Filter
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J SELECTIVITY switch
When an optional filter is installed, the receiver's passband
can
be switched to one of four different bandwidths by us-
ing the SELECTIVITY switch.
The
switch has five positions; AUTO, N, M 1, M2 and W,
that
are used to select the bandwidth. This switch should
normally be set to the AUTO position. The IF bandwidth
will then be selected for optimum receiver characteristics,
according to the MODE that has been selected. Manual
override is possible by simple rotation of the SELECTIVITY
switch.
The table on page 16 shows the bandwidth of each switch
setting. Note the differences when the optional filters are
installed.
Caution:
Optional filter should be installed by qualified service per-
sonnel to prevent personal injury or damage to the equip-
ment.
Note:
When in the FM mode the bandwidth is always 12kHz, re-
gardless of the position of the SELECTIVITY switch.
®
SQL (Squelch) control
This control is used to eliminate atmospheric noise, and
receiver static noise during no signal periods. Slowly ro-
tate the control clockwise to the point where the ambient
noise just disappears, and speaker shuts off. This point is
known as the squelch threshold point. Now you will only
hear output from the speaker when an incomming signal is
present. For weak signal reception this control should be
fully counterclockwise.
Note:
The squelch threshold position will vary from mode to
mode, so you may have to readjust when you change
mode.
®
NOTCH control
The NOTCH function is used to reduce or eliminate hetero-
dyne, or CW type signal interference.
If a single tone such as a CW signal is superimposed on
the receive signal, turn the NOTCH switch ON and slowly
adjust the NOTCH control to eliminate or minimize the
beat signal. Normally the NOTCH point will occur between
11:00 and 1:00.
The NOTCH filter will not be effective against SSB, AM or
FM type signals, only single tone CW type signals.
In the CW mode, an audio peak filter (APF) is automatically
selected; adjust the NOTCH control for the best signal.
In CW, we recommend the use of a CW filter (YK-88C or
YK-88CN). When a CW filter is installed, the APF is dis-
connected.
Whithout a CW filter installed, APF is connected in CW
mode. The APF works in similar fashion as a CW filter.
Note:
The NOTCH function is used to reduce or eliminate hetero-
dyne, or CW type signals.
®
I F SH I FT control
The IF SHIFT control allows you to shift the IF passband of
the receiver, without changing the actual center frequency
of the receiver. This control is useful when there is inter-
ference near your center frequency.
Interference from lower frequencies can be reduced or eli-
minated by rotating the IF SHIFT control clockwise. This
will cause the resulting audio frequencies to have a slightly
treble response, i.e. low cut filter (low frequencies atten-
uated). Interference from higher frequencies can be re-
duced or eliminated by rotating the IF SHIFT control
counterclockwise. This will cause the resulting audio frequen-
cies to sound a little bassy, i.e. high cut filter (high frequen-
cies attenuated).
Note:
The IF SHIFT control does not function in the AM or FM
modes.
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