TRIO KT-770
¥ 49,800 (released in 1983)
Commentary
FM/AM synthesizer tuner adopting DLLD.
It employs a newly developed wide-band linear detection DLLD (direct linear loop detector).
This is a detection method in which the 10.7 MHz IF signal is directly linearized and detected by a closed-loop detector. In addition, a distortion correction circuit is provided in the closed-loop so that the nonlinear distortion of the VCO and the distortion generated by the IF filter are also reduced to 0.
In FM broadcasting, music signals are FM-modulated and transmitted, and the IF signal at 10.7 MHz is always moved by this modulation.
The DLLD is set so that the VCO moves by the same amount as the change of 10.7 mhz by FM modulation, and the error of the output of the phase comparator is always 0, and only the audio signal is taken out.
In addition, a distortion correction circuit is adopted to suppress the generation of non-linear distortion, and low-distortion wide-band linear detection is realized.
Since the DLLD is a closed-loop detector, the noise generated in the loop is suppressed and the signal-to-noise ratio is improved.
It employs a pulse swallow static control method in which the comparison frequency is set to 25 kHz, which is outside the audible band.
In addition, we have achieved a 98 dB SN ratio by increasing the purity of the local oscillator signal using a local oscillator tunable buffer circuit and a twin varactor diode with low noise and excellent large input characteristics.
Dual gate MOS FETs are used in the RF amplifier and MIX section to improve intermodulation characteristics.
The AM section uses an AM band variable circuit to control the frequency characteristics according to the pre-emphasis amount of each broadcasting station.
.JPG)
Model Rating
| Type | FM/AM synthesizer tuner | ||||
| FM Tuner Section | |||||
| Receiving frequency range | 76 MHz to 90 MHz | ||||
| Antenna impedance | 75 Ω unbalance | ||||
| Sensitivity (75 Ω) | 0.95 μ V (IHF), 10.8 dBf (new IHF) | ||||
| SN ratio 50 dB sensitivity | Mono : 1.8 μ V (IHF), 16.2 dBf (new IHF) Stereo : 24 μ V (IHF), 38.8 dBf (new IHF) |
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| Harmonic distortion factor |
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| SN ratio (100% modulation) | mono:98dB stereo:88dB |
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| Effective selectivity | 60 dB (IHF ± 400 kHz) | ||||
| Stereo separation | 66dB(1kHz) 45 dB (50 Hz to 10 kHz) 40dB(15kHz) |
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| Image interference ratio | 95dB(84MHz) | ||||
| IF interference ratio | 110dB(84MHz) | ||||
| Spurious interference ratio | 100dB(84MHz) | ||||
| AM suppression ratio | 70dB | ||||
| Subcarrier suppression ratio | 70dB | ||||
| <AM Tuner Section> | |||||
| Receiving frequency range | 522 kHz to 1611 kHz | ||||
| Sensitivity | 10 μ V (IHF) 250 μ V/m (loop antenna) |
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| Signal-to-noise ratio | 52 dB (30% modulation 1 mV input) | ||||
| Harmonic distortion factor | WIDE 0.3% to 0.8% Narrow (1000 kHz) | ||||
| Selectivity (IHF) | Narrow 50 dB ~ 30 dB Wide | ||||
| <General> | |||||
| Rated power consumption | 9.5W (Electrical Appliance and Material Control Law) | ||||
| Pwer | 100 VAC, 50/60Hz | ||||
| External dimensions | Width 420x Height 64x Depth 317 mm | ||||
| Weight | 3.4kg | ||||