Audio Database

ST-S90
Commentary

An FM/AM tuner that employs a synthesizer system.

The front end section is a 4-stage varicap FM electronic tuning type with a local oscillator with a highly stable buffer amplifier. This feature has excellent intermodulation interference characteristics. Even when receiving under a strong electric field, it can withstand input with a margin to prevent input overshooting. It also provides stable reception performance against external radio interference.
In addition, the MOS FET RF amplifier (high-frequency amplifier) amplifies radio waves as they are before receiving them, enabling clear reception.

The detection stage is equipped with an anti-bias filter to improve the adjacent Radio noises rejection capability when receiving an FM stereo broadcast transmission. In this circuit, the detection stage cuts the noise caused by the beat of the harmonics of the pilot signal and the adjacent station separated by 0.1 MHz, so that sound quality is not impaired.

The strong modulation input distortion characteristics have been improved by adopting a ceramic filter with flat group delay characteristics with less distortion in the IF section.
The IF bandwidth is switched between two stages : wide and narrow. When the bandwidth is wide, the IF signal passed through a ceramic filter is sent directly to the detection stage. When the bandwidth is narrow, the signal passes through two stages through a narrow-band ceramic filter, and passes through a broad-band ceramic filter with flat delay characteristics. This realizes low distortion and excellent selectivity.

Both AM and FM use a PLL frequency synthesizer that uses quartz for the local oscillation of the tuner, enabling stable reception.

Static method is adopted for all operation methods, frequency display, each operation display, etc., and stability improvement and noise reduction are realized compared with the conventional dynamic method.

It is equipped with a random preset memory that can store up to 10 AM/FM stations at random.

Equipped with a program timer function, 3 types of functions (Every, Once, and Sleep) and preset station can be specified simultaneously.

High sensitivity and high S / N ratio have been realized by adopting bar antenna and AM electronic tuning IC.

Equipped with a 5-row LED indicator that shows the radio wave condition according to the change of brightness.

Uses a smoked sealing pocket.

Model Rating
Type FM/AM Tuner
FM Tuner Section
Circuit system PLL Frequency Synthesizer Method 4 Series Varicap Front End
Receiving frequency 76.0 mhz to 90.0 mhz
Sensitivity 10.8dBf
Signal-to-noise ratio mono:88dB
stereo:82dB
Distortion factor (wide, 1 kHz) mono:0.03%
stereo:0.04%
Frequency characteristic 20 Hz to 15 kHz ± 0.5 dB
Selectivity wide:50dB(400kHz)
narrow:65dB(300kHz)
Image interference ratio 80dB
IF interference ratio 90dB
AM suppression ratio 65dB
Separability 50dB(1kHz)
40 dB (100 Hz to 10 kHz)
Rated output 0 ~ 800mV/2.2k Ω
Capture ratio 1.0dB
<AM Tuner Section>
Receiving frequency 522 kHz to 1710 kHz
Sensitivity 230 μ V (bar antenna)
Signal-to-noise ratio 58dB
Distortion factor 0.5%
IF interference ratio 68dB
Image interference ratio 59dB
<General>
Pwer AC100V 50Hz/60Hz
Power consumption 15W
External dimensions Width 420x Height 84x Depth 414 mm
Weight 4.4kg