Yaesu FT-991 Operating Manual page 49

The FT-991 includes an effective IF Noise Blanker, which can significantly reduce noise caused by automotive ignition
systems.
1. Press the F(M-LIST) button to display the function
menu list. Touch the [ NB ] function icon briefly to
reduce short duration pulse noise like that from
switching transients, automobile ignitions and power
lines. The Noise Blanker will be set to "ON".
1. Press the MENU button to engage the Menu
mode.
2. Rotate the MULTI knob to select Menu item "025
NB LEVEL".
3. Touch [ SELECT ] on the LCD
4. Rotate the MULTI knob to the point where the
offending noise is best reduced or eliminated.
5. Touch [ ENTER ] on the LCD, then press the
MENU button or touch [ BACK ] on the LCD to
lock in the new setting and exit to normal opera-
tion.
FT-991 O
peraTing
i
nterference
iF n b
oiSe lAnker
Adjusting the Noise Blanker Level
M
anual
( nb ) o
perAtion
F(M-LIST) Button
2. If desired, the Noise Blanker level may be adjusted
via Menu item "025 NB LEVEL" to the point where
the offending noise is best reduced or eliminated.
See box below for details.
A :
dvice
 The noise attenuation can be selected from
10dB/30dB/50dB via Menu item "024 NB RE-
JECTION".
3. To end Noise Blanker operation, touch [ NB ] on the
TFT display once more. The "OFF" will appear in
the TFT display, confirming the Noise Blanker is no
longer in operation.
MENU button
MULTI Knob
r
eJection
Page 47