Audio Database

The

Lo-D FT-420
45,000yen(around the 1976 time)

Description
 
The AM/FM stereo tuner announced as a high cost performance tuner of a stable reception and a quantity faithful play.

The frequency linear-line type 4-unit variable condenser was adopted as front end, and the low noise MOS FET, the conjointly excellent sensitivity, and stonewalling exclusion capacity have been acquired.

It is in the middle cycle amplification stage as if the 4 steps of differentials amplification by IC and three ceramics filters excellent in the phase response are adopted and the outstanding limiter property is given, and the interference-suppression effect has been acquired.
Moreover, IC-ized quadrature detection has realized the modification of a capture ratio while a band realizes a low distortion widely.

Whenever it carries the automatically lockable tuning organization and catches a radio wave at the best receiving point, automatically locking of the received frequency is carried out. For this reason, a stable reception is possible in the best status in distortion or a separation.
Work of the automatic control of IC HA-1137 of a Hitachi has realized this.

The PLL circuitry by IC HA-1156 which the Hitachi developed is carried in the MPX circuitry, and a reception characteristics strong against the influence and the variation per hour of ambient temperature is obtained.

The muting circuit is carried in order to suppress the noise at the time of an inter-office noise or a detune.
This circuitry consists of a reed relay for transmitters which the Hitachi developed, and a control circuit by IC.

The non-aligning type RF amplifying circuit is adopted as AM tuner part, and the AGC property by the outstanding selectivity by a ceramics filter and IC has realized the radio interference and the reception strong against the strength of a radio wave.
Moreover, the spurious characteristics is improved by adoption of the IC-ized balanced type mixer circuit.

The 2m scheme of signal tuning is adopted.

A fixture and two variable lines are prepared in the output-terminal.

FM multipath termination and 4ch out termination are carried.

The wood case of the photograph was sold as an option option.


Rating of a mode
Form FM/AM tuner
<FM tuner part>
Circuit system Dual gate MOS FET using One step of RF
4-unit variable condenser Four-step differential IF amplification
Wide band linear detection machine PLL MPX
Practical speed 1.7microv (IHF)
3.0 microvolts (S/N 50dB, mono)
40 microvolts (S/N 50dB, stereo)
S/N mono:73dB
stereo: 68dB (13.6kHz, LPF using)
THD
mono: 0.2%(100Hz)
0.15%(1kHz)
0.2%(10kHz)
stereo: 0.3%(100Hz)
0.25%(1kHz)
0.5%(10kHz)
Capture ratio 1.0dB
Effective selectivity 80dB
Frequency characteristic 20Hz-15kHz+0.2 -2 dB
Separation 50dB(1kHz)
38dB (50Hz - 10kHz)
Image stonewalling ratio 85dB
IF stonewalling ratio 90dB
Spurious stonewalling ratio 100dB
AM supression ratio 52dB
Carrier leakage supression ratio 65dB
Muting operation level 24dB
Antenna A 300-ohm balance type, a 75-ohm unbalance type
<AM tuner part>
Circuit system One step of aligned type RF, a triple variable condenser
Practical speed 18 microvolts (IHF)
300 microvolt/m (bar antenna)
Selectivity 36dB
S/N 50dB
Image stonewalling ratio 40dB
IF stonewalling ratio 55dB
<Synthesis>
An Output voltage/impedance Fixed: Below 0.65V/6kohm
Variable: Below 0.04V - 1.2V/1kohm
4ch out: Below 0.2V/1kohm
The semiconductor used Transistor: 14 pieces
FET: One piece
IC: Four pieces
Diode: 21 pieces
Supply voltage AC100V, 50Hz/60Hz
AC outlet Power-switch un-interlocking.: One line
Power dissipation
(Electrical Appliance and Material Control Law)
18W
Dimensions Main unit: Width 435x height 144x depth of 394mm
At the time of a wood case using: Width 467x height 179x depth of 400mm
Weight 7.5kg
Option Wood case LA-200 (6,500yen)