Harris Atlas DVL400, Technical Manual

Page: 151 / 180

2/25/03 888-2473-001 5-5
WARNING: Disconnect primary power prior to servicing.
Section 5 Maintenance and Alignments
ATLAS Series™
5.4 PA Module Phasing
Due to the use of a hybrid combining system, each pair or group of modules being
combined has a 90
o
relationship. This requires adjustment to the phase of individual
modules and module groups while watching the power at each of the reject loads and
adjusting for a minimum reading. Once this is done at a particular operating frequency,
it should not need to be re-adjusted except on an annual or semi-annual basis to
optimise the transmitter efficiency. Access Figure 5-4 as follows:
NOTE:
Before adjusting the module phasing to reduce the reject load power, check
the power output of the PA modules to make sure they are all producing
approximately the same power level.
Figure 5-4 PA Module Phasing Screen
The detected RF samples from each of the combiner reject loads are shown as A/D
readings or numbers from 0000 to 1023, with 0000 being ideal and 1023 being the
worst case condition. These numbers are shown below the bargraphs in Figure 5-4.
5.4.1 Phase Control Voltage
Each module has a Phase number at the bottom of the screen which has a range of
0000 to 1023, with 0512 being the ideal. This is a reference number which is
relative to the phase control voltage used to adjust the module phase. This number
will change as the Phase /- buttons are pressed. There is no correct value for
this number. It is just a reference to allow the operator to see the changes being
made and how far he has gone in a particular direction. However, it is always going
to be better if the number is close to center to give maximum adjustment range
when needed. Final phasing is based on reject power, not the phase number.
Key Presses
Detected rf sample
level, 0000 - 1023
PA Module Phase
Control Voltage
0000 - 1023
GOAL: To get the
detected rf sample
level readings
below 0030 (with
Gain set to LOW)
Module Group
select buttons
Reject Loads