Lo-D FT-420
¥ 45,000 (released in 1975)
Commentary
An AM/FM stereo tuner announced as a high-cost performance tuner with stable reception and high fidelity reproduction.
The front-end uses a frequency linear four link varicon, combined with a low-noise MOS FET to achieve excellent sensitivity and interference rejection.
In the intermediate frequency amplifier stage, four stage differential amplification by IC and three ceramic filter elements with excellent phase characteristics are adopted, and excellent limiter characteristics and interference removal effect are obtained.
In addition, IC-based quadrature detection realizes a wide bandwidth, low distortion, and an improved capture ratio.
Equipped with an auto-lock tuning mechanism.
With this function, when a radio wave is caught at the best reception point, the reception frequency is kept stable, so that distortion and separation can be received stably in the best condition.
This is achieved by the automatic control function of Hitachi's ICHA 1137.
The MPX circuit is equipped with a PLL circuit based on ICHA 1156 developed by Hitachi, and provides reception characteristics resistant to the influence of ambient temperature and changes over time.
A muting circuit is mounted to suppress inter-station noise and noise during detuning.
This circuit consists of a reed relay for communication equipment developed by Hitachi and a control circuit by IC.
The AM tuner section uses an untuned high-frequency amplifier circuit. The excellent selectivity of the ceramic filter and the AGC characteristic of the IC realizes reception that is resistant to interference and radio wave strength.
In addition, the use of an IC-type balanced mixer circuit improves spurious characteristics.
Uses a 2-meter signal tuning method.
There are two types of output terminals, fixed and variable.
It is equipped with FM multi-pass terminal and 4-channel out terminal.
There was a wood case as an option sold separately.
Model Rating
Type | FM/AM Tuner | ||||
FM Tuner Section | |||||
Circuit system | RF 1st stage using dual gate MOS FET 4-stage variable capacitor 4-stage differential IF amplifier Wideband linear detector PLL MPX |
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Practical sensitivity | 1.7 μ V (IHF) 3.0 μ V (S/N 50 db, mono) 40 μ V (S/N 50 dB, stereo) |
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S/N | mono:73dB Stereo : 68 dB (13.6 kHz with LPF) |
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Harmonic distortion factor |
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Capture ratio | 1.0dB | ||||
Effective selectivity | 80dB | ||||
Frequency characteristic | 20 Hz to 15 kHz + 0.2 -2dB | ||||
Separation | 50dB(1kHz) 38 dB (50 Hz to 10 kHz) |
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Image interference ratio | 85dB | ||||
IF interference ratio | 90dB | ||||
Spurious interference ratio | 100dB | ||||
AM suppression ratio | 52dB | ||||
Carrier leak suppression ratio | 65dB | ||||
Muting action level | 24dB | ||||
Antenna | 300 Ω Balanced Type, 75 Ω Unbalanced Type | ||||
<AM Tuner Section> | |||||
Circuit system | Tuned RF1-stage, 3-series Varicon | ||||
Practical sensitivity | 18 μ V (IHF) 300 μ V/m (bar antenna) |
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Selectivity | 36dB | ||||
S/N | 50dB | ||||
Image interference ratio | 40dB | ||||
IF interference ratio | 55dB | ||||
<General> | |||||
Output Level / Impedance | Fixed : 0.65V/6k Ω or less Variable : 0.04 V ~ 1.2V/1k Ω or Less 4 ch out : 0.2V/1k Ω or less |
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Semiconductor used | Transistor : 14 FET : 1 IC : 4 Diode : 21 |
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Power supply voltage | 100 VAC, 50Hz/60Hz | ||||
AC outlet | Power switch not linked : 1 system | ||||
Rated power consumption (Electrical Appliance and Material Control Law) | 18W | ||||
External dimensions | Body : Width 435x Height 144x Depth 394 mm Wood Case : Width 467x Height 179x Depth 400 mm |
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Weight | 7.5kg | ||||
Sold Separately | Wood Case LA-200 (¥ 6,500) |