Interference Rejection (Signals Off Frequency By Just A Few Khz); R.flt (Roofing Filters) - Yaesu FT-2000D Operating Manual

I
NTERFERENCE
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 fort 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.
Press the [ R.FLT ] button to toggle the Roofing
Filter selection.
AUTO AUTO AUTO AUTO AUTO 15 kHz 15 kHz 15 kHz 15 kHz 15 kHz 6 kHz 6 kHz 6 kHz 6 kHz 6 kHz
A :
DVICE
The Roofing filter selection affects the Main band
(VFO-A) only. The Sub band's (VFO-B) Roofing fil-
ter is fixed at a bandwidth of 15 kHz.
As you repeatedly press the [ R.FLT ] button, you will
observe changes in the notation in the R.FLT column
of the Receiver Configuration Indicator on the display,
denoting the
Roofing Fil-
ter currently
in use.
Typically, this selection will be set to "AUTO
The Roofing Filter selection will be memorized inde-
pendently on each VFO in the VFO stack.
Q P :
UICK 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: 15 kHz
LSB/USB/PKT:
CW/RTTY:
T :
ERMINOLOGY
A "Roofing Filter," as its name implies, places a "Roof"
over the receiver's IF system bandwidth. This "Roof" pro-
tects the circuitry downstream from the first mixer from
interference, just as a roof on a house protects the contents
from rain and snow.
Page 54
R
EJECTION ( S
R.FLT ( R
3 kHz 3 kHz 3 kHz 3 kHz 3 kHz AUTO AUTO AUTO AUTO AUTO
AUTO AUTO AUTO." AUTO
6 kHz
3 kHz
O F
IGNALS FF REQUENCY BY
)
F
OOFING ILTERS
Receiver Configuration Indicator
[ R.FLT ] Button
FT-2000D O
)
J F
UST A EW KHZ
M
PERATING ANUAL