Accuphase T-105
¥ 120,000 (released in October 1980)
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.
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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% |
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| 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) |
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| 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) |
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| 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% |
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| 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 |
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| 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 |
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| Frequency accuracy | ± 0.002% | |||||||||
| Output impedance | Fixed Output : 200 Ω Variable Output : 1.25k Ω (maximum) |
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| Meter | Signal Strength / Multipath / Modulation Switchable | |||||||||
| Semiconductor used | Transistor : 26 FET : 3 IC : 24 Diode : 73 Pieces Opto-coupler : 2 pcs |
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| 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) | |||||||||