Kenwood KT-7500 User manual

AM-FM STEREO TUNER
;
INSTRUCTION MANUAL

INTRODUCTION
The purpose of this manual is to acquaint you
with the operating features of your new tuner.
You will notice that in every detail of planning,
engineering, styling, operating convenience, and
adaptability, we have sought to anticipate your
needs and desires.
We suggest that you read this manual carefully.
Knowing how to set up your tuner, to the best
advantage will enhance your listening pleasure right
from the start. You will also become aware of the
ease with which you can adjust your tuner to meet
your special requirements.
PRECAUTIONS CONCERNING INSTALLATION
(a) Avoid locations subject to direct sunlight.
(b) Avoid high or low temperature extremes.
(c) Keep the tuner away from heat radiating
source.
SERIAL NUMBER
Record yourSERIAL NUMBER on the spaces
designated on the warranty card. You will find
the serial number on the back of the unit.
AFTER UNPACKING
After unpacking, we recommend you inspect
and examine the unit for any possible shipping
damage. If your unit is damaged or fails to operate,
notify your dealer immediately. If your unit was
shipped to you directly, notify the shipping com¬
pany without delay. Only the consignee (the per¬
son or company receiving the unit) can file a claim
against the carrier for shipping damage.
We recommend you retain the original carton
and packing materials to prevent any damage should
you transport or ship your unit in the future.
WARNING:
TO PREVENT FIRE OR SHOCK
HAZARD, DO NOT EXPOSE THIS
APPLIANCE TO RAIN OR MOIS¬
TURE.
AC VOLTAGE SELECTION
The KT-7500 operates on 110 ~ 120 volts or
220 ~ 240 volts AC. The AC Voltage Selector
Switch on the rear panel is set to the voltage that
prevails in the area to which the tuner are shipped.
Before operating this unit, make sure that the posi¬
tion of the AC Voltage Selector Switch matches
your line voltage. If not, it must be changed to
the proper setting.
To change, first disconnect the AC line cord.
Then remove the stopper plate and slide the AC
Voltage Selector Switch to the opposite side. Then
reattach the stopper plate to the other side.
Note:
Our warranty does not cover damage caused by excessive
line voltage due to improper setting of the AC Voltage
Selector Switch.
NOTES
1. Units shipped to the U.S.A. and CAN¬
ADA are designed to be operated with
120 volts AC only. Units shipped to
the Scandinavian countries are design¬
ed to be operated with 220 volts AC
only. Therefore the above units are
not equipped with an AC Voltage Selec¬
tor Switch so cl I reference to such a
switch throughout this manual should
be disregarded.
2. Units shipped to all other countries are
equipped with an AC Voltage Selector
Switch on the rear panel that is preset
at the factory to the voltage generally
available in the destination area.
Stopper Plate
ACI10120V 4 ► AC220-240V ACI10-120V< ► A C220-240V
(AC120V~< ► AC220V-) (AC120V-4 ► AC220V-)
1. Remove screw and stopper plate.
2. Switch lever to opposite side.
3. Lock lever by attaching stopper
plate to opposite screw.
( ) is European type.
AC VOLTAGE SELECTOR SWITCH
2 KT-7500( K)

FEATURES .
.3
INTERCONNECTING DIAGRAM.
.4
CONTROLS AND THEIR FUNCTIONS.
.5
CONNECTING INSTRUCTIONS.
.6
CONTENTS
OPERATING INSTRUCTIONS.
POINTS TO BE CHECKED PRIOR TO
.8
SERVICING.
.9
SPECIFICATIONS..
.10
NOTE.
.11
FEATURES
1. Image response characteristic is improved by
the adoption of high-accuracy 5-ganged vari¬
able capacitor.
2. Cross-modulation characteristic is improved
by use of Dual Gate MOS FETs for the RF
amplifier.
3. Inter-modulation characteristic is improved by
use of Dual Gate MOS FET for the mixing
circuit.
4. The IF band selector of WIDE/NARROW is
installed. In the NARROW setting, high selec¬
tivity is assured by use of a 10-element phase
linear ceramic filter.
The circuits of WIDE of the IF band are pro¬
vided with 2-element phase linear ceramic
filter.
Adoption of wide band quadrature discrimi¬
nator has extremely reduced distortion in
stereo reception.
The PLL of MPX is provided with automatic
loop response control to reduce distortion in
stereo receotion.
Since dual power supply system is adopted for
all audio signal lines, dynamic range is very
wide.
Built-in de-emphasizer to match any Dolbyiz-*
ed FM broadcasts.
* Dolby is a trade mark of Dolby Laboratories Inc.
KT-7500( K) 3

INTERCONNECTING DIAGRAM
DIRECTION OF FM OUTDOOR FM INDOOR ANTENNA
STATION ANTENNA
LEFT SPEAKER INTEGRATED AMPLIFIER RIGHT SPEAKER TAPE DECK
4 KT-7500( K)

CONTROLS AND THEIR FUNCTIONS
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® POWER SWITCH
Move up to ON to power the set, down to turn it
OFF. The dial indicator lights when the power is
on.
© OUTPUT LEVEL CONTROL
The signals passing from the OUTPUT (VARIABLE)
terminals can be controlled by the OUTPUT
LEVEL knob. Use the controls in the following
situations:
1) When the KT-7500 is connected to a stereo
amplifier and the output level is too high for
the input terminals.
2) When the tuner output level does not match
that of other units (turntable, tape deck, etc.)
connected to the amplifier.
® TUNING KNOB
Use the tuning knob to select the AM and FM
station desired. Adjust further by tuning for maxi¬
mum deflection of the SIGNAL meter while listen¬
ing to the speaker output.
® IF BAND SELECTOR
Switch positions and functions are as follows:
WIDE — This setting is suitable for normal usage
in an area where no radio interference occurs.
Reception with a low distortion can be expected.
NARROW — This setting is to increase selectivity
against interference from a closely adjacent sta¬
tion.
© FM MUTING SWITCH
This switch silences the interstation noises on the
FM band. However, it may also silence the weak
signals of long distance FM stations or weaker FM
stations in which case it may be necessary to turn
off this switch.
© SELECTOR SWITCH
FM AUTO — For reception of both FM mono¬
phonic and stereo. The tuner will automatically
identify and separate FM stereophonic broadcasts.
When an FM stereo broadcast is tuned in, the
STEREO indication lights up.
MPX FILTER — Unlike FM monophonic recep¬
tion, high frequency noise may sometimes be en¬
countered when receiving FM stereophonic broad¬
casts. The MPX FILTER in this tuner effectively
cuts such disturbances. This switch has nothing
to do with monophonic reception.
FM MONO — For FM monophonic reception.
AM — For AM reception.
® TUNING METER
This meter is used for precise tuning to the center
of the FM channel. Turn the tuning knob until
meter pointer is at the center of the heavy black
area of the meter scale. Center tuning provides
maximum separation and minimum distortion.
® SIGNAL METER
This meter indicates incoming signal strength at
the antenna with correct linearity from the weakest
to the strongest signals.
KT-7500( K) 5

CONNECTING INSTRUCTIONS
FM ANTENNA CONNECTIONS
Since FM broadcast signals travel along a
straight, direct-line path, they become rather weak
behind hills and buildings even in the vicinity of a
broadcasting station. FM signals also become weak
in areas distant from a station even though there
may not be any obstruction to the direct-line path
of the signal. Therefore, a good FM antenna should
be installed in the most effective manner for best
possible FM reception.
FM OUTDOOR ANTENNA
In areas subject to FM multipath interference
such as locations behind hills or in the shadow of
buildings, an outdoor FM antenna should be used.
An outdoor FM antenna is also recommended for
the reception of weak and distant FM stations.
Connections should be made as follows:
1. 300 ohm twin leads should be connected to
the FM 300S7 terminals as shown in fig. right.
2. 75 ohm coaxial cable to the FM 75f2 terminals.
Note:
When a 75 ohm antenna is used for connecting to the
antenna terminals, the 300 ohm terminals should not be
used, and conversely.
T-TYPE ANTENNA
In areas near the FM station, where signals
are strong, stretch the T-type indoor antenna that
is supplied, to its maximum, and connect it to FM
300t7 antenna terminals. This antenna should be
carefully hung in the direction that provides best
reception and clarity. The antenna can then be
taped to a wall or ceiling.
Note:
Consult audio dealer for detailed information on FM
antennas and coaxial cable installations.
Strip the coaxial cable as shown in (A).
Loosen the screws and connect the cable as shown in
Then tighten all screws for a connection like (C).
COAXIAL CABLE (75f2) CONNECTION
6 KT-750CK K)

CONNECTING INSTRUCTIONS
AM ANTENNA SETTING
First tune in an AM station. Then, while
watching the SIGNAL meter, adjust the AM ferrite
bar antenna on the rear panel for the best signal.
Notes:
1. Because the ferrite bar antenna has directive properties,
its direction should be adjusted for best reception while
listening to a station.
2. In fringe areas or in locations surrounded by steel frame
buildings where satisfactory reception cannot be obtain¬
ed with the ferrite bar antenna, an AM outdoor antenna
should be connected to the AM terminal.
OUTPUT JACKS
VARIABLE
These jacks connect to the stereo amplifier's
TUNER or AUX input terminals. The level of
these terminals is controlled by the Output Level
knob on the front panel.
FIXED
These jacks connect to the tape deck Line
Input terminals. The signal level from the output
terminals cannot be controlled from the KT-7500;
this must be done with the tape deck input level
controls.
FM MULTIPATH JACKS
This unit is provided with FM multipath jacks
through which multipath distortion can be detected.
These jacks are connected with an oscilloscope and
the antenna is positioned at the optimum height
and in the best direction by observing the displayed
waveform until distortion can be lowered to a
minimum level, operate as follows:
1. Connect the KT-7500 FM MULTIPATH V
(vertical) and H (horizontal) output terminals
to the respective inputs on the oscilloscope.
2. Tune in an FM broadcast on the KT-7500;
the signal waveform will appear on the screen
of oscilloscope. Then adjust the antenna
height and direction for least multipath recep¬
tion. This will be indicated by a waveform
similar to the one on the left in the figure.
The more multipath signals enter, the more
the waveform will be distorted as shown on
the right in the figure.
Keep the AM ferrite bar antenna
away from the rear panel.
AM ANTENNA SETTING
DET. OUT JACK
The Horizontal output of the FM MULTIPATH can be used for
the purpose of the FM DETECTOR OUT. The FM detector circuit
output is made available here so that this tuner will be ready for
4-channel broadcasting developments in the future. When FM
discrete 4-channel broadcasting becomes a reality, a simple demod¬
ulator connected here will enable you to fully enjoy this coming
development.
FM DE-EMPHASIS SWITCH
Before shipment this switch has been pre-set
to the appropriate position for the delivery area.
Units for the U.S. A. and Canada are set to "75;iisec"
and other units are set to "50jjsec".
Incorrect setting will adversely affect the high
frequency range, so check the position before
operating this unit. If you are in doubt about the
preemphasis used in your area, consult your audio
dealer.
Note:
The "25,usec" position should only be selected when this
equipment is used with an auxiliary Dolby NR adaptor
to receive FM Dolby broadcasts.
KT-7500(K) 7

OPERATING INSTRUCTIONS
FM AND AM RECEPTION
FM RECEPTION
1. Set the SELECTOR* switch to FM AUTO.
2. Set the MUTING switch to ON.
But it affects reception of exceptionally weak'
FM signals, and should therefore be left off.
(For further details, refer to the facing page).
3. Set the IF BAND switch to WIDE.
Note:
However, set this switch to NARROW position to increase
selectivity against interference from a closely adjacent sta¬
tion.
4. Turn the TUNING knob to select a station.
First tune so that the SIGNAL meter needle
swings as far to the right as possible, then
finish the precise tuning by centering the TUN-
ING meter needle. If the STEREO indicator
lamp lights, the broadcast is in stereo; if not,
it is monophonic.
5. If you are using a stereo amplifier, set its
controls for the desired volume level and tone
quality.
6. If continuous high-frequency noise occurs dur¬
ing FM stereo listening, set the SELECTOR
switch to position MPX FILTER.
Note:
It may be impossible to eliminate noise from an FM stereo
broadcast if the signal is extremely weak. In such a case
the relative signal strength can be improved by switching
to FM MONO with the SELECTOR switch. While the
stereo effect will be lost somewhat, a great deal of the
noise can be substantially eliminated in this way.
AM RECEPTION
1. Set the SELECTOR switch to position AM.
2. Turn the tuning knob to select a station. Tune
in so that the SIGNAL meter needle swings
as far to the right as possible.
3. If you are using a stereo amplifier, set its
controls for the desired volume level and tone
quality.
8 KT-7500( K)

POINTS TO BE CHECKED PRIOR TO SERVICING
In initially installing this tuner, improper connections may result
in one of the following indications. Their possible causes and corrective
measures are listed below to facilitate installation. If you cannot find
or correct it, see your audio dealer.
SYMPTOM
PROBABLE CAUSE
CORRECTION
Continuous low frequency buzz. Most
noticeable at night on weak signal stations.
Poor AM reception.
Interference from electrical appliances or
atmospherics.
In ferroconcrete buildings or in areas
remote from the broadcasting station.
Erecting a 10 meter outdoor antenna and
securing good ground conditions should
reduce interference considerably.
Complete elimination is difficult.
An outdoor antenna necessary.
Continuous high frequency whine which
increases at night.
TV interference.
10 kHz beat interference from adjacent
AM station.
Turn TV off. (Neighboring TV set may
also be the cause).
Impossible to eliminate from tuner side.
Use HIGH Filter to cut off high fre¬
quency interference, amplifier side.
Intermittent buzzing or sharp cracking
noise.
Lightning interference.
Interference from fluorescent lamps.
AC plug Connection.
Usually unavoidable in certain areas.
Occurs when lamps are on and cannot
be helped.
Try reversing AC plug connections.
Occurs only on certain stations due to
high voltage power line and cannot be
helped in many areas.
Continuous hiss or buzzing interference
with broadcast.
Becomes louder during stereo.
Incoming signal too weak at ANT terminal.
Erect outdoor FM antenna if only indoor
T-type is used.
A 5 or 7 element antenna is necessary if
you are located at a considerable dis¬
tance from the broadcasting station.
Occasional sharp buzzing or crackling
noise.
Automobile ignition noise. More notice¬
able on weak signals.
Erect outdoor FM antenna as far away
from roads as practicable.
FM Automatic Circuit fails to respond
to stereo broadcast.
Incoming signal is exceptionally weak.
Erect an FM outdoor antenna.
KT-7500(K) 9

SPECIFICATIONS
FM TUNER SECTION (I.H.F.)
Usable Sensitivity
50 dB Quieting Sensitivity
9.8 dBf (1.7 mV)
(Mono)
14.1 dBf
(2.8 mV)
(Stereo)
36.1 dBf
(35 mV)
Signal to Noise Ratio
(Mono)
75 dB
(Stereo)
70 dB
Total Harmonic Distortion
at WIDE
at NARROW
Mono at 100 Hz
0.08%
0.1%
1,000 Hz
0.08%
0.2%
6,000 Hz
0.08%
0.3%
15,000 Hz
0.15%
0.15°>o
Stereo at 100 Hz
0.13%
0.4%
1,000 Hz
0.1%
0.3%
6,000 Hz
0.1%
0.3%
15,000 Hz
0.5%
1.5%
Capture Ratio
1.0 dB
2.0 dB
Alternate Channel Selectivity
30 dB
100 dB (400 kHz)
60 dB (300 kHz)
Stereo Separation
at 1,000 Hz
50 dB
45 dB
50 to 10,000 Hz
43 dB
38 dB
at 15,000 Hz
40 dB
30 dB
Frequency Response
20 Hz to
15,000 Hz +0.2 dB -1.5 dB
Spurious Response Ratio
110 dB
Image Response Ratio
105 dB
IF Response Ratio
110 dB
AM Suppression Ratio
60 dB
Sub Carrier Product Ratio
65 dB
Antenna Impedance
300 ohms balanced & 75 ohms unbalanced
FM Frequency Range
88 MHz to 108 MHz
Output Level
at 400 Hz 100% Mod Fixed
0.75V,
1.2 kohms
Variable
0-1.5V,
1.2 kohms
Multipath Output Vertical
0.2V,
5 kohms
Horizontal
0.3V,
5 kohms
FM DET. Out
0.3V,
5 kohms
AM TUNER SECTION
Usable Sensitivity
14 mV
Signal to Noise Ratio
50 dB
Total Harmonic Distortion
0.5%
Image Rejection
60 dB
Selectivity
35 dB
Output Level Fixed 0.15V
Variable
0-0.3V
GENERAL
Power Consumption
20 watts
Dimensions
W 16-15/16” (430 mm)
H 5-7/8" (149 mm)
D 14-27/32" (377 mm)
Weight (Net)
16.8 lbs. (7.6 kg)
(Gross)
19.4 lbs.
(8.8 kg)
Note: Kenwood follows a policy of continuous advancements in development. For this reason specifications may be changed without notice.
10 KT-7500(K)