R.flt (Roofing Filters) - Yaesu FT-950 Operating 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.
Press the [ R.FLT ] button to toggle the Roofing Filter se-
lection.
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
As you repeatedly press the [ R.FLT ] button, you will
observe changes in the notation in the R.FLT column
of the Block Diagram Display on the display, denoting
the Roofing Filter currently in use.
Typically, this selection will be set to "AUTO."
The Roofing Filter selection will be memorized inde-
pendently on each VFO stack of VFO-A and VFO-B.
B D
LOCK IAGRAM
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:
O M
PERATING ODE
"AMP 1"
AM/FM/FM-PKT 15 kHz
LSB/USB/PKT 6 kHz
CW/RTTY 3 kHz
When the Roofing filter mode is set to "AUTO" and
the Noise Blanker is turned On, the Roofing Filter band-
width will automatically be set to 15 kHz, as this set-
ting provides the most effective noise blanking. How-
ever, you still may override the automatic setting, and
select a narrower Roofing Filter. Noise blanking may
be compromised, however, with a tighter Roofing Fil-
ter in the line.
FT-950 O
PERATING
I
R.FLT ( R
AUTO .....
3 kHz 3 kHz 3 kHz 3 kHz 3 kHz AUTO AUTO AUTO AUTO
D
ISPLAY
IPO S
WITCH
"AMP 2" "ON"
15 kHz 15 kHz
15 kHz 6 kHz
15 kHz 3 kHz
M
ANUAL
NTERFERENCE
)
F
OOFING ILTERS
Block Diagram Display
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.
R
EJECTION
[ R.FLT ] Button
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