Att - Yaesu FTDX9000D - DATA MANAGEMENT Operation Manual

Even with the IPO function on, extremely strong local signals or high noise can still degrade reception. In such situations,
you can use the [ ATT ] knob to insert 3, 6, 12, or 18-dB of RF attenuation in front of the RF amplifier.
MAIN (VFO-A) [ ATT ] switch
SUB (VFO-B) [ ATT ] switch
Main (VFO-A) Attenuator Setup
Rotate the Main (VFO-A) side's [ ATT ] switch to set the
desired attenuation level, per the chart below.
To restore full signal strength through the Attenuator cir-
cuit area, set the [ ATT ] switch to the "0" position.
Sub (VFO-B) Attenuator Setup
Rotate the Sub (VFO-B) side's [ ATT ] switch to set the
desired attenuation level, per the chart below.
To restore full signal strength through the Attenuator cir-
cuit area, set the [ ATT ] switch to the "0" position.
0 dB Attenuator is Off
3 dB The incoming signal power is reduced by 3 dB (signal volt-
age reduced by 1/1.4)
6 dB The incoming signal power is reduced by 6 dB (signal volt-
age reduced by 1/2)
12 dB The incoming signal power is reduced by 12 dB (signal volt-
age reduced by 1/4)
18 dB The incoming signal power is reduced by 18 dB (signal volt-
age reduced by 1/8)
FT 9000D O
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ATT

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If background noise causes the S-meter to deflect
on clear frequencies, turn the [ ATT ] knob clock-
wise until the S-meter drops to about "S-1." This
setting optimizes the trade-offs between sensitiv-
ity, noise, and interference immunity. Also, once
you have tuned in a station you want to work, you
may want to reduce sensitivity further (or add more
attenuation) by turning the [ ATT ] knob to a more
clockwise setting. This reduces the strength of all
signals (and noise) and can make reception more
comfortable, important especially during long
QSOs.
When looking for weak signals on a quiet band,
you will want maximum sensitivity, so the IPO
should be disabled and the [ ATT ] knob should be
set to "0". This situation is typical during quiet
times on frequencies above 21 MHz, and when
using a small or negative-gain receiving antenna
on other bands.
F
EATURES
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