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HARRIS
888-9058-001
WARNING: Disconnect and lockout AC primary power prior to servicing
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controller circuit board. Add pads if needed to reduce the sample below the 4 volt
maximum to around 3 volts. In addition, if a 3 dB pad provides the correct voltage at TP
18, it’s important to add a 3dB pad to the reflected power sample line.
In a similar fashion actual reflected power can be calibrated. If there is no precision
reflected coupler, the furnished reflected coupler is reversed to meter forward power
and a 20 dB pad is added in series with the cable. (from our above example, you should
now have both a 3dB pad and a 20dB pad being used providing a total of 23 dB). Now
the reflected power can be calibrated at one percent of forward power. The reject loads
can be calibrated by turning off cabinets using the hybrid power division rules. Knowing
the theoretical reject power, then calibrate the reject power as a percentage of the reject
load power rating. Refer to Drawing 801-0210-011 sheet 13.
Once the proper reflected power calibration is done, the desired VSWR fault and
foldback values can be selected. VSWR control is software based and no further
calibration is needed. The actual operation can be checked by substitution of the
reflected signal. The RF signal level can be changed to verify operation. The VSWR
protection can be disabled as needed by the VSWR Protect button to make VSWR
calibration easier. This button has a time out function, five minutes after pushing, VSWR
protection will return to normal.
Figure 4-21 Output Tab, Service Button, System Aural Selected
This screen is used to calibrate the System Aural power metering and reject loads.
Use same procedure as System Visual above. The Aural Forward sample is measured at
TP20, and Aural Reflected at TP21. Refer to Drawing 801-0210-011 sheet 13.
