Yaesu FTDX-9000D, Operation Manual

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Page 62 FT
DX
9000D O
PERATION
M
ANUAL
ATT
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) 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.
Advice
If background noise causes the S-meter to deflect on clear frequencies, turn the ATT knob clockwise until the S-meter
drops to about “S-1.” This setting optimizes the trade-offs between sensitivity, 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.
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)
SUB(VFO-B)
ATT switch
MAIN(VFO-A)
ATT switch
MAIN(VFO-A) SUB(VFO-B)
C
ONVENIENT
F
EATURES