Audio Database

The

Lo-D FT-620
55,000yen(around the 1976 time)

Description
 
The AM/FM stereo tuner in which the sensor automatically locking tuning organization was carried.

A frequency linear-line type 4-unit variable condenser and the dual gate MOS FET of a low noise are adopted as front end, and high sensitivity-ization is attained.

High selectivity has been obtained, while adopting the 4 steps of differentials amplification by IC, and three ceramics filters excellent in the phase response as a middle cycle amplifying circuit and giving the limiter property of a high level.
Furthermore, wide band quadrature detection was adopted as the detection stage, and the capture ratio is improved while realizing a low distortion.

In order to hold the best receiving point correctly, the sensor automatically locking tuning organization is carried.
Once this automatically lockable organization catches a radio wave at the best receiving point and receives a radio wave, it can always hold that received frequency. Furthermore, many properties, such as distortion and a separation, are stably received and held in the best status.
It is based on work of the automatic control by IC, a dial pointer shines red throughout this automatically locking, and this tells the best point reception and a stable hold without finger.
If a hand touches a tuning thumb at the time of tuning, an automatically lockable organization will separate, and the manual tuning by a center tuning meter can be performed.

The PLL (phase locked loop) circuitry by IC HA-1156 is adopted as a MPX circuitry.

The muting circuit by the reed relay and IC is carried.

AM tuner part is attaining low noise-ization.

The MPX noise filter, FM multipath termination, and the band indicator are carried.

The level adjustment organization is carried in each AM/FM.

4ch out termination is 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
Super-wide band linear detection machine PLL MPX
Practical speed 1.6microv (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 or more
IF stonewalling ratio 90dB or more
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 40dB
S/N 50dB
Image stonewalling ratio 65dB or more
IF stonewalling ratio 85dB or more
<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: 24 pieces
FET: One piece
IC: Four pieces
Diode: 25 pieces
Supply voltage AC100V, 50Hz/60Hz
AC outlet Power-switch un-interlocking.: One line
Power dissipation
(Electrical Appliance and Material Control Law)
19W
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 7.8kg
Option Wood case LA-200 (6,500yen)