Yaesu FT-2000D, Operating Manual

Page: 56 / 140

Page 54 FT-2000D O
PERATING
M
ANUAL
R.FLT
(
R
OOFING
F
ILTERS
)
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.
I
NTERFERENCE
R
EJECTION
(
S
IGNALS
O
FF
F
REQUENCY BY
J
UST A
F
EW KHZ
)
Press the [
R.FLT
] button to toggle the Roofing
Filter selection.
AUTO AUTO
AUTO AUTO
AUTO
Æ
15 kHz 15 kHz
15 kHz 15 kHz
15 kHz
Æ
6 kHz 6 kHz
6 kHz 6 kHz
6 kHz
Æ
3 kHz 3 kHz
3 kHz 3 kHz
3 kHz
Æ
AUTO AUTO
AUTO AUTO
AUTO
A
DVICE
:
ˆ 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.
ˆ 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.
ˆ Typically, this selection will be set to “
AUTO AUTO
AUTO AUTO
AUTO
.”
ˆ The Roofing Filter selection will be memorized inde-
pendently on each VFO in the VFO stack.
Q
UICK
P
OINT
:
ˆ 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.
ˆ The AUTO mode Roofing Filter selections are shown
below:
AM/FM/FM-PKT: 15 kHz
LSB/USB/PKT:
6 kHz
CW/RTTY: 3 kHz
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.
Receiver Configuration Indicator
[R.FLT] Button