Audio Database

TX 810 Image
Commentary

FM/AM tuner with high-integration IC equivalent to 203 elements and phase-linear ceramic filter.

In the front-end section, low-noise dual-gate MOS FETs are carefully selected and used in the RF stage and mixer stage to improve practical sensitivity.
In addition, a tuning circuit using a four link varicon improves the interference rejection capability.

The local oscillator circuit is equipped with a buffer circuit. Even when stations with strong electric field are adjacent to each other, the buffer circuit works to prevent unstable phenomena such as lead-in.

The IF section uses Pioneer technology to integrate 203 elements into one IC for IF.
In addition, the detection circuit uses quadrature detection, which has excellent linearity over a wide low distortion.
In addition, a phase linear ceramic filter has been adopted with an emphasis on phase characteristics within the passband.

The MPX circuit uses a high-integration IC to cope with SCA beat interference and separation, and features are improved by adopting a double-balanced differential demodulation method.
Carrier leakage is also reduced by using a low-pass filter that cuts harmful residual carriers at 19 kHz and 38 kHz.

A ceramic filter is used in the IF stage of the AM tuner section to obtain sharp slope characteristics with an appropriate bandwidth and improve selectivity and sound quality.
In addition, by adopting a high-integration IC developed exclusively for AM, stability at the time of strong input is improved.
In addition, the use of a balanced mixer eliminates distortion in the local oscillation waveform and improves spurious characteristics.

The AM section also improves the image interference ratio and IF interference ratio by adopting a tunable RF1-stage amplification using a 3-row varicon.

It is equipped with a muting circuit, and by the double action effect of semiconductor switching and read relay combination, transient pop noise during tuning is suppressed, and unpleasant shock noise during tuning is suppressed.

A new signal meter is used.
The input signal is taken from each limiter stage, detected by a level detector, passed through a DC amplifier, and added to the meter with a signal with good linearity on a gentle curve. This system accurately follows the input signal from the Oire power to the large input.

The headphone amplifier uses a Darlington OTL amplifier, and the volume level can be controlled by the front panel.

A multi-path terminal is mounted and used to select the antenna direction with the least mutual interference due to multiple reflection of sound waves.
By connecting a stereo display SD-100 or an oscilloscope, you can easily determine the best point in the antenna direction.

Equipped with an MPX noise filter that cuts noise when receiving an FM stereo broadcast transmission.

There are two types of output jacks, fixed and variable. The output level of the variable output jacks can be adjusted independently by FM and AM.

Model Rating
Type AM/FM stereo tuner
FM Tuner Section
Circuit system MOS FET RF1-stage, 4-series variable capacitor 6-stage limiter
quadrature detection
Practical sensitivity (IHF) 1.8 μ V
Capture Ratio (IHF) 1dB
Effective selectivity (IHF) 80dB
Signal-to-noise ratio 70dB
Image Interference Ratio (82 MHz) 90 dB or more
IF Interference Ratio (82 MHz) 100 dB or more
Spurious interference ratio 100 dB or more
AM suppression ratio 55dB
Harmonic distortion factor Mono : not more than 0.2%
Stereo : not more than 0.4%
Frequency response (stereo) 20 Hz to 15 kHz + 0.2 -2.0 dB
50 Hz to 10 kHz + 0. 2-0. 5 dB
Stereo separation 1 kHz : 40 dB or more
50 Hz to 10 kHz : 30 dB or more
Carrier leak suppression ratio 65dB
Antenna 300 Ω Balanced Type
75 Ω Unbalanced Type
Muting ON-OFF
MPX Noise Filter ON-OFF
<AM Tuner Section>
Circuit system Tunable RF1-stage 3-train varicon
Practical sensitivity (IHF, bar antenna) 300 μ V/m
Practical sensitivity (IHF) 15 μ V
Selectivity 40dB
Signal-to-noise ratio 50dB
Image interference ratio 65 dB or more
IF interference ratio 85 dB or more
Antenna Ferrite bar antenna included
<General>
Output Level / Impedance Fixed : 650mV/4.7k Ω
Variable : 70 mv ~ 2V/300 Ω
Headphone : 150 mv (8 Ω)
Semiconductor used Transistor : 19
FET : 2
IC : 4
Diode, etc. : 9 pcs
Power supply voltage 100 VAC, 50Hz/60Hz
Power outlet Power switch not linked : 1 system
Power consumption 27W
External dimensions Width 430x Height 138x Depth 345 mm
Weight 7.9kg