Buick LeSabre 1965 Service Manual page 736

ACCESSORIES
RADIO AND ANTENNA 1 1 - 3
front and rear speakers together,
and the counterclockwise position
turns on the front speaker only.
After the volume has been set by
the radio volume control, it will
remain constant regardless of the
position of the r e a r speaker
control.
c. Push Button Tuning
Operation—Wonderbar
or Sonomatic
To tune in the station for which
the push button is set, simply
push the button in as far as pos-
sible. The button will move easily
at the start, then a slightly harder
push is required to complete the
travel. At end of button travel
the tuner will rest at the station
for which the button has prev-
iously been set as described in
paragraph 11-4 (b).
d. Selective Tuning
Operation—Wonderbar
Radio
NOTE: To insure adequate sen-
sitivity for selective tuning of the
Wonderbar radio it is best to have
at least half
antenna extended
way.
With the radio turned on and
warmed-up, selective tuning of
available stations is accomplished
by depressing the selector bar
above the dial.
When the bar switch is fully de-
pressed and released the tuner
will automatically move to the
right and stop accurately tuned,
as it reaches the next station hav-
ing adequate strength to stop it.
The tuner will stop at a station
having adequate strength even
though the volume control is not
turned up high enough for the
station to be audible.
When the tuner reaches the right
end of the dial it flies back to the
left end and again starts moving
to the right until it again reaches
a station having sufficient strength
to stop it. By holding the selec-
tor bar down, unwanted stations
or areas of the dial can be quickly
passed over.
The number of stations on which
the tuner will stop in selective
tuning is regulated by manual set-
ting of the sensitivity control (see
Figures 11-1 and 11-2). This is
a step control having three po-
sitions. This control is in the
circuit only while the tuner is
seeking and does not affect the
"on station
7;
sensitivity of the
receiver.
Moving the sensitivity control
lever to the right position in-
creases the number of stations
that can be received. Moving the
control lever to the left decreases
the number of stations by elimi-
nating those having weak signal
strength in the area where the car
is located. In the full left position
of the control, the tuner will
usually stop only on strong local
stations.
If the Wonderbar tuner is oper-
ated in certain shielded localities
or around buildings where an ade-
quate signal is not available, the
tuner may automatically search
the band from one end to the other
without stopping. The sensitivity
control should be moved to the
full right position and the antenna
fully extended when this condition
is encountered, or manual tuning
should be used.
e. Manual Tuning Operation
The manual tuning knob is to the
right of the dial. This knob may
be used to tune in stations other
than those for which the push but-
tons are set; it is also used when
tuning to set the buttons for se-
lected stations. On the Wonder-
bar radio, the tuning knob may
also be used to tune in stations
that are too weak to stop the elec-
tronic signal seeking section of
the tuner.
When tuning manually, and par-
ticularly when setting a station on
one of the push buttons, careful
adjustment of the tuning knob is
essential in good radio reception.
On push button selection, if the
program sounds unnatural or dis-
torted, it is probably caused by
improper tuning and can be cor-
rected by adjusting the tuning
knob slightly. Since the low notes
are more affected by improper
tuning than the high ones, it is
desirable to tune the set to a
point where the low notes are
heard best and high notes are
clear and undistorted. This point
may be most readily found by
listening to the background noise
and tuning for the lowest volume
and pitch of this noise. Turning
the control knob back and forth
until the station is almost lost on
either side will enable the oper-
ator to hear the difference in
reception and select the inter-
mediate position giving b e s t
results.
f. AM-FM Radio
This radio is identical to the
Sonomatic or Wonderbar radios
as far as the operation of the on-
off and volume control, tone con-
trol, manual tuning control and
push buttons are concerned. The
AM-FM Selector bar is located
directly above the dial face.
Movement of the bar to the left
exposes the letters "FM" and
switches the radio to FM mode
of operation. Movement of the
bar to the right provides AM
radio operation. An automatic
frequency control circuit is in-
corporated in the radio and acts
to automatically adjust the re-
ceiver to select the strongest of
the incoming signals if the tuner
is adjusted to a point where more
than one incoming signal is being
received. In general the FM mode
of operation will provide greater
reception fidelity and freedom
from static and other atmo-
spheric disturbances. The FM
signal is very susceptible to in-
terference due to tall buildings,