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Dealing
with
Interference
Operation
you gain several benefits of the
SHIFT
control.
After selecting the best sideband (LSB or USB
mode), you need to zero beat the carrier to avoid
distortion: turn the
SHIFT
control all the way
clockwise for LSB or counterclockwise for USB,
fine tune until the signal is steady, then return
the
SHIFT
control to center (or for best audio and
interference suppression).
YF-101 SSB Crystal Filter Option
The optional YF-101 crystal IF filter can be
installed in place of the 2.4-kHz ceramic IF
filter, to enhance SSB and AM narrow recep-
tion. While both filters have approximately
the same shape factor and bandwidth, the
crystal filter provides a flatter passband, giv-
ing receiver audio a more natural sound, and
also deeper attenuation for better immunity
to interference from nearby signals. Typical
plots of the two filters are superimposed be-
low for comparison. Ask your dealer for the
YF-101 option if you don't have it. Installa-
tion is described beginning on page 36.
453
455
457
k H z
/<Hz
kHz
10-Hz Steps in AM
&
FM Modes
When changing modes from SSB or
CW
to
AM or FM, operation initially remains on the
same frequency, even if it is not a multiple of
100 Hz. As soon as you attempt to tune, the
operating frequency jumps up or down to the
nearest whole 100-Hz step. However, the
clarifier uses 10-Hz steps in all modes, so if
you need 10-Hz resolution in AM or FM
mode, activate the clarifier (see page 21).
Pressing the CW mode button once when
switching from another mode selects the 2.4-kHz
IF bandwidth also used for SSB. If you have
either the 250-Hz or 500-Hz narrow IF filter in-
stalled, pressing the CW button again selects the
narrow filter, and
"NAR"
appears at the top of the
display. The 2.4-kHz bandwidth is often conven-
ient to give "a wide view" when tuning around,
but once you find a signal of interest and center
it in the passband, the narrow selection is much
better. The next section on transmission gives
more details of CW operation.
IF Notch Filter
(not used
in FM mode)
After tuning in a desired signal and adjusting
the IF shift, if you hear heterodyne interference,
activate the IF notch filter by pressing the
NOTCH
button/LED and adjusting the control with the
same name to null the heterodyne. Note that if
the interfering heterodyne is more than about 1.2
kHz away from the center of the passband, the
notch filter may be unable to null it. Try switch-
ing the notch filter off and readjusting the
SHIFT
so that the heterodyne is outside the passband.
Heterodyne
\
Signal
I
IF
Bandpass
1
IF Notch Filter Adjustment
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page I 6
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