Audio Database

TU-555
Commentary

FM/AM tuner using FET and 3-row varicon.

The FM front-end uses a 3-row varicon and FET in the RF stage to achieve high sensitivity.
The AGC circuit also improves the selectivity in a strong electric field.

The 4-stage IF amplifier and 3-stage limiter circuit provide a sufficient limiter effect, making it easy to receive signals in noise-prone areas and low-voltage areas in remote mountainous areas.

The power supplies for the FM front end, FM and AM sections are stabilized by a zener diode.
In particular, we have succeeded in eliminating the AFC circuit by fully compensating the temperature of the front-end station and minimizing the drift of the station station by stabilizing the power supply.

The FM multi-circuit employs a switching system with high stability and reliability.

The noise canceler replaces the conventional high-cut method and uses a method that can remove only the noise at the time of stereo reception without cutting the high-frequency audible range.

It is equipped with a muting switch that eliminates noise between stations and enables quiet channel selection.

An amplifier for meter and muting is specially installed, and a large meter is used for tuning instruction to make the pin-point tuning circuit easy to see.
For this reason, the center of the radio wave can be surely adjusted by making the tuning point sharp.

It is equipped with a pure electronic FM stereo / mono switching circuit. With FM-AUTO, when FM broadcasting changes from mono to stereo, the electronic switch automatically operates.
In addition, it is equipped with a stereo indicator that can confirm the stereo broadcast transmission.

Equipped with 300 Ω and 75 Ω 2-branch impedance terminals.
Since the FM antenna is equipped with both short-range and long-range attenuators, distortion-free reception is possible even in high-field areas.

The AM antenna uses a high-sensitivity ferrite bar antenna.
External antennas can also be used.

The output circuit is equipped with a switch capable of switching between High and Low levels so that it can be connected to any amplifier.
It also has a separation adjuster for FM multiplex.

There was a special wood case sold separately.

Model Rating
Type FM/AM Tuner
<FM Part>
Receiving frequency 76 MHz to 90 MHz
Sensitivity 2 μ V ± 3 dB (20 dB quieting)
2.5 μ V ± 3 dB (IHF)
Harmonic distortion factor Not more than 0.8%
Signal-to-noise ratio 60 dB or more
Selectivity 45 dB or more
Capture Ratio (IHF) 3.0dB
Image ratio 50 dB or more
IF Rejection 60 dB or more
Spurious Radiation 34 dB or less
Spurious response rejection 60 dB or more
FM stereo / separation 35 dB or more
Local / Ditto Local:attenuate 20dB
Distant:direct
Antenna input 300 Ω balance
75 Ω unbalance
<AM Department>
Receiving frequency 535 kHz to 1605 kHz
Sensitivity (IHF) 20 μ V ± 3 dB (1 MHz)
Image ratio 40 dB or More (1 MHz)
IF Rejection 60 dB or More (1 MHz)
Selectivity 20 dB or More (1 MHz)
Output Level / Impedance 1.5 V or More / 10k Ω or More
<General>
Attachment mechanism FET / FM front end
Dial tuning
FM stereo auto
FM stereo indicator
FM Local / Distant Switch
MPX Noise Canceler
Flywheel tuning
FM muting
Pinpoint tuning circuit
AM ferrite bar antenna
Output level adjuster
PB Series Pair Design
Power supply voltage 100 VAC, 50Hz/60Hz
Power consumption 10VA
External dimensions Width 292x Height 111x Depth 267 mm
Weight 3.9kg
Sold Separately Wood Case C-10