Interference Rejection; Att - Yaesu FT DX 3000 Operating Manual

i
nTerFerence
When extremely strong local signals or high noise degrades reception, you can use the [ ATT ] button to insert 6, 12, or
18-dB of RF attenuation in front of the RF amplifier.
1. Press the [ ATT ] button several times to set the de-
sired attenuation level, per the chart below.
OFF: Attenuator is Off
-6dB: The incoming signal power is reduced by 6
dB (Signal voltage reduced by 1/2)
-12dB: The incoming signal power is reduced by 12
dB (Signal voltage reduced to 1/4)
-18dB: The incoming signal power is reduced by 18
dB (Signal voltage reduced to 1/8)
The selected attenuation level will be indicated in the
ATT column of the Block Diagram Display on the
TFT display.
2. To restore full signal strength through the Attenua-
tor circuit area, press the [ ATT ] button to restore the
ATT display to the "OFF" position.
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 The attenuator selection will be memorized independently on each VFO stack of the VFO-A and VFO-B.
 If background noise causes a high S-meter indication on clear frequencies, press the [ ATT ] button until the S-meter
drops to about "S-1". This setting optimizes the trade-off 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 (add more attenua-
tion) by pressing the [ ATT ] button to a higher 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 ] button should be set to "OFF."
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.
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ATT

[ ATT ] Button
Indicates the
attenuation level
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