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7.6. Troubleshooting
The power amplifier contains several protection circuits, which constantly monitor operation
of the Amplifier. When the firmware defined parameters exceed defined operating levels, a WARNING
appears in the LAST EVENTS window of the PA front panel. If some parameters exceed a defined critical
level, a FAULT is activated and the PA will automatically switch to STBY mode. The LAST EVENTS window
will then display the fault information.
All of these events are written to the FAULT and WARNING memories. The Last event is visible after the
LAST EVENTS button is pressed including information about possible causes.
There are several warning or fault messages that may appear on the display:
Warning / Fault
Action
Description
Power Out is too high
Reduce input power
Output power exceeds maximum level, reduce the input
power.
Refl. power too high
Check your antenna
Reduce output power
Reflected power exceeds maximum allowed level. Check if
proper antenna is connected. In the case of higher SWR
reduce the input power and thus the output and reflected
power will be lower.
SWR is too high
Check your antenna
Check antenna switch
Antenna SWR is too high (SWR 3 for WARNING and SWR 5
for FAULT). Check if proper antenna is connected. Check
antenna switch configuration. If you want to use an antenna
with higher SWR, this SWR protection can be switched off
(page 22). But reflected power will stay checked
(max.350W).
Power In is too high
Reduce input power
Check amplifier tuning
PA input is too high - decrease it!
If maximum output power is not achievable, check plate
voltage and PA tuning.
Low output power
(tune)
Tune mistake.
Retune your amplifier
The PA has lower gain and may not be properly tuned.
Check the plate voltage and Screen current. If they are ok,
manually adjust for optimal tuning of the PA
Plate current too high
Reduce input power
Check amplifier tuning
Check EBS setting
Plate current too high. Check the following:
•
Too high input power – reduce it
•
Improper tuning of the PA – bad antenna
impedance matching. Tune the PA properly.
•
Improper BIAS setting. Check EBS1 and EBS2.
Grid current is high
Reduce input power
Check amplifier tuning
Grid current too high is due to overdriving the PA. Reduce
the input power. If maximum output power is no reachable
due to high plate current, check the PA tuning.
Screen current error
Reduce input power
Check amplifier tuning
Check plate voltage fuse
High screen current is usually due to the following reasons:
•
Overdriving the PA – reduce the input power
•
Improper PA tuning. At maximum output power
the screen current must be inside the range of 0
mA to
+30 mA
•
Plate voltage is missing. Press PTT without driving.
If screen current is higher than +20mA, check plate
voltage fuse (page 26).
