OM POWER OM2501A - Troubleshooting

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7.11 Troubleshooting
The OM2501A (OM3501A) 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 25). 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. (M-
TUNE)
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 +20 mA
• Press PTT without driving If screen current is
higher than +5mA then plate voltage is
missing. Check plate fuse (page 32).