Page 47
FT-
991
Operating Manual
ATT
(
Attenuator
)
When the desired signal is extremely strong or the noise level is high on a low frequency band, activate the attenuator to
reduce the incoming signal from the antenna.
1. Press the
F
(M-LIST)
button, then touch [
ATT
] on
the LCD. The “
ATT
” indicator will appear in the
DSP display.
Advice:
The incoming signal level is reduced by 12dB
(Signal voltage is reduced to 1/4 compared to OFF).
F(M-LIST) Button
Displays ATT
2. To restore full signal strength through the Attenuator
circuit, touch [
ATT
] on the LCD to return the ATT
display to the “
OFF
” position.
Advice:
If the noise level is high or the received signal is extremely strong, the incoming signal level can be suppressed with the
IPO/ATT settings.
If the S-meter fluctuates S-3 or more in the noise level, or the received signal is extremely strong and it causes a high S-
meter indication (
+20dB or more
), activate the attenuator.
Since IPO does not only attenuate the incoming signal, but also improves the cross modulation characteristic, try to ac-
tivate the IPO first. If the signal is still strong, also use the ATT. In this way, you can attenuate the incoming signal and
noise effectively.
Interference Rejection
