TB8100 Service Manual Power Amplifier Fault Finding 141
© Tait Electronics Limited September 2006
Power Foldback
The PA has detected a fault condition and has reduced its power output to
a minimal level to prevent damage. Check the other alarms to see what fault
condition or conditions have caused this.
Forward Power Low
The output power is below the configured threshold. Check that the alarm
threshold is not too high (Configure > Alarms > Thresholds). If the
threshold is above the recommended value given in Task 2
, decrease the
value and check whether the alarm is still present. If it is, go to Task 4
. If
it is not, go to “Visual Inspection” on page 144.
Reverse Power High
The reverse power output is above the configured threshold. Check that the
alarm threshold is not too low (Configure > Alarms > Thresholds). If the
threshold is below the recommended value given in Task 2
, increase the
value and check whether the alarm is still present. If it is not present, go to
“Visual Inspection” on page 144. If it is still present, proceed as follows:
■ check the load is not faulty
■ check the low pass filter (refer to “Low Pass Filter and Directional
Coupler Board” on page 165).
Calibration Invalid
Recalibrate the PA as described in the Calibration Kit documentation and
return to Task 1
.
Hardware Configuration Invalid
Select Monitor > Module Details > Power Amplifier and check that the
module details programmed into the PA are correct and match the actual
hardware configuration. If they are correct, it is possible there is a break in
the connectivity between boards. Go to “Visual Inspection” on page 144.
If they are not correct, reprogram the correct details into the PA using the
Calibration Kit (this requires a dongle) and then recalibrate the PA.
Driver Current High
Go to “6W Board” on page 155.
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