Pioneer TX-6600II

Commentary

FM/AM tuner with improved reception performance and reduced distortion.

The FM front-end uses a high-frequency single-stage amplifier circuit composed of an FET with low noise figure and a frequency number line type 3-row varicon.

The IF stage uses an IF dedicated IC developed by Pioneer that combines elements of more than 200 elements in total into one IF stage. In addition, two 2-element ceramic filters with excellent phase characteristics are used as selection elements to enhance interference rejection capability.
In addition, this circuit has a 5-stage limiter and waveform shaping, which greatly reduces AM noise.
In addition, the TX 6600 II is equipped with an interstage amplifier using a single transistor between the ceramic filters of the IF stage in order to enhance the practicability. By increasing the gain and ensuring a flat phase characteristic, the tuning characteristic is improved and the increase of distortion and degradation of separation are suppressed even if there is a slight tuning deviation.

A PLL circuit IC is used in the MPX section to stabilize the separation characteristics of the MPX section, which is easily affected by temperature and humidity, and a 5-element full-fledged IC filter is used as a low-pass filter to improve the characteristics.

It has a built-in muting circuit composed of three transistors to cut out noise such as pop noise when tuning or detuning, noise between stations, and click noise when switching power ON / OFF or selector switch.

The AM tuner uses a high-integration dedicated IC.
This IC has excellent AGC characteristics, which ensures almost constant operation regardless of whether the input is strong or weak. As a result, stable sound quality with less distortion is obtained in both strong and weak electric field regions.

The three point selector switches, FM-Auto, mono and AM, are lever type combined with ON-OFF of the muting circuit.

The meter on the front panel functions as a center tuning meter for FM reception and as a signal meter for AM reception.

Model Rating

Type	AM/FM stereo tuner
FM Tuner Section
Circuit system	FETRF 1-stage, 3-series varicon, 5-stage limiter, quadrature detection, PLL MPX
Practical sensitivity	Mono : 1.9 μ V/14.0 dBf (new IHF)
S/N50dB sensitivity	Mono : 2.8 μ V/14.0 dBf (new IHF) Stereo : 44 μ V/38.0 dBf (new IHF)
S/N	mono:75dB stereo:68dB
Harmonic distortion factor	mono: 0.15%(100Hz) 0.15%(1kHz) 0.2%(10kHz) stereo: 0.3%(100Hz) 0.3%(1kHz) 0.6%(10kHz)
Capture ratio	1.0dB
Effective selectivity	60dB(400kHz)
Separation	40dB(1kHz) 30 dB (30 Hz to 15 kHz)
Frequency characteristic	30 Hz to 10 kHz + 0. 2-0. 5 dB 20 Hz to 15 kHz + 0.2 -1.0 dB
Image interference ratio	60dB
IF interference ratio	90dB
Spurious interference ratio	75dB
AM suppression ratio	50dB
Subcarrier ratio	62dB
Muting action level	1.7 μ V/10dBf
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	35dB
S/N	50dB
Image interference ratio	40dB
IF interference ratio	70dB
<General>
Output Level / Impedance	FM (100% modulation) : 650mV/4.6k Ω AM (30% modulation) : 150mV/5.4k Ω
Semiconductor used	Transistor : 8 FET : 1 IC : 3 Diode, etc. : 9 pcs
Power supply voltage	100 VAC, 50Hz/60Hz
Power consumption	12W (Electrical Appliance and Material Control Law)
External dimensions	Width 380x Height 139x Depth 322 mm
Weight	5.6kg