Audio Database

Image of TX 8800 II
Commentary

An FM/AM tuner that improves reception performance and sound quality by introducing newly developed dedicated ICs at key points.

The FM front-end is composed of a four row varicon and a dual-gate MOS FET with low noise figure to obtain high sensitivity and interference rejection capability. In addition, the air gap of the varicon for local oscillation circuit is large to improve dial scale accuracy.

Wide / narrow 2-stage switching is adopted for the IF section, so that selection can be made according to reception conditions.
A newly developed dedicated IC (PA 3001) is used for this IF stage to improve the detection efficiency by making the detection stage low noise and low distortion, and to improve the tuning characteristics.
Narrow band has four 2-element ceramic filters for high selectivity while newly developed IC suppresses sound quality degradation. Wide band has only one 2-element ceramic filter for enhanced sound quality.

The MPX section does not filter out the 19 kHz pilot signal, but employs a pilot signal auto-cancel circuit using the newly developed MPX PLL IC (PA-1001) to reduce the high-frequency degradation caused by the filter.

The audio amplifier and muting circuit consist of a newly developed dedicated IC (PA-1002).
The de-emphasis circuit of this audio amplifier uses carefully selected elements such as a resistor with an error of 1% and a capacitor with an error of 2% to improve frequency characteristics.
In addition, the muting circuit that reduces inter-station noise and noise at the time of switch switching extends low-frequency characteristics by changing the low-cut filter of 10-odd Hz, which was conventionally used for eliminating pop sound, to 8 Hz by fast response switching in the IC.

A newly developed dedicated IC (PA-2002) is used for the power supply.

It has a built-in recording level check that sends out 440 Hz signal sound at the same level as FM50% modulation to the output at 1.6 second intervals. By setting the meter on the deck with this signal to -2 to 0 dB for the cassette and 0 to + 2 dB for the open-reel, FM broadcasting can be recorded in a wide band with high SN ratio.

The AM tuner section uses a double varicon and IC.

Four slide-type memory markers are mounted on the lower part of the dial face.

Equipped with an MPX noise filter.

In addition to two fixed and variable output terminals, a multi-path output terminal is mounted.

Model Rating
Type AM/FM stereo tuner
FM Tuner Section
Circuit system MOS FET RF1-stage 4-row varicon with IF BAND switching
quadrature detection, NFB method MPX
PLL with built-in pilot signal auto-canceler + double balance
Practical sensitivity Mono : 1.8 μ V/14.0 dBf (new IHF)
S/N50dB sensitivity Mono : 3.5 μ V/16.1 dBf (new IHF)
Stereo : 40 μ V/37.2 dBf (new IHF)
S/N mono:79dB
stereo:75dB
Harmonic distortion factor
wide narrow
mono: 0.1%(100Hz)
0.08%(1kHz)
0.1%(10kHz)
0.15%(15kHz)
0.15%(100Hz)
0.15%(1kHz)
0.15%(10kHz)
stereo: 0.15%(100Hz)
0.1%(1kHz)
0.5%(10kHz)
0.8%(15kHz)
0.4%(100Hz)
0.4%(1kHz)
0.9%(10kHz)
Capture ratio wide:0.8dB
narrow:2.0dB
Effective selectivity wide:35dB(400kHz)
narrow:80dB(400kHz)
60dB(300kHz)
Stereo separation wide:45dB(1kHz)
35 dB (50 Hz to 15 kHz)
narrow:45dB(1kHz)
30 dB (50 Hz to 15 kHz)
Frequency characteristic 20 Hz to 10 kHz ± 0.2 dB
20 Hz to 15 kHz + 0. 2-0. 5 dB
Image interference ratio 90dB
IF interference ratio 100dB
Spurious interference ratio 90dB
AM suppression ratio 55dB
Subcarrier ratio 72dB
Muting action level 5 μ V/19.2 dBf
Antenna 300 Ω Balanced Type, 75 Ω Unbalanced Type
<AM Tuner Section>
Circuit system Untuned RF1-stage, 2-train varicon
Practical sensitivity 300 μ V/m (bar antenna)
15 μ V (external antenna)
Selectivity 30dB
S/N 50dB
Image interference ratio 45dB
IF interference ratio 50dB
<General>
Output Level / Impedance
FM (100% modulation) Fixed : 650mV/4.2k Ω
Variable : 50 mv ~ 1.3V/3.6k Ω
AM (30% modulation) Fixed : 200mV/4.2k Ω
Variable : 15 mv ~ 400mV/3.6k Ω
Semiconductor used Transistor : 11
FET : 3
IC : 6
Diode, etc. : 16 pcs
AC outlet Power switch not linked : 1 system
Power supply voltage 100 VAC, 50Hz/60Hz
Power consumption 20W (Electrical Appliance and Material Control Law)
External dimensions Width 420x Height 150x Depth 392 mm
Weight 8.0kg