Technics ST-3150
¥ 39,800 (around 1974)
Commentary
FM/AM tuner developed based on the same design concept as ST-3500 and ST-3200.
In the front-end section, a wide-band balloon with low conversion loss is adopted for the antenna matching circuit. In the RF-amplification stage, a dual-gate 4-pole MOS-type FET with excellent noise figure, internal feedback capacitance, and mutual conductance is adopted. In the local oscillation circuit, an oscillation coil with a highly stable aluminum core is adopted to achieve high sensitivity, stability, and low noise.
In addition, by separating each block completely, problems such as temperature and humidity are solved.
In the IF stage, three flat group delay flat 2-element ceramic filters are adopted in the selective element system that has a wide flat band of group delay time and minimizes the occurrence of high-order distortion. In addition, in the amplification system, two FM/AM independent high-integration monolithic ICs are adopted, and as the control system, three differential limiters are adopted using two LC filters, a total of six stages are adopted.
The demodulation circuit employs a ratio detector with excellent basic performance and a dispersion transformer with linearity over a wide band to improve overmodulation wave and detuning characteristics.
The MPX circuit uses a PLL method that provides a stable switching signal over a long period of time.
In addition, a double-differential switching system with two main and sub circuits is adopted for the switching system, and the circuit is composed of a high-integration IC to obtain excellent separation characteristics and reliability.
A Cebi Czech type filter with a phase delay time of 5.5 μ S is used as the low-pass filter in the latter part of the MPX section.
A stabilized power supply is used for the power supply to each of the high frequency and low frequency circuits, and a stable voltage can be supplied even if the primary power supply changes by ± 20%.
The AF section consists of a 2-stage PNP-NPN direct-coupled circuit using a low-noise transistor with a stabilized power supply.
A frequency linear type varicon is also used in the AM tuner section.
The MPX High Blend switch is mounted to reduce the noise caused by the weak input signal FM stereo reception.
Equipped with an FM muting switch that cuts out noise between FM stations.
An oscilloscope observation terminal for multi-path detection and FM4ch MPX out terminal are mounted.
Model Rating
| Type | FM/AM Tuner |
| FM Tuner Section | |
| Receiving frequency | 76 MHz to 90 MHz |
| Sensitivity (IHF) | 1.8 μ V |
| Distortion factor | mono:0.2% stereo:0.4% |
| Selectivity | 70dB |
| Capture ratio | 1.0dB |
| Image Interference Ratio (82 MHz) | 55dB |
| IF Interference Ratio (82 MHz) | 80dB |
| Spurious interference ratio (82 MHz) | 85dB |
| AM suppression ratio | 50dB |
| SN ratio (400 Hz, 100% modulation) | 75dB |
| Frequency characteristic | 20 Hz to 15 kHz + 0.2 -1.0 dB |
| Stereo separation | 45dB(1kHz) 35dB(10kHz) |
| Leak Carrier (19 khz, 38 khz) | 60dB |
| Output voltage | 0.7V |
| Antenna terminal | Equilibrium : 300 Ω Unbalanced : 75 Ω |
| <AM Tuner Section> | |
| Receiving frequency | 520 kHz to 1610 kHz |
| Sensitivity | 25 μ V |
| Selectivity | 25dB |
| Image interference ratio (1000 kHz) | 45dB |
| IF Disturbance Ratio (1000 kHz) | 40dB |
| <General> | |
| Pwer | 100 VAC, 50Hz/60Hz |
| Power consumption | 7W |
| External dimensions | Width 386x Height 115x Depth 313 mm |
| Weight | 4.9kg |
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