Nautel NV7.5, Operation And Maintenance Manual

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NV10/NV7.5 Operations and Maintenance Manual Operating the transmitter
Issue 3.4 2016-08-03 Page 2-75
IPA bias balance
IPA Bias Balance
(see Figure 2.49 on page 2-76 ) allows for optimal balancing of RF power
module outputs to minimize reject load power. An
IPA Balancing Recommended Alarm
will be
generated when balancing is suggested. This may occur after an RF power module has been
replaced or repaired. While RF is enabled (on) and the transmitter is operating at the desired
power level in the desired preset, press the
Start
button to initiate the process. When the
process has been completed, the
Save
and
Cancel
buttons will activate to either save the result
to the active preset or abort the function without affecting the previous balance. Note that the
user may press
Stop
while a balancing is in process but still save or cancel the interim result.
The balancing progress may be observed by monitoring the
Reject Power Percentage
meter.
Balancing targets a reject power percentage of 0.75% or less of the transmitter’s maximum
power capability. (An IPA Balancing Recommended alarm will be generated if this percentage
exceeds 1.5%.)
While this routine can be performed when operating in most presets (as the DAC bias numbers
are stored in the controller’s EEPROM), it should also be noted that this balancing process
affects only the active preset.
Users may also adjust the bias values individually to either a user specified value or to the
default value saved in that module’s EEPROM (see Factory Settings - PA Field Bias on page 2-
77 ). Note, that if an auto-balance is started any user set values will be replaced with default
values before the process starts. Therefore, manual adjustment should be undertaken only after
an auto-balancing has been completed or manually stopped.
Note:
IPA bias balancing cannot be performed when the transmitter is in the Current
Settings preset. Users must have an active preset saved (without edits) in order for
the updated IPA bias data to be stored properly. IPA bias balancing can also not be
performed if there is a module fault present (e.g. PA fail).