Audio Database

The

Pioneer TX-810
53,000yen(around the 1973 time)

Description
 
The FM/AM tuner which adopted high-integrated IC equivalent to 203 elements, and the phase linear ceramics filter.

In the front end part, the dual gate MOS FET of a low noise is selected carefully, it is adopted as RF stage and the mixer stage, and practical speed is raised.
Furthermore, radio-interference exclusion capacity is raised by the tuning circuit which uses a 4-unit variable condenser.

The buffer circuitry is established in the local oscillator circuit, also when the office where field strength is strong adjoins, it drew by work of a buffer circuitry and the event with an unstable event etc. is prevented.

Original IC for IF which summarized 203 elements to one with the technology of Pioneer is adopted as the IF section.
Furthermore, it excelled in the linearity over the wide band in the detection circuitry, and little quadrature detection is adopted.
Moreover, the phase response in a passband was thought as important and the phase linear ceramics filter is adopted.

The SCA beat interference and the separation were coped with, high-integrated IC is adopted as a MPX circuitry, and the property is improved by adoption of a double balance type differential demodulation scheme.
Moreover, since the low pass filter which cuts a harmful remains carrier (19kHz and 38kHz) is used, the carrier leakage has also decreased.

The ceramics filter is adopted as IF stage of AM tuner part, a sharp slope property is acquired with moderate bandwidth, and the modification of selectivity and a tone quality is measured.
Moreover, the stability at the time of a strong input is raised by adoption of high-integrated IC developed only for AM.
Furthermore, there is no distortion in a local oscillation wave at adoption of a balance type mixer, and the spurious characteristics is also good.

The AM section is also improving the image stonewalling ratio and IF stonewalling ratio by adoption of the 1 step of aligned type RF amplification which uses a triple variable condenser.

The muting circuit is carried, the transitional pop noise at the time of tuning stops by the double action effect by the combination of semiconductor switching and a reed relay, and the unpleasant shocking noise at the time of a syntony is stopped.

The signal meter of a new method is adopted.
An input signal is taken from each limiter stage, and an input signal until it results in the Dainyuu power from a small input is correctly followed for the scheme which adds a signal with a sufficient linearity to meter in a loose curve through detection and direct-current amplifier with a level detector.

The amplifier for headphone has adopted the OTL amplifier of a Darlington connection, and a loudness level of sound can be controlled in the front panel.

It is used, when the multipath termination is carried and the fewest orientation of an antenna of the cross interferencee by the multipath reflection of an elastic wave is chosen.
By connecting stereo display-device subset-dependency-100 and an oscilloscope, the best point of the orientation of an antenna can be searched for easily.

The MPX noise filter which omits a noise at the time of a reception of FM stereophonic broadcasting is carried.

The output-terminal carries a fixture and two variable lines, and FM and AM can adjust independently the Output voltage of a variable output-terminal.

Rear
Internal
Internal
A

Rating of a mode
Form AM/FM stereo tuner
<FM tuner part>
Circuit system One step of MOS FET RF, a 6 steps of 4-unit variable condenser limiter
Quadrature detection
Practical speed (IHF) 1.8 microvolts
Capture ratio (IHF) 1dB
Effective selectivity (IHF) 80dB
S/N ratio 70dB
Image stonewalling ratio (82MHz) 90dB or more
IF stonewalling ratio (82MHz) 100dB or more
Spurious stonewalling ratio 100dB or more
AM supression ratio 55dB
THD mono: 0.2% or less
stereo: 0.4% or less
Frequency characteristic (stereo) 20Hz-15kHz+0.2 -2.0 dB
50Hz-10kHz+0.2 -0.5 dB
Stereo separation 1kHz : 40dB or more
50Hz-10kHz : 30dB or more
Carrier leakage supression ratio 65dB
Antenna 300-ohm balance type
75-ohm unbalance type
Muting ON-OFF
MPX noise filter ON-OFF
<AM tuner part>
Circuit system 1 step of aligned type RF triple variable condenser
Practical speed (IHF, bar antenna) 300microvolts/m
Practical speed (IHF) 15 microvolts
Selectivity 40dB
S/N ratio 50dB
Image stonewalling ratio 65dB or more
IF stonewalling ratio 85dB or more
Antenna Ferrite bar-antenna adjunct
<Synthesis>
An Output voltage/impedance Fixed: 650mV / 4.7kohm
Variable: 70mV - 2V/300 ohm
Headphone: 150mV (8ohm)
The semiconductor used Transistor: 19 pieces
FET: Two pieces
IC: Four pieces
Diode, others: Nine pieces
Supply voltage AC100V, 50Hz/60Hz
Power receptacle Power-switch un-interlocking.: One line
Power consumption 27W
Dimensions Width 430x height 138x depth of 345mm
Weight 7.9kg