Yaesu FT DX 9000D - COMPUTER AIDED TRANSCEIVER, Operation Manual

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Page 24 FT
DX
9000D O
PERATION
M
ANUAL
NB Switch
Pressing this button activates the (analog) IF Noise
Blanker, which may help reduce many different types
of man-made impulse noise (but not atmospherics).
When the Noise Blanker is activated, the LED inside
the button will glow red. Adjustment of the Noise
Blanker level is accomplished via the NB knob, de-
scribed in the previous section.
VRF/µ-T Switch
This button turns the main band (VFO-A) receiver’s
VRF filter or µ-TUNE filter on and off. While acti-
vated, the LED inside the button will glow red.
VRF/µ-T/NTCH Knobs
VRF/µ-T Knob
The inner VRF/µ-T knob tunes the passband of the
main band (VFO-A) receiver’s RF filter (18 MHz and
higher Amateur bands) or µ-TUNE filter (Narrow-
bandwidth High-Q RF Filter) (14 MHz and lower
Amateur bands) for maximum receiver sensitivity (and
out-of-band interference rejection). On the 18 MHz
and higher Amateur bands, this knob provides adjust-
ment of the VRF (Variable RF Filter) preselector cir-
cuit.
Advice
H
It is possible to use the Menu to de-select the µ-
Tune module, and utilize VRF instead, on bands
where a µ-Tune module is installed. However, the
superior selectivity of the µ-Tune circuit is pre-
ferred for most applications.
H
The µ-Tune circuitry automatically tracks your op-
erating frequency, and adjustment of its center fre-
quency is normally not required. However, if a
very strong signal within several dizen kHz is
causing you problems, you may use the VRF/µ-
T / NTCH knob to skew the tuning to one side
of the other of your current frequency, to roll off
the strength of the interfering station.
H
If you wish to reset the tuning of the VRF/µ-T /
NTCH knob to its original (centered) setting,
just press and hold in the VRF/µ-T switch (#
above) for two seconds. The µ-Tune circuit will
not revert to its normal (automatically tuned) po-
sition, centered on your current frequency.
H
There is a slight increase in receiver path insertion
loss when the µ-Tune circuit is engaged. On the
frequencies where µ-Tune is used, this is seldom a
problem. If the slight signal loss presents a prob-
lem, just turn the VRF/µ-T switch (#
above)
Off.
H
Rotation of the VRF/µ-T / NTCH knob to
adjust the µ-Tune circuit should be performed only
to optimize the signal or reduce interference. The
µ-Tune circuit tuning is surprisingly sharp. If you
are adjusting VRF, however, the tuning is much
more broad, and we believe that VRF adjustment
will seldom be required.
H
The relative position of the µ-Tune or VRF pass-
band can be observed on the TFT display.
NTCH Knob
The outer NTCH knob adjusts the center frequency
of the main band (VFO-A) IF notch filter. The Notch
Filter is engaged via the NTCH switch, described
in the next section.
F
RONT
P
ANEL
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ONTROLS