Audio Database

Image of the SX-100S
Commentary

Stereo receiver equipped with servo auto-tuning mechanism.

Both FM and AM are equipped with an auto-tuning mechanism that only requires one touch button press. The servocontrol enables more precise tuning than manual tuning.
The problem with the auto-tuning mechanism was that it was difficult to achieve accurate tuning due to misalignment caused by motor inertia and brush wear.
The SX-100S employs a mechanism that stops at the tuning point by utilizing the fact that the positive and negative DC signals (S-curve) obtained from the discriminator become 0 at the tuning point, instead of using the AFC to compensate for this shift.
The dial indicator moves back and forth slightly to the left and right before it stops. This is because it keeps track of the precise tuning point. If the signal position deviates during reception due to radio waves, it follows and tunes. Also, as long as the dial indicator moves, the muting is automatically activated so that no unpleasant inter-station noise occurs.
This muting is also used as the auto-tuning stop sensitivity level and can be changed further.
Manual tuning can also be performed as usual.

It is equipped with a Local Station switch. When it is turned on, the sensitivity to stop the dial indicator drops by 20 dB.
This allows you to pass through stations with weak radio waves or high noise without stopping, and selectively catch only stations with strong radio waves.
If the FM Stereo Station switch is turned ON, only the stereo broadcast transmission can be selected.

By using the attached remote control unit, both auto-tuning and volume can be operated from a distance.

The FM tuner section combines three FETs and four variable capacitors on the front end, and uses two stages of high frequency amplification. The IF section uses four ICs and two crystal filters with sharp characteristics.

3-stage direct connection type using FET is adopted for the tone control.

There are two Phono inputs, one of which can be used with an MC cartridge by using a separately sold transformer (PP-402).

A preamplifier and a power amplifier can be used separately.

Model Rating
Type Servo control auto-tuning stereo receiver
FM Tuner Section
Practical sensitivity (IHF) 1.7 μ V
Capture Ratio (IHF) 1.0dB
Effective selectivity 65 dB or more
S/N 65dB
Image Interference Ratio (82 MHz) 90 dB or more
IF Interference Ratio (78 MHz) 100 dB or more
Spurious interference ratio (82 MHz) 90 dB or more
AM suppression ratio 50dB
Harmonic distortion factor (100% modulation) Mono : 0.3% or less
Stereo : not more than 0.5%
Stereo separation 40 dB or More (1 kHz)
Residual carrier level 50 dB or more
Antenna 300 ohm balanced
75 Ω Unbalanced Type
Muting Level Controllable
<AM Tuner Section>
Practical sensitivity (IHF) 8 μ V
S/N (30% modulation) 50dB
Image Interference Ratio (1 MHz) 80 dB or more
IF interference ratio 75 dB or more
Antenna Ferrite bar antenna
Power Amplifier Unit
Music Power (IHF) 340W (4 Ω)
208W (8 Ω)
Effective power
20 Hz to 20 kHz output (both channel drive) : 58W + 58W (8 Ω, Distortion Factor 0.5% or Less)
Effective output (both channel drive) : 90W + 90W (4 Ω)
72W + 72W (8 Ω)
Effective output (single-ch drive) : 120W/120W (4 Ω)
84W/84W (8 Ω)
Harmonic distortion factor 0.5% or Less (Effective Output)
Cross modulation distortion factor 0.5% or Less (Effective Output)
Output Bandwidth (IHF) 20 Hz to 30000 Hz
Frequency characteristic 5 Hz to 100000 Hz ± 1 db
Input Sensitivity / Impedance 500mV/120k Ω (at effective output, 1 khz)
Load impedance 4 Ω ~ 16 Ω
Damping factor 40 or More (8 Ω, 1 kHz)
Center channel output voltage 550mV
Preamplifier Section
Output voltage Effective output : 500 mv
Maximum : 3 v
Harmonic distortion factor Not more than 0.1%
Frequency characteristic 15 Hz to 20000 Hz ± 1 dB
Input Sensitivity / Impedance
(1 kHz at effective output)
Phono1 MAG : 2.7mV/50k Ω
Phono1 MC : 110 μ V/30 Ω (Uses MC transformer PP-402)
Phono1 CER : 60mV/100k Ω
Phono2 mm : 2.7mV/50k Ω
AUX1, 2, Tape Mon1, 2 : 200mV/100k Ω
Recorded output Tape Rec1, 2 (pin jack) : 200 mv
DIN connector : 35 mv
Tone control Bass and Treble
Low Filter -8dB(50Hz)
High Filter -10dB(10kHz)
Equalizer RIAA S.T.D
Loudness
(at volume -40dB)
100Hz:+10dB
10kHz:+6dB
Hum and noise (IHF) Phono : 80 dB or more
AUX : 100 dB or more
<General>
Semiconductor used Transistor : 71
FET : 5 pcs
IC : 5
Diode : 53 Pieces
Thermistor : 2
Power supply voltage 100 VAC, 50Hz/60Hz
Rated power consumption 180W
Maximum Power Consumption 360W
External dimensions Width 486x Height 146x Depth 384 mm
Weight 15kg
Attachment Auto-tuning remote control unit
Sold Separately Transformer for MC, PP-402 (¥ 8,700)