______________________________________________
HARRIS
888-9058-001
WARNING: Disconnect and lockout AC primary power prior to servicing
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The following things can be done to help in the VSWR fault checking.
•
To check the fault point without foldback interaction, simply set the foldback
point to a higher value than the desired fault point. After checking, remember to set
the foldback to the desired lower point.
•
A quick check of foldback can be done simply by setting the foldback to a value
slightly lower than the actual VSWR. This would trigger a foldback event, GUI
should indicate that foldback is occurring and the output power will be a lower
value.
•
There is a button on this page that will turn off the VSWR control actions
including any VSWR indicators. This button will time out in 5 minuets and VSWR
control will return to normal. Turning off the VSWR control will allow RF levels or
trip points to be reached without any change in transmitter output power.
2.19 Aural VSWR Calibration
VSWR calibration follows forward and reflected power calibration. The VSWR foldback
will limit the reflected power to a fixed value.
The VSWR foldback will limit the reflected power to a fixed value, the 1.22:1 value is 1%
of the normal forward power. An example is a 2 cabinet PA that has a normal forward
power of 6.2 KW. The foldback will limit the reflected power to 62 Watts. The second line
of protection is the module internal VSWR protection. Modules will always VSWR protect
using the module logic.
IF you have confidence in the power calibration, you can let the software use the default
values of 1.22:1 as the foldback fault point and 1.40:1 for VSWR fault. Other values can be
entered from the Output tab, service screen. If you want to verify operation, substitute a
variable level RF source for the reflected sample such the output of the back-up exciter and
increase the level to check the foldback point.
The following things can be done to help in the VSWR fault checking.
•
To check the fault point without foldback interaction, simply set the foldback
point to a higher value than the desired fault point. After checking, remember to set
the foldback to the desired lower point.
•
A quick check of foldback can be done simply by setting the foldback to a value
slightly lower than the actual VSWR. This would trigger a foldback event, GUI
should indicate that foldback is occurring and the output power will be a lower
value.
•
There is a button on this page that will turn off the VSWR control actions
including any VSWR indicators. This button will time out in 5 minuets and VSWR
control will return to normal. Turning off the VSWR control will allow RF levels or
trip points to be reached without any change in transmitter output power.