
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