Nautel NX25, Operation And Maintenance Manual

Page: 17 / 162

NX300 Operations and Maintenance Manual Description
Issue 3.0 2012-11-01 Page 1-9
Figure 1.5: Cutback Recovery Time
Average reflected power foldback
If the average reflected power, calculated over a nominal 5 s period, exceeds a limit of 4% of rated
power, the output power is gradually reduced in order to maintain a reflected power that is less than
this limit. This gradual reduction in power into high VSWR allows the transmitter to continue to
operate into VSWR levels as high as 1.5:1 at full carrier power and even higher VSWR levels when the
carrier power is reduced. This VSWR protection is intended to protect against short or open circuits
when the transmitter is turned on, as well as non-transient faults such as a poorly tuned antenna
system.