Audio Database
T-104
Commentary

An FM stereo tuner that employs a synthesizer system.

The synthesizer type tuning circuit makes a reference frequency with a crystal oscillator, and adjusts the front end to the desired signal electronically by a combination of a program divider and a PLL circuit to preset the desired receiving frequency. The receiving frequency does not change continuously like the varicon type, but is tuned at 100 kHz intervals.
Since the accuracy of the receiving frequency of the synthesizer system is determined by the accuracy of the crystal oscillator that makes the reference frequency, the T-104 type is tuned to the receiving frequency with an accuracy of 0.002% or less.

For station selection, the system is equipped with a memory tuning function that memorizes the desired station in Araraji and calls it with one touch operation, and a pulse tuning function (PAT. PEND) that can be tuned with the same feeling as conventional manual tuning with rotary knob type.
Memory is available for up to 4 stations. Memory can be called up from 5m away with the attached remote station selector.
Manual pulse tuning consists of an infrared generator and a light receiver sandwiching a circuit screen, and generates a pulse signal by rotating the screen. When the frequency changes, a beep tone is heard, indicating the tuning frequency from both eyes and ears. This beep tone can also be turned off.

A built-in 4-bit micro-computer calculates the reception frequency and gives instructions for writing memory. The memory also contains a nickel-cadmium battery, so it can last for about one year even when the power switch is turned off.
When you turn on the power switch, the battery is automatically charged and can be used semi-permanently.

The front end is a purely electronic control system using a varactor element combined with a PLL circuit.
The input and high-frequency amplification are composed of a two stage double-tuning system, local oscillation tuning, and tuning buffer, and are designed to be resistant to spurious interference.

The IF circuit is a combination of a surface acoustic wave (SAW) filter (surface acoustic wave filter) and an LC filter with excellent selectivity and group delay characteristics to achieve both high selectivity and low distortion rate characteristics.
In the SAW filter, two pairs of comb-shaped electrodes are formed on a piezoelectric body, and piezoelectric excitation is performed on the oscillation side and surface vibration is transmitted to the oscillation electrode for electrical conversion. The frequency and bandwidth can be determined by the elasticity of the material and the shape of the electrode, and stable performance can be maintained for a long period.
Two levels of selection are available : Normal (low distortion rate) and Narrow (high selectivity).

In the detection circuit, a specially designed wide-band ratio detector is adopted to obtain excellent differential gain characteristics, and stereo characteristics are improved.

The stereo demodulation circuit uses a PLL demodulator with a built-in circuit for removing the pilot carrier.
The linear phase IF filter, wide-band detector and PLL demodulation circuit provide excellent separation.

It is equipped with an S-meter for measuring input signal strength and a modulation depth meter for monitoring modulation depth. The word "Tuned" is displayed for the perfect tuning point, and the word "Stereo" is displayed for stereo broadcast transmission reception.
In addition, the S-meter can detect multipath with a push switch.

A remote station selector with a 5-meter cord is included so that you can select memory tuning from a distance.

It is equipped with functions such as a noise filter to reduce noise during stereo reception, a mode switch to force stereo to monaural, a muting switch to remove inter-station noise, and a dimmer switch to reduce illumination according to the brightness of the room and simultaneously turn off the pip tone.

There are two outputs, and the volume of one output can be controlled by the level control on the front panel.

It is stored in the natural wood Rosewood cabinet.

Model Rating
Type Synthesizer FM tuner
MonAural Characteristics
Sensitivity Practical sensitivity : 11.2 dBf (2.0 μ V)
S/N50dB sensitivity : 17.3 dBf (4.0 μ V)
Standing-wave ratio 1.5
S/N (65 dBf (1 mV) input) 77dB
Harmonic distortion factor (65 dBf input
Selectivity switch Normal)
100 Hz : 0.03% or less
1 kHz : 0.03% or less
10 kHz : 0.04% or less
IM Distortion Factor (14 hz : 15 khz = 1 : 1) 0.01% or less (antenna input 65 dBf, 100% modulation)
Frequency characteristic 20 Hz ~ 15000 Hz + 0 -0.5 dB
Two signal selectivity
(45 dBf (100 μ V) input)
Disturbance wave Selectivity Normal Selectivity Narrow
400kHz 50dB 100dB
200kHz 6dB 20dB
Capture ratio 1.5dB
RF intermodulation 75dB
Spurious interference ratio 120dB
Image ratio 120dB
IF/2 spurious response 100dB
AM suppression ratio (65 dBf (1 mV) input) 80dB
Subcarrier suppression ratio 80dB
SCA interference ratio 80dB
Output voltage (100% modulation) 1.5V
Stereo Characteristics
Sensitivity S/N 40 dB sensitivity : 28.8 dBf (15 μ V)
S/N 50 dB sensitivity : 37.3 dBf (40 μ V)
S/N (65 dBf (1 mV) input) 75dB
Harmonic distortion factor (65 dBf (1 mV) input) 100 Hz : 0.03% or less
1 kHz : 0.03% or less
10 kHz : 0.1% or less
IM Distortion Factor (9 kHz : 10 kHz = 1 : 1) 0.03% or less (antenna input 65 dBf, stereo 100% modulation)
Frequency characteristic 20 Hz ~ 15000 Hz + 0 -0.5 dB
Stereo separation factor 100Hz:50dB
1kHz:50dB
10kHz:45dB
Stereo switching input voltage 19.2 dBf (5.0 μ V)
<General>
Receiving frequency 76.1 mhz to 89.9 mhz
Tuning system Quartz lock, frequency, synthesizer, tuning
Frequency accuracy Within ± 0.002%
Output impedance Fixed output terminal : 200 Ω
Variable Output Terminal : 2.5k Ω
Antenna input impedance Balance : 300 Ω
Unbalanced : 75 Ω
Meter 2 pieces
Signal Intensity Meter / Multipath / Modulation Switching Type
Semiconductor used Transistor : 43
FET : 3
IC : 42
Diode : 58 pcs
Opto-coupler : 3 pcs
Pwer 100 VAC, 50/60Hz
Power consumption 25W
External dimensions Width 466x Height 188x Depth 391 mm
Weight 14.1kg