Interference Rejection; R.flt (Roofing Filters) - Yaesu FTDX9000D - DATA MANAGEMENT Operation Manual

I R
NTERFERENCE EJECTION
Narrow-band Roofing Filters of 15 kHz, 6 kHz, and 3 kHz bandwidths are provided in the first IF, right after the first
mixer. These filters provide protection for the 2nd mixer, DSP, and other circuitry that follow and can dramatically im-
prove reception on a very crowded band (during a contest, etc.). Typically, the AUTO selection mode is satisfactory for
most operating situations, but in an extremely crowded phone band you may wish to select, for example, the 3 kHz roofing
filter for SSB operation.
MAIN (VFO-A) [ R.FLT ] switch
SUB (VFO-B) [ R.FLT ] switch
Main Band Roofing Filter Operation
Press the Main (VFO-A) band's [ R.FLT ] switch to
toggle the Roofing Filter selection.
AUTO 15 kHz
As you repeatedly press this switch, you will ob-
serve different LEDs lighting up in the Roofing Fil-
ter area of the front panel, denoting the Roofing Fil-
ter currently in use. Also, the selected Roofing Fil-
ter bandwidth will be indicated on the TFT.
Typically, this selection will be set to "AUTO."
The Roofing Filter selection will be memorized
independently on each VFO in the VFO stack.
Q Q Q Q Q
UICK UICK UICK
UICK UICK
The "AUTO" selection of the Roofing Filter is
based on the operating mode. However, you may
override the automatic selection, if band conditions
warrant a different (usually, a tighter) selection.
The AUTO mode Roofing Filter selections are
shown below:
AM/FM/FM-PKT
LSB/USB/PKT
CW/RTTY
FT 9000D O
DX PERATION
(S
IGNALS
R.FLT ( R
OOFING
6 kHz 3 kHz AUTO
P P P P P
OINT OINT OINT
OINT OINT
15 kHz
6 kHz
3 kHz
M
ANUAL
O F
FF REQUENCY BY
)
F
ILTERS
Roofing Filter bandwidth
will be indicated on the TFT
Sub (VFO-B) Band Roofing Filter Operation
1. Pressing the Sub (VFO-B) band's [ RX ] switch will
engage Dual Receive operation.
When the imbedded LED grows green, this is your
confirmation that Dual Receive is in operation.
2. Press the Sub (VFO-B) band's [ R.FLT ] switch to
toggle the Roofing Filter selection.
AUTO 15 kHz
As you repeatedly press the [ RX ] switch, the se-
lected bandwidth will appear on the TFT.
Typically, this selection will be set to "AUTO."
When "AUTO" is selected, the LED imbedded in
the switch will go out (there always is a roofing
filter in the receiver path).
The Roofing Filter selection will be memorized
independently on each VFO in the VFO stack.
T T T T T
ERMINOL ERMINOL ERMINOLOGY ERMINOL ERMINOL
A "Roofing Filter," as its name implies, places a
"Roof" over the receiver's IF system bandwidth.
This "Roof" protects the circuitry downstream
from the first mixer from interference, just as a
roof on a house protects the contents from rain and
snow.
J F
UST A EW KHZ
SUB (VFO-B) [ RX ] switch
6 kHz 3 kHz AUTO
OGY OGY OGY OGY
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