TRIO KT-9900

Commentary

An FM stereo tuner that eliminates the two demodulation processes, FM demodulation and stereo demodulation, which cause sound quality degradation.

Sample-and-hold MPX is used to improve stereo demodulation.
The Sample-and-Hold MPX of the KT 9900 uses a pulse waveform instead of a square wave as a switching waveform, and only the 38 khz peak is accurately sampled, so that the separation of the multi-unit can be almost infinite.
Since sampling alone lowers the average level, the sampling signal is held until the next sampling signal arrives and the average level is raised to improve the SN ratio.
In this method, since only the peak is sampled and held, the amplitude of the 38 kHz component changes little when modulation is applied, and dynamic carrier leakage due to changes in the modulation level of speech hardly occurs. Together with the pilot canceler, the frequency characteristics of the low-pass filter in the final stage are improved.

Equipped with newly developed distortion ディテクティッ droop.
Unlike conventional synthesizers and AFCs, this mechanism not only locks the front-end frequency, but also locks the frequency at the minimum point of total distortion after it passes through an IF filter and is detected. Since the front-end and low-pass filters are comprehensively managed, even if the local oscillation frequency shifts or the IF filter drifts due to changes in temperature or humidity, this mechanism always follows and maintains the minimum point of distortion.
If you turn the tuning knob and release your hand when the desired radio wave is detected, it will be pulled to the minimum distortion point and lock the desired FM station.

The front end is composed of a double-double-triple tune with a 9-series variable capacitor with a wide air gap and a frequency linear high-precision variable capacitor. In addition to the double-tune configuration of the first stage in particular, a DD-MOS type FET with a large power gain and a wide dynamic range is adopted. By using the region with the best linearity, the amplitude characteristics of the RF section are significantly improved to approximately 25 dB even at a distance of 5 MHz.

By combining a balanced mixer with four Schottky barrier diodes with a high-precision coil and a newly developed transformer, we have achieved a low distortion factor.
In addition, the amplifier receiving this mixer uses a differential amplifier and constant current load circuit with a wide dynamic range and excellent distortion characteristics, and the distortion level at IF and OUT is improved by 10 dB as input conversion.

A newly developed unidirectional SAF (surface acoustic wave filter) is adopted in the IF stage, and it has succeeded in suppressing the ripple caused by the wave in the opposite direction generated by the conventional SAF.
The KT 9900 achieves excellent reception characteristics by configuring 3-stage switching of the IF band using newly developed SAF and CF (ceramic filter) with flat group delay characteristics.

Equipped with auto Chinese arrowhead control, L / R blend amount is varied according to input signal level, and SN day is automatically controlled so that it does not become 50 dB or less.
This circuit is normally in the AUTO position so that all input signals can be received in the optimum condition.

Model Rating

Type	FM tuner
Receiving frequency	76 MHz to 90 MHz
Antenna impedance	300 Ω equilibrium 75 Ω unbalance
Sensitivity	75 Ω : 10.8 dBf (new IHF) / 0.95 μ V (IHF) 300 Ω : 10.8 dBf (new IHF)
SN ratio 50 dB sensitivity (75 Ω)	Mono : 15.8 dBf (new IHF) / 1.7 μ V (IHF) Stereo : 37.2 dBf (new IHF) / 20 μ V (IHF)
Distortion factor	mono stereo wide 100Hz: 1kHz: 6kHz: 15kHz: 50 Hz to 10 kHz : 0.02% 0.03% 0.05% 0.03% 0.05% 0.06% 0.04% 0.07% 0.25% 0.09% normal 100Hz: 1kHz: 6kHz: 15kHz: 50 Hz to 10 kHz : 0.02% 0.06% 0.15% 0.03% 0.15% 0.1% 0.09% 0.15% 0.4% 0.2% narrow 100Hz: 1kHz: 6kHz: 15kHz: 50 Hz to 10 kHz : 0.02% 0.15% 0.4% 0.03% 0.4% 0.2% 0.12% 0.2% 0.9% 0.25%
Signal-to-noise ratio (100% modulation, 1 mv input)	mono:90dB stereo:84dB
Image interference ratio	125dB
Selectivity (IHF)	wide:35dB normal:60dB narrow:60dB(300kHz)
IF interference ratio	125dB
Spurious interference ratio	125dB
AM suppression ratio	70dB
Capture ratio	wide:0.8dB normal:1.0dB narrow:1.5dB
Subcarrier suppression ratio	73dB
Stereo separation	wide 1kHz: 50 Hz to 10 kHz : 15kHz: 60dB 50dB 40dB normal 1kHz: 50 Hz to 10 kHz : 15kHz: 55dB 45dB 38dB narrow 1kHz: 50 Hz to 10 kHz : 15kHz: 50dB 40dB 33dB
Frequency characteristic	10 hz to 16 khz + 0. 2-0. 5 db
Output Voltage / Impedance	FM (1 kHz, 100% modulation) Variable : Fixed: 0 V ~ 1.5V/60 Ω 0.75V/60 Ω Multipath output Vertical : Horizontal: 0.01V/10k Ω 0.5V/3k Ω
Power outlet	Power switch not linked : 1 system, 300W
Power supply voltage	100 VAC, 50Hz/60Hz
Rated power consumption (Electrical Appliance and Material Control Law)	50W
External dimensions	Width 460x Height 161x Depth 463 mm
Weight	15kg