Pioneer TX-8900

Commentary

AM/FM stereo tuner with Rec level check function.

The front-end is equipped with a frequency-linear 5-row varicon and a low-noise dual-gate MOS FET (RFAmp. x2, Mixerx1). The sensitivity is improved by using a FET with a low noise figure and by increasing the gain of the next stage IF amplifier.

A buffer circuit is provided in the local oscillator circuit to improve stability, and there is no pull-in phenomenon even when there is an adjacent station with a strong electric field, and drift is suppressed.

The IF section consists of six 2-element ceramic filters with excellent phase characteristics and seven differential amplifier ICs. It is equipped with an 8-stage limiter, and the IF detection circuit of the control system is separated from the IF amplifier to achieve stable operation.

The detector of the IF section employs an ultra-wideband linear detector identical to that used in the TX 9900.
Since this detector has a bandwidth of 6 MHz and high detection efficiency, it is advantageous in terms of distortion reduction and signal-to-noise ratio, contributing to improved sound quality.

The MPX section uses a PLL method. The PLL does not degrade the separation characteristics even if there are changes in temperature and other factors, so it has stable characteristics.
It also incorporates a low-pass filter with sharp characteristics to prevent beat interference and intermodulation during FM recording.

It is equipped with a recording level check function. When this function is activated, a 440 Hz signal sound will appear on the sy power of the tuner at the same level as when FM50% is modulated for approximately 1.3 seconds. If you adjust the level so that this signal is located between -2 and 0 dB on the deck meter, the broadcast level setting will be almost correct.
In addition, this signal sound can be used for adjusting the phase of the speakers and balance check the left and right volume.

Equipped with a 2-step switching type muting circuit. This circuit also has a power supply muting circuit, so there is no noise when the power supply is turned on/off.

The AM section uses a 3-row frequency number line type varicon with dedicated ICs and ceramic filters.

It is equipped with an MPX noise filter to eliminate high-frequency noise that tends to occur when receiving stereo signals in weak electric fields.

It has two fixed and variable output terminals, multi-path terminals and four chMPX terminals.

Model Rating

Type	AM/FM stereo tuner
FM Tuner Section
Circuit system	MOSFET RF2-stage, 5-series variable capacitor, 8-stage limiter Ultra wideband detector, PLL MPX
Practical sensitivity	Mono : 2.5 μ V (S/N50dB) / 1.5 μ V (IHF) Stereo : 35 μ V (S/N50dB)
S/N	mono:80dB stereo:75dB
Harmonic distortion factor	mono: 0.15%(100Hz) 0.15%(1kHz) 0.15%(10kHz) stereo: 0.2%(100Hz) 0.2%(1kHz) 0.5%(10kHz)
Capture ratio	1.0dB
Effective selectivity	85dB(400kHz) 55dB(300kHz)
Separation	40 dB or More (1 kHz) 35 dB or More (50 Hz to 10 kHz)
Frequency characteristic	50 Hz to 10 kHz + 0. 2-0. 5 dB 20 Hz to 15 kHz + 0.2 -1.5 dB
Image interference ratio	110 dB or more
IF interference ratio	110 dB or more
Spurious interference ratio	110 dB or more
AM suppression ratio	55dB
Carrier leak suppression ratio	65dB
Muting action level	5 μ V/22 μ V
Antenna	300 Ω Balanced Type, 75 Ω Unbalanced Type
<AM Tuner Section>
Circuit system	Tuned RF1-stage, 3-series varicon
Practical sensitivity	300 μ V/m (bar antenna) 15 μ V (IHF)
Selectivity	40dB
S/N	50dB
Image interference ratio	65 dB or more
IF interference ratio	85 dB or more
<General>
Output Level / Impedance	Fixed : 650mV/5k Ω Variable : 70 mv ~ 2V/3.5k Ω 4 ch MPX : 400mV/2.5k Ω
Semiconductor used	Transistor : 34 FET : 3 IC : 11 Diode, etc. : 23 pcs
AC outlet	Power switch not linked : 1 system
Power supply voltage	100 VAC, 50Hz/60Hz
Power consumption	18W (rated)
External dimensions	Width 420x Height 150x Depth 365 mm
Weight	9.1kg