Audio Database

The

DENON TU-750
42,800yen(around the 1981 time)

Description
 
The synthesizer tuner which aimed at improvement in operativity taking advantage of the merit of a digital tuner.

It corresponded to frequency arrangement of each broadcasting station of FM/AM, and the synthesizer system with which FM aligns with 100kHz and AM sides every 9kHz is adopted.
This system carries out phase comparison of the standard frequency obtained from a crystal oscillator, and the local oscillation frequency, since it forms PLL which controls a varactor diode, does not have a drift of local frequency, either and is enabling good and stabilized reception.

Functions, such as preset tuning (one-touch tuning), auto tuning, and manual tuning, are also carried.
In preset tuning, if the seven FM/AM each preset function is carried and a favorite broadcasting station is tuned in, a memory will be made by pushing a memory button and a preset button (1-7).
In auto tuning, if auto is specified with a scanning button and a one push of a rise or down of a tuning key is carried out, an electric wave is automatically looked for to the one where frequency is higher, or the lower one, and it stops with an exact aligning point. Furthermore, if the tuning key is pressed again, the following aligning point will be looked for.
Manual tuning can be tuned in by specifying a manual with a scanning button and operating each tuning key of a rise and a down. The received frequency can catch the electric wave which it is displayed with a digital counter and cannot be caught by auto tuning.

The IC memory circuit is carried and all the states before turning OFF a power source are memorized.
The backup power supply which will operate for five years or more is used for a memory circuit.

The front end uses for and constitutes the four-step varactor diode and MOS FET equivalent to an analog-type 4-unit variable condenser type.
Moreover, the linear phase ceramic filter which is compatible in a low distortion and the degree of high selection is used for an intermediate frequency magnification stage (IF stage), and it has improved the distortion in all the zones.
Quadrature detection IC which has linear detection capability in a detection circuit over a broadband is adopted, and PLL-MPX-IC is adopted as the MPX section.

In order to transmit without degrading a music signal, the line amplifier of direct-current composition from which the coupling capacitor was removed is adopted.

In order to raise the sensitivity of AM, and S/N, the sound quality which does not have a 9kHz beat obstacle by IF stage which made attenuation outside a zone sharp, and which combined the coil with two steps of 3 terminal type high selection degree ceramics filters has been obtained.
Furthermore, the small low impedance loop type antenna strong against the noise in space is adopted. This antenna has a back panel and free attachment and detachment, and they can install it in the good place of a receiving state in about 1m.

The secondary power transformer winding wire of the power-source part made it become independent the object for digital display pipes, the object for synthesizer parts, and for general circuits, and has realized operational stability of each section.

A dimmer switch can adjust the brightness of a digital display to two steps.

The oscillator for a recording level check convenient for an air check is built in.
An Output voltage corresponds on the frequency of 440Hz at the time of FM50% abnormal conditions.

The electronic change is adopted as each function of FM/AM/Rec.Cal.

power-source on-off -- the muting circuit which removes the following noise and the noise between offices is built in.


Rating of a mode
Form AM/FM tuner
<FM tuner part>
Received frequency 76.1MHz - 89.9MHz
Antenna terminal 75ohm, 300ohm (terminal type)
Practical speed 0.9 microvolt / 10.2dBf
S/N50dB sensitivity stereo: 15.8 microvolts / 35.2dBf
mono: 1.5 microvolts / 14.2dBf
(microvolt is 75-ohm o'clock and 0dBf is 10-15W (new IHF standard).)
Image disturbance ratio 80dB
IF disturbance ratio 90dB(76MHz)
Spurious response 90dB(83MHz)
AM oppression ratio (IHF) 55dB
The degree of effective selection 60dB (±400kHz)
Capture ratio 1.0dB
Frequency response 20Hz-15kHz+0.2 -1 dB
Signal to noise ratio stereo:75dB
mono:80dB
THD (1kHz) stereo: 0.08% (at the time of 90% abnormal conditions)
mono: 0.06% (at the time of 100% abnormal conditions)
Stereo separation 55dB(1kHz)
Muting operation level 22dB
Output voltage 0.6V (at the time of 100% abnormal conditions)
<AM tuner part>
Received frequency 522-1611kHz
Antenna A terminal type, loop form antenna attachment
Practical speed (S/N20dB) 18 microvolts
The degree of selection 50dB (±9kHz)
Signal to noise ratio 55dB
THD 0.6%(1kHz)
Output voltage 0.2V (at the time of 30% abnormal conditions)
<Level check signal>
Frequency 440Hz sine wave
Output voltage 0.3V (at the time of 50% abnormal conditions)
<Synthesis>
Power source AC100V, 50Hz/60Hz
Power consumption 6W
Dimensions (a knob, a base, a terminal included) Width 434x height 66x depth of 266mm
Weight 3.1kg