Yaesu FT-1000MP Operating Manual page 34

Operation
IF Filter (Bandwidth) Selection
There are two banks of selectable filters, one
each for both the 8.215 MHz 2nd IF and 455 kHz
3rd IF in the Main Receiver. Filter selections can
be cascaded for versatility in combatting QRM
and tailoring received audio. From the factory,
500 Hz and 2.4 kHz filters are provided for the 2nd
and 3rd IF. Other filters can be ordered from your
Yaesu dealer. Installation instructions are covered
on page 100 and filter menu selections (5-0
through 5-7) on page 89. The illustration at the
bottom of the page provides a representation of
filter selection in the FT-1000MP.
Filters can be se- -——sanownorTH a
lected in pairs using the 8215 485 C_)
vertical buttons at the (250) (250) | 500 |
right, or else individu- Ee)
° . 2.0K) (2.0K) 2.0K
ally by first pressing jankf laa 4)
8.215 OF 455, then select- "24K
ing the filter from that C )sy
bank as desired. Inside | -8215 455. 8.0K
Coco CG
the bandwidth sub-
panel, two columns of
green indicators show the selected filter pair or
combination. Try the following example:
Ex. Select the 2.0K 2nd IF and 250 Hz 3rd IF filter.
OFirst press 8.215 (the left 8.215 column blinks)
then 2.0K. The green indicator shows 2.0K se-
lected in the left column.
J Next, press 455 so the right column now blinks,
then again press 250. The green indicator show
250 selected in the right column.
<
From 2nd Mixer
(8.215 MHz)
———_—_>
2.0 kHz
*
2.4 kHz
THRU
In AM mode, the 6-kHz AM wide bandwidth is
selected for both the 2nd & 3rd IF (labeled THRU
on the bottom of the 2nd IF column). This gives
the highest fidelity, and is best on strong AM
signals (and particularly music). The effects of the
SHIFT and WIDTH controls in this wide bandwidth
are subtle, but they can be helpful in fine tuning
the audio characteristics. For weaker AM signals,
or where adjacent channel interference is pre-
sent, the 2.4K bandwidth offers a compromise
between interference rejection and fidelity. In this
case the SHIFT and WIDTH controls can be used to
improve fidelity (see the illustrations).
However, even better reception of AM signals
under these conditions can usually be had by
switching to an SSB mode (whichever gives the
clearest reception), and superb reception of weak
signals is often possible using diversity reception,
described on page 46. In SSB modes, the 2.0K
bandwidth button can sharply cut interference
from unwanted signals on either side of the de-
sired signal (although with some necessary loss
of fidelity). In CW, the 2.0K or 2.4K bandwidth is
often convenient to give "a wide view" of the band
when tuning around, but once a signal of interest
has been found and centered in the passband,
the 500 or 250 (Hz) selections are much better.
In addition to selecting various filter combina-
tions, you have several features that can be used
singly, or in combination to eliminate or reduce the
interference to an acceptable level. Although their
use requires little more than rotating a control, it is
good to have knowledge on how each function
works and the effect on the QRM encountered.
455 —<
oo oa
eu ia Cc) wo
*k x
a)
J 6.0K
500 Hz Laall®
*
To 3rd IF Amp
(455 kHz)
2.0 kHz
re
* optional filter
Main Receiver (VFO-A) IF Bandwidth Filter Selections
page 32