TRIO KT-8100

Commentary

FM/AM tuner using pulse count method.

The detection section employs a pulse count method in which the entire detection band is straight.
Compared with the conventional S-curve detection method, this method can reproduce the broadcast station's music waveform as it is as an output waveform, so that in principle no distortion occurs.
In addition, the KT-8100 has been successfully integrated into an IC, and by treating the detection system itself as a single stable element, we have obtained advantages in circuit design.

In order to demonstrate the characteristics of the pulse count detection method, a double conversion method is adopted.
In this method, the intermediate frequency of 10.7 MHz obtained by the first IF is further converted to 1.96 MHz. By increasing the relative frequency shift, the wide-band linearity obtained by pulse count detection can be utilized, and by increasing the detection efficiency, the S / N ratio is greatly improved.

It is equipped with IF band 2-stage switching in order to correspond to various examination conditions.
The WIDE section is composed of two stages of phase linear two element filter with excellent group delay characteristics. Combined with the adoption of pulse count IC, excellent distortion factor characteristics are obtained. Also, high SN ratio is obtained by double conversion system.
The NARROW position consists of three stages of two narrow-band ceramic filter elements, and exhibits high selectivity characteristics and excellent interference rejection capability.

The front-end uses a dual-gate MOS type FET and a four series frequency number line varicon, providing high sensitivity and large input characteristics, as well as excellent interference rejection capability.

In the MPX part, a low distortion factor is achieved by examining the tracking filter action when detecting the pilot signal of the PLL, and stable separation over a wide band is obtained by adopting a PLL that is resistant to temperature and humidity and supplies a stable switching signal over a long period.

The low-pass filter is an L/R-independent 5-element filter that achieves both excellent frequency characteristics and carrier leakage. The pre-amplifier uses an NFB amplifier built into the IC to maintain a low distortion factor even during overmodulation.

The FM muting circuit employs an FET switch control method at the high signal level of the audio output to sharply eliminate inter-station noise. A plus / minus time difference circuit operates when the power is turned on / off to prevent pop noise and shock noise.

The IF stage of the AM tuner section employs a high-selectivity ceramic filter combining two 3-terminal ceramic filter elements and a coil, and a new IC. The RF stage also incorporates a spurious trap circuit that cuts out the outside of the reception band to eliminate beat interference from short wave bands.
In addition, it has a built-in 9 kHz filter to match the new channel plan, eliminating beats caused by interference between AM stations.

Both AM and FM use linear frequency type varicon. It is a Longs scale with effective length of 270 mm, and smooth tuning is made possible by the adoption of differential pulleys and large 60 φ flywheels.

Model Rating

Type	FM/AM Tuner
FM Tuner Section
Receiving frequency	76 MHz to 90 MHz
Antenna impedance	300 Ω equilibrium 75 Ω unbalance
Sensitivity	75 Ω : 10.3 dBf (new IHF) / 0.9 μ V (IHF) 300 Ω : 10.3 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 : 0.05% 0.05% 0.065% 0.09% 0.065% 0.1% 0.06% 0.1% 0.4% 0.15% narrow 100Hz: 1kHz: 6kHz: 15kHz: 50 Hz to 10 kHz : 0.06% 0.17% 0.4% 0.09% 0.4% 0.5% 0.25% 0.25% 1.5% 0.7%
Signal-to-noise ratio (100% modulation, 1 mv input)	mono:81dB stereo:78dB
Image interference ratio	90dB
Selectivity (IHF)	wide:45dB narrow:54dB(300kHz)
IF interference ratio	100dB
Spurious interference ratio	105dB
AM suppression ratio	65dB
Capture ratio	wide:1.0dB narrow:2.0dB
Subcarrier suppression ratio	65dB
Stereo separation	wide 1kHz: 50 Hz to 10 kHz : 15kHz: 55dB 40dB 38dB narrow 1kHz: 50 Hz to 10 kHz : 15kHz: 48dB 35dB 30dB
Frequency characteristic	30 Hz to 15 kHz + 0.2 -1.5 dB
<AM Tuner Section>
Receiving frequency range	520 kHz to 1650 kHz
Sensitivity	13 μ V (IHF) 250 μ V/m (bar antenna)
Distortion factor	0.4%
Signal-to-noise ratio (30% modulation, 1 mv input)	50dB
Image interference ratio	60dB
Selectivity (IHF)	38dB
<Others>
Output Voltage / Impedance	0.75V/1.8k Ω
Power supply voltage	100 VAC, 50Hz/60Hz
Rated power consumption (Electrical Appliance and Material Control Law)	12W
External dimensions	Width 440x Height 153 (146) x Depth 402 mm
Weight	7.2kg