Harman Kardon 75+ - Tuning and Signal Management; Tuning and Broadcast Selection; Dial Scale and Equalization; Troubleshooting Hum and Noise

TUNING
The tuning knob, located on the right side of the receiver is used to select
the desired station when your FUNCTION switch is in the FM, STEREO FM, or
AM position.
SELECTING MONOPHONIC OR FM STEREO BROADCAST
Under normal use for all FM broadcasts the function selector switch should
be placed in the STEREO FM position.
Your receiver is equipped with a stereo sensing circuit which will auto-
matically determine whether your unit is receiving monophonic or stereophonic
broadcasts, and then automatically adjust the mode of operation.
If the station is transmitting stereo, your receiver will automatically switch
on the multiplex section and you will hear the broadcast in full stereo. Should
the station conclude broadcasting in stereo, your receiver will automatically
switch back to monophonic reception.
Should
you
receive
a
weak
stereo
signal
whose
quality
has
been
degraded
by
noise
or
poor
signal
conditions,
and
you
wish
to
listen
to
this
stereo
broad-
cast
monophonically,
place
the
function
selector
switch
in
the
FM
position.
STEREO INDICATOR
A stereo indicator is located adjacent to the tuning meter and operates
in conjunction with the STEREO FM position of the Function switch. The indica-
tor visually shows the reproduction of FM stereo through your receiver.
To tune for FM stereo proceed as follows:
1. Place the function selector switch in the STEREO FM position.
2. Tune to the station of your choice using your tuning meter for precise and
accurate tuning. Your stereo indicator will now show if you are tuned to a
stereo program. If the indicator is off, the program you are listening to is
being broadcast monophonically.
TUNING METER
Your Receiver incorporates a D'Arsonval movement tuning meter for precise
and accurate tuning.
The FM balance meter is designed to operate on a null or ‘‘zero’’ center
principle. Therefore, the meter pointer should always be at the dead center
position of your meter dial for optimum listening performance. To accomplish
this, rotate your tuning knob slowly, in one direction towards the station of your
choice. As you tune through the station you will notice the pointer swinging from
the left or right past the zero center. THE CORRECT POINT for minimum distor-
tion and optimum FM reception is when the pointer is resting at the ‘‘zero”
center position.
When used in the AM position, simply tune for maximum indication.
DIAL SCALE
The dial scale on your receiver is marked with three scales, namely, an
FM frequency scale (88-108 MHz), a logging scale (0-100), and an AM frequency
scale.
Since most FM stations operate at frequencies which are not whole num-
bers (such as 96 MHz as compared to 96.3 MHz), ideally, each megahertz division
on the frequency scale should be divided into 10 parts to enable the user to
Pinpoint the location of the station. This would require a dial scale which would
be longer than the front panel.
The logging scale which is divided into 100 equal parts provides a means
of finding your favorite station, once you have noted its position on the logging’
scale. For example, in New York City, WQXR operates at 96.3 MHz. After
locating this station through the use of the frequency scale (between 96 and 98
MHz), you find that the pointer may fall on 4.2 on the logging scale. Make a
note of this setting, For future tuning to WQXR simply set the pointer to 4.2 on
the logging scale.
EQUALIZATION
In order to achieve good reproduction of the wide range of frequencies
in music and to make necessary adjustment for the limitations of the recording
technique, record manufacturers have found it necessary to modify the actual
frequency response of the music while it is being recorded. Thus, to avoid
overcutting and consequent distortion, a measured and deliberate reduction is
effected in low frequency response by selecting a ‘turnover frequency” and
recording attenuated response below that point. To assure optimum signal to
noise at the high frequency end when the record is played at home, the highs
are deliberately exaggerated during the recording process. A measured and
deliberate boost is affected above a certain frequency. This combination of
deliberate exaggeration at the low and high ends of the frequency spectrum
can be expressed in a recording curve. When the record is played a mirror
image of that curve should be available so that the ideal ‘‘flat’’ response may
be achieved.
The PHONO position of the function switch automatically introduces the
proper equalization.
HUM AND NOISE
In any high fidelity installation, hum may be caused by the interconnection
of a record player, tuner and amplifier, as a result of the cables and different
grounds, If hum is experienced with your receiver, disconnect everything but
the speakers from the receiver. If hum persists, reverse the AC line cord. Plug
in the record player and if hum appears, reverse the record player power plug
and connect a single lead from the record player chassis to the ground post
on the rear of the receiver chassis. Connect your other devices in this manner.
CAUTION: Hum may also be induced by defective connecting cables or by
running these cables too close to a strong AC field.