Audio Database
T-105
Commentary

A quartz-rock synthesizer FM tuner utilizing microprocessor technology.

The synthesizer type tuning circuit makes a reference frequency with a crystal oscillator, and electronically tunes the front end to the desired signal by a combination of a program divider and a PLL circuit that preset to the required receiving frequency.
Unlike the conventional variable capacitor system, the receiving frequency does not change continuously. Instead, the receiving frequency is accurately locked at 100 kHz intervals and the signal can always be received at the minimum distortion point.

In order to enable manual tuning with the same feeling as the varicon method, it is equipped with a pulse tuning method developed in the T-104. In this method, an optical pulse generator installed inside the rotary knob generates a pulse signal, which controls the synthesizer to change the receiving frequency.
In addition, it is equipped with a memory tuning method in which desired stations are stored in advance and called by one touch operation, and 6 stations can be stored in memory.
In addition, it is equipped with a scanning method that quickly sweeps the received frequency.

The front end section adopts a pure electronic control system using a varactor element combined with a PLL circuit, and the RF intermodulation is greatly improved by the two stage double tuning system and tuning buffer configuration.

The IF circuit employs a bulk wave filter with excellent selectivity and group delay characteristics to achieve both high selectivity and low distortion.
In addition, it is equipped with a セレクティビティー change-over switch that eliminates the interference of adjacent stations, and a dedicated bulk wave filter that achieves both high selectivity and low distortion even at narrow (high selectivity).

The "phase conversion type detector" is used to obtain an audio signal by multiplying the input wave by a signal using a phase shifter (a circuit for shifting the phase) that changes linearly according to the frequency around 90 degrees. This wide-band linear phase shifter achieves excellent detection characteristics.

The stereo demodulation circuit has a PLL demodulator with a built-in circuit to remove the pilot carrier.

In the meter, the input signal level, peak indication modulation degree, and multi-path check are increased by d-system by the changeover switch.
When the input signal level is on the dBf direct reading scale, the modulation factor is 200% in full scale, and the multi-path meter indicator is within the clear mark range, the multi-path meter can receive high-quality radio waves with minimum multi-path.

It is equipped with a noise filter to reduce noise in stereo stations with weak radio waves, a mode switch to switch the stereo broadcast transmission to monaural, a muting switch to remove noise between stations, and a power level control.

There was a natural rosewood cabinet sold separately.

Model Rating
Type Synthesizer FM tuner
MonAural Characteristics
Practical sensitivity 11.2 dBf (2.0 μ V)
S/N 50 dB sensitivity 17.3 dBf (4.0 μ V)
Standing-wave ratio 1.5
Signal-to-noise ratio 80 dB (65 dBf (1 mV) input)
Harmonic distortion factor (65 dBf (1 mV) input ;
± 75 kHz shift, Normal)
100Hz:0.04%
1kHz:0.04%
6kHz:0.08%
10kHz:0.04%
IM Distortion Factor (14 kHz : 15 kHz = 1 : 1) 0.01% (65 dBf (1 mV) input, ± 75 kHz shift)
Frequency characteristic 10 Hz ~ 16 kHz + 0 -0.5 dB
2-signal selectivity (45 dBf at 100 μ V input)
Disturbance wave Normal Narrow
400kHz 60dB 100dB
200kHz 8dB 22dB
Capture ratio 1.5dB
RF intermodulation 80dB
Spurious interference ratio 120dB
Image ratio 120dB
AM suppression ratio (65 dBf (1 mV) input) 80dB
Subcarrier suppression ratio 70dB
SCA interference ratio 80dB
Output voltage (± 75 kHz deviation) 1.0V
Stereo Characteristics
Sensitivity S/N 40 dB : 28.8 dBf (15 μ V)
S/N 50 dB : 37.3 dBf (40 μ V)
S/N (65 dBf (1 mV) input) 75dB
Total harmonic distortion rate (65 dBf (1 mV) input
± 75 kHz shift, Normal)
100Hz:0.04%
1kHz:0.04%
6kHz:0.08%
10kHz:0.08%
IM Distortion Factor (9 kHz : 10 kHz = 1 : 1) 0.03% (65 dBf (1 mV) input, ± 75 kHz shift)
Frequency characteristic 10 Hz ~ 16 kHz + 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
Antenna 75 Ω unbalance
Tuning system Quartz-lock-frock-synthesizer system
Documentation : pulse tuning
Memory : 6 stations
Frequency accuracy ± 0.002%
Output impedance Fixed Output : 200 Ω
Variable Output : 1.25k Ω (maximum)
Meter Signal Strength / Multipath / Modulation Switchable
Semiconductor used Transistor : 26 Nos.
FET : 3 Nos.
IC : 24 Nos.
Diode : 73 Pieces
Opto-coupler : 2 pcs
Pwer 100 VAC, 50Hz/60Hz
Power consumption 25W
External dimensions Width 445x Height 128 (Including Legs) x Depth 370 mm
Weight 8.4kg
Sold Separately Wood Cabinet A-9 (¥ 16,000)