Audio Database

ST-450
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