Audio Database

KT-8300
Commentary

FM tuner equipped with TRIO's original pulse count detection.

Focusing on the linearity of the detection section, we have adopted a pulse count method in which the entire detection band is straight. Compared with the conventional S-curve detection method, this method is superior in that it can reproduce the broadcast station's music waveform as it is as an output waveform and in principle does not generate any distortion.
In the KT-8300, we have succeeded in integrating the pulse count into an IC, and the circuit design advantage is obtained by condensing the parts that used to constitute discrete elements such as transistors and treating them as one element.

In order to demonstrate the characteristics of the pulse count detection method, a double conversion method is adopted in which the intermediate frequency 10.7 MHz obtained by the first IF is converted to 1.96 MHz.
As a result, the relative frequency shift can be increased, so that the wide-band linear width obtained by pulse count detection can be utilized to improve the SN ratio by increasing the detection efficiency.

For the front end part, a newly developed FM-dedicated frequency linear 5-train varicon is used for the first stage double tuning to minimize IM distortion at the RF stage.
In addition, the use of a dual-gate MOS FET improves the interference rejection capability.

Equipped with IF band 2-stage switching.
A newly developed phase linear-type ceramic filter with four elements, which exhibits a flat group delay characteristic of less than 0.1 μ s (± 150 khz) at the WIDE position, provides high-quality playback sound.
In addition, the NARROW position consists of 8 ceramic filters with sharp characteristics to catch distant stations and weak radio waves.

The MPX section is equipped with a clean subcarrier system and a pilot canceler.
The clean subcarrier system prevents the mixing of audio signal components into the switching signal, so that the pilot canceler can operate correctly without causing beat distortion.

Equipped with a servo lock mechanism, it synchronizes within ± 75 kHz of the station you want to receive. When you release your hand from the knob, the servo lock mechanism pulls in and automatically locks the correct reception frequency.
Since the pulse count method of linear detection is adopted, the part with the best distortion characteristics of the filter can be used and the distortion is minimized.

The low-output impedance design takes advantage of the know-how obtained with the direct drive amplifier system.

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 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:0.04%/0.07%
1kHz:0.04%/0.05%
6kHz:0.05%/0.08%
15kHz:0.05%/0.4%
50 Hz to 10 kHz : 0.06% / 0.15%
narrow 100Hz:0.04%/0.3%
1kHz:0.15%/0.12%
6kHz:0.4%/0.2%
15kHz:0.06%/1.0%
50 Hz to 10 kHz : 0.4% / 0.3%
Signal-to-noise ratio (100% modulation, 1 mv input) mono:84dB
stereo:80dB
Image interference ratio 120dB
Selectivity (IHF) wide:45dB
narrow:60dB(300kHz)
IF interference ratio 110dB
Spurious interference ratio 120dB
AM suppression ratio 65dB
Capture ratio wide:1.0dB
narrow:2.0dB
Subcarrier suppression ratio 72dB
Stereo separation
wide: 55dB(1kHz)
47 dB (50 Hz to 10 kHz)
40dB(15kHz)
narrow: 50dB(1kHz)
40 dB (50 Hz to 10 kHz)
33dB(15kHz)
Frequency characteristic 30 Hz ~ 15 kHz + 0. 3-0. 5 dB
Output Voltage / Impedance
FM (1 kHz, 100% modulation) : 0 V ~ 1.3V/1.5k Ω (variable)
0.75V/2.5k Ω (fixe)
Multipath Output : 0.02V/1k Ω (vertical)
0.35V/10k Ω (horizontal)
Power supply voltage 100 VAC, 50Hz/60Hz
Rated power consumption (Electrical Appliance and Material Control Law) 20W
External dimensions Width 440x Height 153x Depth 402 mm
Weight 7.5kg