Bird Technologies ACM Series-Manual - Manual (Page 30)

Bird Technologies
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VSWR Alarm - Adjustable from 1.3 to 2.5 by increments of 0.1. To
allow the VSWR alarm to trigger even at low forward power (< 2.5% of
full scale power), check the “Alarm on Zero Power” checkbox.
While the VSWR trip point can now be set out to 2.5, the instrument
cannot always measure VSWR above 1.9. This is due to the large
amount of reflected power caused at higher VSWRs. The maximum
VSWR that can be physically measured is determined by the full scale
ratio of the forward and reflected detectors. This ratio is 10:1. The
maximum measurable VSWR occurs when the reflected channel is
near its limit. The following table shows the maximum possible VSWR
measurement as a function of percentage of full scale forward input
power. Use this table as a guide to determine the VSWR trip point.
High Power Alarm - Adjustable from 0 to 125% of the ACM’s full scale
power. The alarm setpoint is entered as the % of full scale.
Example - A 100W full scale unit and an alarm is needed
when the forward power exceeds 75 W, the alarm setpoint
would be 75 /100 x 100 or 75%. Enter “75” into the data field
and check the “Enable High Power Alarm” checkbox.
Low Power Alarm - Set in the same way as the High Power Alarm,
however this alarm will trigger when the forward power is less than
the alarm setpoint.
Percentage Full
Scale
Max VSWR
50% 3.00
55% 2.82
60% 2.68
65% 2.56
70% 2.46
75% 2.38
80% 2.31
85% 2.24
90% 2.19
95% 2.14
100% 2.09