Interference Rejection; R.flt (Roofing Filters) - Yaesu FT DX 9000MP Operation Manual

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 improve
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.
SUB(VFO-b)
[R.FLT] Switch
( VFO-A ) R
M B
AIN AND OOFING
Press the Main (VFO-A) band's [ ROOFING ] switch
to toggle the Roofing Filter selection.
AUTO 15kHz 6kHz
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 Filter
bandwidth will be indicated on the LCD display.
Typically, this selection will be set to "AUTO."
The Roofing Filter selection will be memorized
independently on each VFO in the VFO stack.
( VFO-B ) R
S B
UB AND OOFING
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 [ FLT ] switch to toggle
the Roofing Filter selection.
AUTO 15kHz
As you repeatedly press the [ FLT ] switch, the se-
lected bandwidth will appear on the LCD display.
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.
FT 9000MP O
DX PERATION
I I I I I R R R R R
NTERFERENCE NTERFERENCE NTERFERENCE EJECTION EJECTION EJECTION
NTERFERENCE NTERFERENCE EJECTION EJECTION
R.FLT ( R
OOFING
Roofing Filter bandwidth will be indicated on the LCD
MAIN(VFO-A)
[ROOFING] Switch
F O
ILTER PERATION
3kHz AUTO
F O
ILTER PERATION
6kHz 3kHz AUTO
M
ANUAL
(S (S (S (S (S O O O O O F F F F F
IGN IGN ALS ALS FF FF FF FF FF REQ REQ UENCY UENCY UENCY BY BY BY BY BY
IGN IGNALS IGN ALS ALS REQ REQUENCY REQ UENCY
)
F
ILTERS
VDD
Roofing Filter bandwidth will be
indicated on the LCD
Q Q Q Q Q P P P P P
UICK UICK UICK UICK UICK OINT OINT OINT OINT OINT
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
T T T T T
ERMINOL ERMINOL
ERMINOL ERMINOLOGY 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 J J J J F F F F F ) ) ) ) )
UST A A A A A UST UST EW EW EW EW EW KHZ KHZ KHZ
UST UST KHZ KHZ
BIAS TEMP SWR
15kHz
6kHz
3kHz
OGY OGY
OGY OGY
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