FT-950
Operating Manual
Vertex Standard Co., Ltd.
48
VFO-A and VFO-B.
On the 10 MHz and lower bands, it generally is not necessary to use any
preamplifier at all; selecting the “ON” position described above will increase the
strong-signal-handling capability of the receiver, and generally will result in more
pleasant reception due to reduced noise. If you can hear band noise with the
preamplifiers disengaged, then a preamplifier is generally not needed.
R.FLT (Roofing Filters)
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 selection.
AUTO 15 kHz 6 kHz 3 kHz AUTO
Advice:
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 independently on each VFO stack of
the VFO-A and VFO-B.
Quick Point:
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 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 bandwidth will automatically be set to 15 kHz, as this setting
provides the most effective noise blanking. However, you still may override the
