Accuphase T 103 Brochure

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T-103

DIGITAL DISPLAY FM STEREO TUNER

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Broadcasting stations are allotted frequencies digitally at regular
intervals over the FM band Therefore, the digital display system is well
suited to show the frequency of a tuned-in FM station. However. there
are probably many listeners who are so used to the conventional slide
rule dial, and station selection by means of pointer position. that they
would prefer to keep tuning in this manner. Because of the growing
tendency to welcome the digital display method, however, and since
digital display techniques are being increasingly adapted recently in
various other fields, Accuphase is making available to PM fans a chOice
between both type tuning aids for its T7103 tuner

There are two methods of tuning for digital display. The first is the
conventional variable capacitor way, and the second IS the electronic
synthesizer method. Each has its merits and demerits.

The variable capacitor way varies the tuning frequency mechanically
as in the past. it is a highly perfected, reliable system which hasa long
history With careful design, it assures a superior performance

The synthesizer system, which is controlled by a quartz oscillator,
tunes electronically, and assures accurate. instantaneous tuning of FM
stations that are programmed beforehand into a memory system.
However, a very high level, frontrend design technique is necessary for
the synthesizer tuner to achieve the same RF performance character
istics of a high grade variable capacnor tuner,

Therefore, it is a mistake to think that ALL synthesizer tuners are
high grade tuners, Rather, it should be understood that the main
difference between the two types of tuners is that only the variable
capacitor system mechanism has been electronized in the synthesizer
tuner. It is, therefore, a fact that as for as tuner performance
capabilities are concerned, there are low grade synthesizer tuners, just
as there are various class variable capacitor type tuners.

The T-l 03 is a hybrid FM Tuner which combines the merits of both
the highly perfected Variable Capacitor Tuning system and the accurate
Digital Frequency Display system, One of its unique features is that its
digital display functions as a clock when the power switch is OFF, and
displays the tuned-in FM frequency when the power switch IS ON.

The combined aggregation of Accuphase Hi-Fi technology was
harnessed to develop the T403 into an ideal FM tuner that possesses
the most outstanding performance capabilities. The success of our
efforts, based on advanced FM tuner design, is attested by the
outstanding specifications that confirm the T4035 Hi-Fi performance
and super selectivity characteristics.

S-gang Front-end

Muting Circuit
Modulation Meter Circuit

PLL Demodulator and
AIM") C'mu" Conslantrvoltage Power

Supply Circuit

IF Circult and Phase
Conversion 'iype
Discriminator

Power Transformer

DIGITAL DISPLAY OF TUNED FREQUENCY AND
CORRECT TIME

The Quaitz Osctllator and Digital Counter cIrCuits enable digltal
display of the tuned frequency in 100 kHz steps and takes the place of
the conventional dial pointer system. Although the tuned frequency is
displayed in 100 kHz steps, frequency is continuously variable to
permit perfect tuning of odd sum radio station frequencies such as 25
kHz or 50 kHz A unit of IO kH/ is rounded to the nearest whole
number of 100 kHz For example, when the tuner is receiving a station
WIIh a frequency of Q2 25 MHz, the digital display shows the rounded
figure of 923 MHZ Also a tuned frequency of 93.22 MHZ is displayed
as 932 MHz, Meanwhile, the Centei Tuning Metei indicates accurate
tuning points, and also shows fin the melei scale, in frequency, how far
the incoming signal may be out of tune

The Digital Display works as a clock to show the correct time when
the Power Switch is OFF It can show the time even when the Power
Switch is ON during radio reception by slightly pressing a button

FRONT-END S-GANG TUNING CAPACITOR
COMPLETELY REJECTS INTERFERENCE

The frontrend is Virtually the "heart of any tuner. lt selecge
input signal, amplifies it, and generates and delivers the intermediate
frequency of f07 MHZ to the IF section Thus, the frontend design
technique practically determines the performance of that tuner and its
allrimportnnl senSitivity and interference reieclion Capabilities The
T403 employs a 5-gang variable capacitor and achieves very excellent
spurious noise rejection characteristics such as image reiection of 120
dB. and RF intermodulation rejection of 75 dB it also assmcs a very
high sensitivity of H13 dBf,

LINEAR PHASE IF CIRCUIT FEATURES LC AND
SAW (Surface Acoustic Wave) FILTER NETWORK

The 107 MHz IF signal that is generated in the front-end is fed to
the IF circuit where it is amplified, its amplitude limited and adiacent
station signals eliminated before it is introduced to the discriminator
circuit, In order to reconcile the high selectivity and low distortion
requirements of the IF section, a SAW filter, which is superior in
selectivity and group delay time characteristics, is combined with LC
Fillers.

SAW is short for Suiface Acoustic Wave and is a filter device that
employs two sets of electrodes with combrlike teeth that face each
other. One side is excited by a oie7o electric element and the energy is
transduced to the other electrode by surface vibration to ac
electric conversion. It is a new filter device whose frequenc
bandwidth can be determined by the shape, resiliency and substance of
the element. It offers stable, long life performance,

Fig. 1 shows the group delay time and amplitude characteristics of
the IF circuitry. The group delay time curve relates to distortion. The
flatter it is the better, and means lower distortion. The chart shows that
group delay time is within 0.06 microseconds within the operating
bandwidth of $100 kHz, which, when converted, means a distortion
ratio of 0,01%. In other words, the distortion ratio caused by the IF
amplifier section of this tuner is less than 0.01% which compares
favorably with the distortion ratio of higher grade audio amplifiers,

This tuner permits a choice
of NORMAL IF bandwidth for
low distortion, and NARROW
bandwidth for sharp selectivity
that effectively eliminates inter
ference of closely adjacent FM
stations.

GROUP DELAY- TIME

TIBA'Noi/vioTH" ,

Fig,1 Group Delay Time and
Amplitude Characteristics of
the IF circuitry.