Comtech EF Data PCB-4300 User Manual
Page 42
PCB-4300 1:2 Phase Combiner
Revision 2
Operation and Adjustment Procedures MN/PCB4300.IOM
3–12
8
Align the phase between SSPA#1 and #2:
• First, execute serial remote command FRC=12.
• Referring
to
Figure 3-4, use the provided tool to loosen the locknut on the
phase shifter for path 1-2. Slowly turn the phase shifter with the screwdriver
while viewing the Combined and Wasted Power readings. Toggle back and
forth between the Start, Middle, and Stop frequencies to maximize the
difference (ratio) between the Combined Power and the Wasted Power. The
ratio generally needs to be balanced at the endpoints, and will usually be
greater at the center frequency.
Note: For broadband operation, (a) the difference between Combined and Wasted
Power levels will be 10-20 dB or more, and (b) there may be two different positions of
the phase shifter which give good results at the center frequency, but there is only one
position which will give the broadest band operation – i.e., which gives the best
difference between the combined and wasted power levels at all frequencies.
9
Align the phase between SSPA#3 and #2:
• First, execute serial remote command FRC=23.
• Referring
to
Figure 3-4,
adjust the phase shifter for path 2-3 as was done for
path 1-2 in Step 8.
10
After aligning paths 1-2 and 2-3 per Steps 8 and 9, execute serial remote command
FRC=13 to combine SSPAs #1 and #3. The Combined and Wasted level ratios should
be similar to those for the other paths mentioned above. Then:
• Perform any necessary fine adjustments, toggling between all three paths until
satisfactory performance is achieved. It may be necessary to slightly “skew”
the combined/wasted power ratio over frequency to achieve best system
performance at a band edge.
• Tighten all phase shifter adjustment nuts with the provided socket.
• Replace the cover over the access hole.
Note: The Wasted Power Level is more sensitive, but optimizing it beyond reasonable
values has a diminishing effect on the desired Combined Output Power.