DENON TU-850
¥ 70,000 (released in 1977)
Commentary
An FM stereo tuner that uses a new method developed by DENON acoustic researchers in pursuit of sound quality in the FM detection and stereo demodulation sections.
A drum type long scale dial is used for tuning.
A low-noise dual-gate MOS FET is used in the high-frequency amplification stage of the front-end section to obtain high S/N and interference rejection capability.
In order to achieve both the transmission characteristics for improving sound quality and the characteristics for eliminating interfering signals from the outside, the IF amplifier switches between wide-band and narrow-band characteristics. In addition, a sub amplifier system for the control system is provided separately.
In wide-band operation, the sound quality is improved by using a linear phase four element ceramic filter. In narrow-band operation, the number of filter elements is increased to further eliminate interfering signals, and selectivity is improved.
In order to improve linearity, the FM detector has wider characteristics than the conventional wide-band ratio detector. Moreover, by matching the impedance between the detector stage and the final stage in the IF section, the amplitude and phase characteristics are flattened and low distortion is achieved.
We have also improved the S/N ratio by more than 10 dB compared with conventional ratio detectors by using carefully selected silicon diodes as diodes, which are a major factor in determining the S/N ratio of the detector circuit, and by paying attention to resistors and transistors that generate noise in circuits used around the detector circuit. In addition, fixed bias is applied to the diode to compensate for the rise characteristics of the silicon diode, resulting in low distortion.
The MPX section uses a newly developed IC with superior distortion, separation, and S/N. In addition, the MPX beat elimination method using a unique PLL is employed to improve sound quality.
This system focuses on the problem that interference signals are generated near the pilot signal in the FM detector or other circuits when there is a mismatch between the connection between the antenna and the tuner, or when reflected waves (multi-path radio waves) mixed with the desired radio waves reach the tuner. This system extracts only the components that shake the pilot signal at the output of the phase comparator in the PLL, and cancels the shake with the inverted signal. This system greatly reduces the shake caused by interference signals very close to the pilot signal.
In addition, the newly developed IC incorporates a pilot canceler to reduce unwanted tone components and a 100% NFB circuit to improve distortion, thereby improving various characteristics.
Equipped with an oscillator for recording level check.
The level meter can be used to measure the power amplifier output level and multi-path.
You can measure multipath by connecting an oscilloscope or pre-main amplifier to the multipath terminal.
The high blend switch improves the S/N ratio when receiving stereo signals.
.JPG)
.JPG)
Model Rating
| Type | FM stereo tuner |
| FM Tuner Section | |
| Circuit system | Superheterodyne system |
| Receiving frequency range | 76 MHz to 90 MHz |
| Intermediate frequency | 10.7MHz |
| Practical sensitivity (IHF) | 1.7 μ V (9.8 dBf) |
| S/N50dB sensitivity | Mono : 3.3 μ V (15.6 dBf) Stereo : 30 μ V (34.7 dBf) |
| Effective selectivity | wide:35dB(400kHz) narrow:65dB(300kHz) |
| Image interference ratio | 120dB |
| IF interference ratio | 110dB |
| Spurious interference ratio | 110dB |
| AM suppression ratio | 65dB |
| Capture ratio | wide:0.8dB narrow:1.5dB |
| <Audio section> | |
| Frequency characteristic | 20 Hz to 15 kHz + 0.2 -1.5 dB |
| Carrier leak | 78dB |
| Signal-to-noise ratio | mono:84dB stereo:82dB |
| Total harmonic distortion rate (1 kHz) | Mono : 0.05% (wide), 0.1% (narrow) Stereo : 0.06% (wide), 0.3% (narrow) |
| Stereo separation | Wide : 55 dB (1 kHz), 45 dB (10 kHz) Narrow : 45 dB (1 kHz), 40 dB (10 kHz) |
| 19 khz and 38 khz suppression ratio | 80dB |
| Output Voltage / Impedance (at 100% modulation) |
Fixed : 1V/1.7k Ω Variable : 0 ~ 1V/1.7k Ω or Less |
| Level check voltage (440Hz) |
Fixed : 0.5 v Variable : 0 ~ 0.5 V |
| <level meter> | |
| External audio measurement range | + 10, + 20, + 30 dB (0 dB : 0.775 V) |
| Indication error | Within ± 0.2 dB |
| Frequency characteristic | 20 Hz to 15 kHz ± 0.5 dB |
| Dynamic characteristic | Conform to JIS C 1504 |
| <General> | |
| Connection terminal | Antenna : F-type connector (75 Ω), screw type (300 Ω, 75 Ω) Other : Multi-sensing terminal, audio output terminal, level meter external terminal |
| Pwer | 100 VAC, 50Hz/60Hz |
| Power consumption | 14W |
| External dimensions | Width 434x Height 164x Depth 400 mm (including leg, knob, terminal) |
| Weight | 8.9kg |
| Attachment | Connection code x1 F Type Stopper for 75 Ω 3C-2V x1 2 speaker cords One FM antenna |