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- > When you touch your buttons, an electronics mutes the inputs of the power amplifiers, so there is no noise when you switch to the speakers!!! The mute function often remains ineffective due to the oxidized spring contact string built into the buttons. This also applies to the mains switch!!! < -
Оконечный усилитель собран на: 2 x Motorola TE1819 & Motorola TE1820 (BD 243B & BD 244B)
Country: Hungary
Manufacturer / Brand: Videoton; Székesfehérvár
Year: 1984/1985
Category: Broadcast Receiver - or past WW2 Tuner
Number of Transistors: 53
Semiconductors
Main principle: Superheterodyne (common)
Wave bands: Broadcast, more than 2 SW bands plus FM or UHF.
Power type and voltage: Alternating Current supply (AC) / 220 Volt
Loudspeaker: This model requires external speaker(s).
Power out: 70 W (unknown quality)
Material: Metal case
Model: Stereo Receiver RA 6363 S - Videoton; Székesfehérvár
Shape: Book-shelf unit.
Dimensions (WHD): 440 x 115 x 240 mm / 17.3 x 4.5 x 9.4 inch
Notes:
- Frequency Response: 20Hz to 20kHz
- Distortion: 0.1%
- Speaker Impedance: 4 to 16Ω
- Input Sensitivity: 2mV (mm), 200mV (line)
Net weight (2.2 lb = 1 kg): 10 kg / 22 lb 0.4 oz (22.026 lb)
Source of data: Original-techn. papers.
Hi-Fi stereo modular radio amplifier suitable for receiving K, R1, R2, R3, VHF (66-73 and 88-104 MHz) wavebands. It contains 9 integrated circuits, 44 transistors and 42 diodes. Volume control, with balance, treble and bass controls. Includes AFC, Broadband, Noise Canceling Circuits. Includes a stereo LED and a signal strength indicator. On FM bands, 5 stations can be preset and then selected at the touch of a button. You can connect 2 stereo recorders and a magnetic turntable to its input. You can record from the radio or turntable to a tape recorder or play back between the two tape recorders. Power consumption: without control: 30 W; at full control: 130 W.
Radio frequency data:
Antenna sensitivity:
KH: ≤ 200μV;
RH: ≤100 μV, URH mono: ≤1.9 μV;
VHF stereo: 40 μV.
Selectivity:
Wide band: KH: 36 dB; RH1: 30 dB; RH2-RH3: 28 dB.
Narrow band: KH: 18 dB; RH1: 14 dB; RH2-RH3: 12 dB. VHF: 40 dB.
Mirror selectivity:
KH: 30 dB; RH1: 14 dB;
RH2: 8 dB, R3: 4 dB; VHF: 54 dB.
KF interference ratio from antenna:
AM: 46 dB;
FM: 80 dB.
Frequency transmission:
in the AM band: 100-2,200 Hz (narrow band); 100-4,500 Hz (wideband);
On the FM band: 50-15,000 Hz (-3 dB).
Harmonic distortion in the FM band: ≤1%.
Signal-to-noise ratio:
AM band: ≥45 dB;
On the FM band: ≥55 dB.
Sound attenuation in FM band for stereo reception:
1 kHz: ≥30 dB;
At 10 kHz: ≥20 dB.
Pilot suppression: ≥46 dB.
Demodulation distortion:
on the AM band: 3%;
On the FM band: mono 1%; stereo: 1.5%.
AM signal suppression in the FM band: 38 dB.
Auxiliary suppression: ≥56 dB.
Effect of the noise canceling switch in the FM band: ≥40 dB.
Audio frequency data:
Frequency transmission:
from a tape recorder ± 1.5 dB at 10-40,000 Hz;
from a magnetic turntable at ± 2 dB: 40-30,000 Hz .
Signal-to-noise ratio:
tape input: ≥52 dB;
magnetic pickup input: ≥46 dB.
Hearing attenuation:
≥40 dB (1 kHz);
≥30 dB (10 kHz).
Intermodulation distortion:0.2%.
Power bandwidth: 40-20,000 Hz.
Harmonic distortion:
measured from high level inputs 0.5 V, 1 kHz: 0.1%;
measured from low level input 5 mV, 1 kHz: 0.15%.
Output power: 2x25 W sine, 2x35 W music.
Launched in 1983, the RT-302 is a small Hi-Fi tower radio amplifier. Akai AP-D 210 / C turntable, Akai CS-F 210 tape recorder, DC 2050 Espeakers, SA-7 stand belonged to the second generation tower. - > When you touch your buttons, an electronics mutes the inputs of the power amplifiers, so there is no noise when you switch to the speakers!!! < - The transistors were originally Motorola TE1819 and TE1820, which are equivalent to BD 243B, BD 244B. Its predecessor was the RA 6360 S, compared to which the exterior and electronics were modified at several points. Externally, the power switch has changed from a round button to a square one, the upper half of which is just an ornament, fixed. The field strength indicator Deprez has been replaced by a series of LEDs. The round LEDs for tuning and stereo reception have changed to square. Unlike its predecessor, it requires a minimum of 8 ohm speakers.
It was very popular in an age when the buyer had little choice but to listen to a little more demanding music in exchange for a reasonable amount of money. Many of the copies produced have survived the vicissitudes of a changing time and are still more or less successful. However, the model has some type errors. The input stage receives a signal that is too large, causing the output waveform to squared at 2/3 volume. The loudness function cannot be turned off. Due to the excessive depth of the physiological volume control, it produces a powerful sound even at low volumes, which not all neighbors like. - > The mute function often remains ineffective due to the oxidized spring contact string built into the buttons. This also applies to the mains switch!!! < - Another source of error is the BF 244 A type FET on the output stage modules, which is directly at its input. Later, the factory realized this fault and modified the circuit for later types with a different transistor or a resistor. But the transistors BC 337-25 and BC 327-25 for the mute circuit on the control module may also be faulty. However, the mumus has become the tuning FM tuner (and also for the models where this module is used). Numerous theories and attempts have been made to solve the problem, from the senseless replacement of trimmers to the stabilized setting of the required supply voltages to the replacement of the operational amplifier. The factory was also trying to fix the bug. It changed the values of some resistors and trimmers on FM modules manufactured after 1986. These are less prone to attenuation. There is no universal solution. Before repairing, it is advisable to check that the specified voltages are present at all. The specimen shown here keeps the taxes stable, its outputs are repair-free.
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