Accuphase T-103

 Digital Display of Tuned Frequency and Correct Time

The Quartz Oscillator and Digital Counter Circuits enable digital 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 add sum radio station frequencies such as 25 kHz or 50 kHz.  A unit of 10 kHz is rounded to the nearest whole number of 100 kHz. For example, when the tuner is receiving a station with a frequency of 92,25 MHz, the digital display shows the rounded figure of 92,3 MHz. Also a tuned frequency of 93,22 MHz  is displayed as 93,2 MHz. Meanwhile, the Center Tuning Meter indicates accurate tuning points, and also shows on the meter 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 5-Gang Tuning Capacitor Completely Rejects Interference

The front-end is virtually the “heart” of any tuner, it selectionate input signal, amplifiers it, and generates and delivers the intermediate frequency of 10,7 MHz to the IF section. Thus, the front-end design technique practically determines the performance of that tuner and its all-important sensitivity and interference rejection capabilities. The T-103 employs a 5-gang variable capacitor and achieves very excellent spurious noise rejection characteristics such as image rejection of 120 dB and RF intermodulation rejection of 75 dB. It also assures a very high sensitivity of 10,3 dBf.

Linear Phase If Circuit Features LC and SAW (Surface Acoustic Wave) Filter Network

The 10,7 MHz IF signal that is generated in the front-end is fed to the IF circuit where it is amplified, its amplitude limited and adjacent station signals eliminated before it is introduced to the discriminator circuit. It 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 Filters.

SAW is short for Surface Acoustic Wave and is a filter device that employs two set of electrodes with comb-like teeth that face each other. One side is excited by a piezo-electric element and the energy is trasduced to the other electrode by surface vibration to achieve electric conversion. It is a new filter device whose frequency add the element. It offers stable, long life performance. This tuner permits a choice of Normal IF bandwidth for low distortion, and Narrow bandwidth for sharp selectivity that effectively eliminates interference of closely adjacent FM stations.

 Low Distortion, Linear Phase FM Discriminator

The FM discriminator derives audio amplitude signals from frequency modulated input signals. Its output amplitude variations must be linear with the frequency variations of the input for low distortion performance. Linearity is checked as follows. A weakly modulated signal is swept and fed to the discriminator input. The output differential gain derived from the frequency variations is recorded and plotted  to measure the flatness of the differential gain characteristics which reveals its distortion ratio.  The circuit employed in the T-103 is a phase conversion type discriminator that derives the audio signal by multiplying the input original signal by the phase-shifted signal which comes through the quadrature network. Because of this newly designed wideband, linear phase shifter, practically no distortion occurs in the T-103 discriminator circuit.

PLL (phase-Locked Loop) Demodulator with Pilot Carrier Cancelling Circuit

A most advanced design PLL demodulator circuit which functions to separate the left-right composite signals for stereophonic reproduction is employed in the T-103. It features a new pilot carrier canceller circuit, which, together with the Linear Phase IF Filter and wideband discriminator, account for the very excellent specifications of 50 dB channel separation at 1 kHz, 45 db at 10 kHz and distortion ratio of less than 0,02% at 1 kHz stereo, which place this tuner in the highest grade class.

Multi-Function Meters

Two meters are available which provide four functions that can be selected by push-button control. Meter functions include Center Tuning with frequency scale for precise tuning, Signal Strength and Modulation indications and Multipath detection.  Input signal strength can be observed on a dBf direct reading scale, modulation on a full scale of 200% (deviation ±150 kHz) and clear mark indication of multipath condition that reveals the optimum FM antenna installation direction.

Other Functions

Other functions include a Noise Filter that helps to eliminate noise during stereo reception of weak signals, a Mode Switch to convert stereo reception to monaural , a Muting Switch to silence interstation noise and Dimmer Switch to dim the illumination of the digital display. Also available are three button switches, Hour, Minute and Check, which function to set the digital clock.

Specifications

Monophonic Section

Sensitivity:  

Usable Sensitivity : 10,3 dBf (1,8 µV)  50 dB 

Quieting Sensitivity : 17,3 dBf (4,0 µV)

Voltage Standing Wave Ratio:  1,5

Signal-to-Noise ratio at 65 dBf (1mV):  77 dB

Distortion at 65 dBf input (with Selectivity switch set to “Normal”) : 

0,03% at 100 Hz; 1,000 Hz; 5,000 Hz; ,

 0,04% at 10,000 Hz

Intermodulation Distortion (antenna input 65 dBf, 100% mod. 14 kHz and 15 khz = 1:1):  will not exceed 0,01%

Frequency response:  +0; -0,5 dB 20 Hz to 15,000 hz

Selectivity (switch set to Normal / Narrow):  

Alternate Channel : 50 dB / 100 dB  

Adjacent Channel : 6 dB /20 dB

Capture Ratio:  1,5 db

RF Intermodulation:  75 dB

Image Response ratio:  120 dB

IF/2 Spurious Response Ratio:  100 dB

AM Suppression Ratio:  80 dB (at input 65 dBf)

Subcarrier Product Ratio:  80 dB

SCA rejection Ratio:  80 dB

Output:  1,5 Volts (at 100% modulation)

Stereo Section

Sensitivity:  

40 dB Quieting Sensitivity : 28,8 dBf (15 µV)   

50 dB Quieting Sensitivity ; 37,3 dBf (40 µV)

Signal-to-Noise Ratio at 65 dBf (1mV):  75 dB

Distortion at 65 dBf Input (with Selectivity switch set to Normal):  

0,03% at 100 Hz; 1,000 Hz   

0,05% at 6,000 Hz   

0,1% at 10,000 hz

Intermodulation Distortion ( antenna input 65 dBf, Standard Stereo mod. 9 kHz and 10 kHz = 1:1):  will not exceed 0,03%

Frequency response:  +0; -0,5 dB 20 Hz to 15,000 Hz

Stereo Separation:  

100 Hz : 50 dB   

1,000 Hz : 50 dB   

10,000 Hz : 45 dB

Stereo and Muting Threshold:  19,2 dBf (5µV)

Genaral Section

Frequency Range:  87,5 – 108 MHz (continuously Variable)

Frequency Display:  

100 kHz Interval   

10 khz Column is rounded to the nearest   

100 kHz Column

Tuning Capacitor:  Frequency Linear 5-gang

Frequency Drift:  ±30 kHz

Output Impedance:  

Audio output Fixed : 200 ohms   

Audio Output Controlled ; 2,5 kohms

FM Antenna Inputs:  300 ohm balanced; 75 ohm unbalanced

Meters:  

Center Tuning meter   

Signal Strength /Multipath/Modulation  

(Combination Meter)

Digital Clock:  Quarts Oscillations System   

Time accuracy ; ±15 seconds/month at 20 °C

Power Requirement:  Voltage selector for 100V, 117V, 220V, 240V  50/60 Hz operation   

Power Consumption:  25 W

Semiconductor Complement:  24 Trs.; 5 FETs; 13 ICs; 25 Diodes

Dimensions (W x H x D):  445 x 128 x 370 mm (17-1/2” x 5-1/16” x 14-9/16”)

Weight:  10 kg (22 lbs) net