Comtech EF Data PCB-4000 - Manual (Page 35)

PCB-4000 1+1 Phase Combiner Revision 2
Installation, Startup, and Troubleshooting Procedures MN/PCB4000.IOM
3–7
3.4 Gain or Amplitude Balance Verification and Alignment
This procedure is generally not necessary if all parameters of Section 3.3 have
been met.
As a result of the configuration of the waveguide switches in a 1+1 system, it is possible to
measure the individual gain of each SSPA path by switching each SSPA individually to the output
load.
This procedure assumes that the output port is terminated and that data will be taken using the
Combined Output Power and Wasted Power Test Couplers (
Figure 3-1) .
Follow these steps:
Step Task
1
A. Attach a power meter to the Combined Output Power Test Coupler (Figure 3-1).
B. Apply a low-level signal at center frequency, making sure the output signal will be at least 10 dB below
Prated.
2
To measure only the individual gain of SSPA#1, SSPA#2 must by bypassed by changing the state of the
waveguide switches via remote control (for detailed remote command and query information, see Chapter
5. SERIAL REMOTE CONTROL):
A. Execute remote command RED=0;
B. Execute remote command BYP=2.
The output of SSPA#1 will be sent to the system output, while SSPA#2 will be muted and directed to the
“wasted” port.
3 Record the amplitude or gain level of SSPA#1.
4
Execute remote command BYP=1 to measure the individual gain of SSPA#2. This time, the output of
SSPA#2 will be sent to the system output, while SSPA#1 will be muted and directed to the “wasted” port.
5 Record the amplitude or gain level of SSPA#2.
6
Compare the levels of the two paths. Typically, the gains of each SSPA will be within ± 1 dB at center
frequency. If the above test is performed at other frequencies, it is reasonable to assume that the gain
difference may be greater.