Bird 4421 RF Power Meter
10
Error Codes
The Bird 4421 displays error codes when the RF power is either below the
selected range (underrange) or above the selected range (overrange). Table 4-1
displays the error codes and Table 4-2 lists the function limits.
Table 4-1 Error Codes
Table 4-2 Function Limits
Audible Warning
If the RF power level exceeds 120% of the power sensor’s maximum power
capability, the power meter will sound a warning buzzer.
Symbol
Explanation
Value greater than overrange limit of function
Value less than underrange limit of function
Function
Limit
Error
FWD, RFL
Power > 199.9% of full scale or 120% of
top range
Overrange
FWD dBm, RFL dBm
Power > 120% of full scale
Overrange
Power < 3% of low range
Underrange
SWR
FWD < 20% of low range
Underrange
FWD – RFL = 0
Overrange
Return Loss
FWD < 20% of low range
Underrange
RFL < 20% of low range
Underrange
Return Loss > 40 dB
Underrange
