Receiver Operation (Front End Block Diagram) - Yaesu FT DX 9000 CONTEST - MANUAL 2 Operation Manual

C
ONVENIENT
R
ECEIVER
The FT 9000 Contest includes a wide range of special features to suppress the many types of interference that may be
DX
encountered on the HF bands. However, real world interference conditions are constantly changing, so optimum setting of
the controls is somewhat of an art, requiring familiarity with the types of interference and the subtle effects of some of the
controls. Therefore, the following information is provided as a general guideline for typical situations, and a starting point
for your own experimentation.
We provide the RF -TUNING Unit (Narrow-bandwidth High-Q RF Filter) for the customized option..
VRF (See page 54)
On the HF/50 MHz Amateur bands, Yaesu's powerful VRF (Variable
RF Filter) preselector circuit provides excellent suppression of out-of-
band interference, with a passband much narrower than that provided
by traditional fixed bandpass filters.
R. FLT (IF Roofing Filters) (See page 55)
Three automatically-selected Roofing filters, in bandwidths of 15 kHz,
6 kHz, and 3 kHz, are provided in the 40 MHz First IF, right after the
first mixer. These filters provide narrow-band selectivity to protect the
following IF and DSP stages, and the filters' automatically-selected band-
widths may be manually changed by the operator, if desired, for special
operating circumstances.
CONTOUR Filter (See page 56)
The Contour filter is a unique capability of the FT
providing either nulling or peaking of tunable segments of the receiver
passband, so as to suppress interference or excessive frequency compo-
nents on an incoming signal, or to peak those tunable frequency seg-
ments. The amount of nulling/peaking, and the bandwidth over which
it is applied, are adjustable via the Menu.
IF SHIFT (See page 57)
The passband center frequency response of the IF DSP filtering may be
adjusted using this control.
IF WIDTH (See page 58)
The width of the IF DSP filtering may be carried using this control.
IF NOTCH (See page 59)
The IF Notch filter is a high-Q notch filter that can significantly reduce,
if not eliminate, an interfering carrier. The Q (sharpness) of the filter
may be adjusted using the Menu.
OPTION
µ-TUNE
VRF
VRF
OPTION
Page 50
F
EATURES
( F
O
PERATION RONT
9000 Contest,
DX
Main Band ( VFO-A )
RF
IPO "OFF"
BPF RF AMP
1st Local
Sub Band (VFO-B)
RF
IPO "OFF"
BPF RF AMP
1st Local
FT
E B D
ND LOCK
NR (Digital Noise Reduction) (See page 60)
The DSP's Digital Noise Reduction (DNR) feature utilizes sixteen dif-
ferent mathematical algorithms to analyze and suppress different noise
profiles encountered on the HF/50 MHz bands. Choose the selection
that provides the best noise suppression, which concurrently will allow
the signal to rise up out of the noise.
D.NOTCH (Digital Notch filter) (See page 62)
When multiple interfering carriers are encountered during reception, the
Digital Notch Filter can significantly reduce the level of these signals.
AGC (See page 63)
The AGC system is highly adaptable to changing signal and fading char-
acteristics, making reception possible under the most difficult conditions.
SLOPED AGC (See page 64)
The Sloped AGC system, instead of clamping a fixed upper bound on
audio output across a wide range of input signals, actually allows the
audio output to rise, very gently, with ever-increasing signal strength.
This capability allows you to separate signals, using your brain, accord-
ing to signal strength in addition to slight frequency differences.
IF Filter Quality Adjustment (See page 124)
The "Q" (quality factor) of the IF DSP filters may be adjusted indepen-
dently for the IF DSP filters, using the Menu.
Variable IF Filter Shape Factor (See page 124)
You may adjust the shape factor of the IF DSP filters, using the Menu.
1st IF
40.455 MHz
ROOFING
FILTER
1st
CF
IF AMP
3k/6k/15k
2nd Local
1st IF
40.450 MHz
ROOFING
FILTER
1st
CF
IF AMP
3k/6k/15k
2nd Local
9000 C
DX ONTEST
)
IAGRAM
2nd IF 3rd IF (DSP)
455 kHz 30 kHz
2nd DSP
IF AMP UNIT
3rd Local
2nd IF 3rd IF (DSP)
450 kHz 30 kHz
2nd DSP
IF AMP UNIT
3rd Local
O M
PERATION ANUAL