Sangean ATS-405 Manual page 25

Set the AGC (auto gain control)
In AM band (MW and SW), if the volume level
changes too rapidly during listening, you can delay the
responding by setting AGC IF (intermediate frequency)
gain
1. AGC is for AM (MW/SW) only
2. AGC function is set the IF(intermediate frequency)
gain, it has 3 selection by 50db/auto/30db
2- "Auto" selection is the defaulted AGC level which
has a balanced gain for reception, recommended
set on auto for general purpose.
2-2 select 50 db to have a higher IF gain than the "auto",
it can amplitude weak signal 0dB more than auto,
the background noise will be enlarged, but easy to
make the signal saturate under a stronger signal.
In addition the soft mute may not be active because
of more background noise.
2-3 choose 30db to have a lower IF gain then the
"auto", once if you prefer to receive the stronger
signal only, reducing the IF gain is able to reject
the weak signal and background noise.
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