Comtech EF Data PCB-4300 - Manual (Page 41)

PCB-4300 1:2 Phase Combiner Revision 2
Operation and Adjustment Procedures MN/PCB4300.IOM
3–11
5 Measure the gain (or output level) of each individual SSPA at the start, middle, and stop
frequencies of the amplifier band by using serial remote command FRC= to alternately
send the output of each SSPA to the Offline Test Port Coupler.
The table that follows is intended as a worksheet to help equalize the gains. (Note that
the AOF level can be queried via serial remote command (where X=PCB-
4300 address, and Y=1, 2, or 3 – the individual SSPA offset in question.)
Offline
SSPA ‘FRC=’
Setting
AOF Value
Measured Output Level (dBm)
F
strt
= F
mid
= F
end
=
1 23 AOF#1=_____________ ________ ________ ________
2 13 AOF#2=_____________ ________ ________ ________
3 12 AOF#3=_____________ ________ ________ ________
6 If necessary, fine-tune the offsets of one or more of the SSPAs to achieve
equalization. Record the final offsets and output levels in the above table. (The offsets
are adjusted by the serial remote command (where X=PCB-4300
address; Y=1, 2, or 3 – individual SSPA offset in question; and Z.ZZ=desired offset
level).
For example, if it is desired to set the offset level of AOF#3 to 3.75 dB, and the PCB-
4300 address is 1, then serial remote command <1/AOF=3,3.75 should be sent.
3.5.2 Phase Equalization
Once the amplitudes have been equalized across the frequency band, the phase paths can be
aligned. This is accomplished by adjusting the two phase shifters inside the PCB-4300 box (see
Figure 3-4), using the Phase Shifter Adjustment Tool Kit, such that the Combined Output Power
Level is maximized and the “Wasted” Output Power Level is minimized.
Referring to the block diagram in Figure 1-2, there are two phase shifters:
• The phase shifter in the path to SSPA#1 are used to equalize the phase between SSPAs
#1 and #2;
• The phase shifter in the path to SSPA#3 is used to equalize the phase between SSPAs #3
and #2.
Since they were equalized to a “reference” (i.e., #2),by default SSPAs #1 and #3 will be equalized
to each other.
Observe the following:
Step Procedure
7 Attach one channel of the power meter to the Combined Output Power Test Coupler
(refer to Figure 3-1). Attach the second channel of the power meter to the “Wasted”
Power Test Coupler. Make sure the power meter has been appropriately calibrated to
include the respective correction factors of the test port couplers.
Note: If only one power meter is available, it may be alternately switched between the
Combined Output Test Coupler and the Wasted Test Coupler. It is suggested to start
with it at the Wasted Test Port as the power level at this port will be more sensitive to
adjustment.