Aurex ST-450
¥ 47,000 (around 1978)
Commentary
A digital synthesizer tuner equipped with a 2-band digital system of AM/FM and a presetting mechanism for 12 stations including AM/FM.
Manual tuning in which channels are selected by the UP/DOWN operation of the TUNING switch. By operating the UP/DOWN buttons, FM automatically scans and stops at the frequency of the broadcasting station. Automatic tuning in which AM can be selected in 9 kHz steps. Preset tuning of 6 AM / 6 FM stations that can be recalled at any time by pressing the memory button after automatic or manual selection.
These three tuning methods are available. In AUTO, muting works, stereo broadcast transmission is received in stereo, and monaural broadcasts are received in monaural. In MANUAL, muting is turned off so that both stereo and monaural broadcasts are received in monaural. You can also receive stereo signals by switching to AUTO after manual tuning.
The reception frequency is digitally displayed with a 7-segment LED.
The signal for adjusting the recording level of the deck can be taken out by the air check calibration switch installed on the front panel.
When the switch is turned ON, reception stops temporarily and a 1 kHz signal of the same level as that of 50% FM modulation can be obtained. By adjusting the signal according to this, clipping due to over-input or SN ratio degradation due to under-input can be prevented.
The newly developed high-integration LSI simplifies the tuning section and control section, which previously required many ICs, with two LSIs.
LSI TC-9123P is adopted for the tuning part.
This PLL LSI integrates 1,700 elements in a 3.3 mm sq. chip, and realizes a synthesizer up to high frequencies by using a superspeed prescalar in addition to the program frequency divider of the conventional synthesizer system.
LSI TC uses LSI TC-9124P.
This LSI has a higher integration than the TC-9123P, and 5,400 elements are integrated in a chip of 4.9 mm square. It is equipped with many functions such as AM/FM band designation, memory function / memory call, auto / manual tuning, frequency display signal output, etc.
By incorporating a local oscillator circuit into a part of the PLL loop, we have adopted a PLL system that creates and keeps an accurate oscillation frequency.
Quartz is used to guarantee the accuracy of oscillation frequency.
Model Rating
Type | FM/AM Tuner |
Circuit system | AM/FM : PLL digital frequency synthesizer system |
Selecting station | Auto Tuning (FM) Preset tuning (direct for 6 FM stations and 4 AM stations) |
FM Tuner Section | |
Receiving frequency | 76.0 mhz to 90.0 mhz |
Practical sensitivity | 10.8 dBf (0.9 μ V, 75 Ω) |
Frequency characteristic | 20 Hz to 15 kHz ± 1 dB |
Effective selectivity | 60 dB (± 400 kHz) |
Distortion factor | mono:0.1% stereo:0.2% |
Signal-to-noise ratio | mono:72dB stereo:68dB |
Capture ratio | 1.5dB |
Stereo separation factor | 40dB(1kHz) |
Rated output | 600 mv (400 Hz, 100%) |
<AM Tuner Section> | |
Receiving frequency | 531 kHz to 1602 kHz |
Practical sensitivity | 300 μ V/m |
Effective selectivity | 30dB |
Image interference ratio | 35dB |
Signal-to-noise ratio | 50dB |
<General> | |
Pwer | AC100V 50Hz/60Hz |
Power consumption | 6W |
External dimensions | Width 420x Height 57x Depth 292 mm |
Weight | 3.2kg |