Pioneer F-780
¥ 49,800 (released in 1981)
Commentary
An FM/AM digital synthesizer tuner with improved interference rejection capabilities such as improved RF intermodulation characteristics.
A linear push-pull front end composed of a twin varicap and newly developed ID MOS FET is adopted for the front end part.
The tuning element varicap has been said to have a narrow dynamic range because the element itself tends to become saturated due to the tuning of the diode element compared with the varicon tuning. However, by adopting a twin varicap in the tuning part, the dynamic range is greatly improved and input characteristics equal to those of the varicon are realized.
In addition, a newly developed ID MOS FET with 8 dB higher element characteristics is adopted for the RF amplifier, which is a push-pull configuration.
As a result, the dynamic range is improved.
A quartz synthesizer system is used to capture FM broadcasting stations by applying the accuracy of quartz.
The local oscillation frequency is locked by comparing the phase of the divided local oscillation frequency with the reference frequency made by the crystal oscillator.
In addition, by adopting the pulse swallow method, the reference frequency, which was 12.5 kHz in the past, is increased to 25 kHz, and by moving it out of the reproduction band, there is no anxiety that the reference frequency remains in the signal line and becomes noise.
The detection circuit uses a pulse counting method that pulses FM signals and processes them digitally and accurately.
As a result, excellent linearity can be obtained over a wide range, so low distortion factor and high SN ratio can be achieved. In addition, the distortion factor characteristic does not deteriorate in low and high frequencies due to linear detection.
In addition, a linear multiplier is used for the second mixer circuit and a push-pull oscillator is used for the second local circuit to suppress the generation of beats.
Pioneer's original direct-through MPX circuit is used in the MPX section that separates the L and R stereo signals.
The structure is such that the signal itself does not pass through the active element, the necessary signal is output as it is, and the unnecessary signal is grounded. By this structure, the noise component and nonlinearity of the transistor itself, and the restriction of the input level are not affected, so the stereo signal with low distortion factor and high SN ratio can be obtained.
Equipped with 6 preset functions for each FM and AM.
It is equipped with AM/FM wide / narrow switching circuits that can be used for sound quality and selectivity according to radio wave conditions.
It has a built-in last one memory function that allows you to receive the same broadcasting station when you turn the switch on again after turning it off.
The back-up power supply circuit instantly receives the stored broadcasting stations.
Equipped with Rec level check function.
Model Rating
| Type | FM/AM Digital Synthesizer Tuner | ||||
| FM Tuner Section | |||||
| S/N ratio 50 dB sensitivity | Mono : 3.2 μ V, new IHF 16.2 dBf Stereo : 19.5 μ V, new IHF 37.2 dBf |
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| Practical sensitivity | Mono : 0.95 μ V, new IHF 10.8 dBf | ||||
| SN ratio at 80 dBf input | mono:92dB stereo:86dB |
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| Harmonic distortion factor |
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| Capture ratio | Wide:1.0dB Narrow:2.0dB |
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| Effective selectivity | Wide:40dB(400kHz) Narrow:60dB(300kHz) |
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| Stereo separation | Wide : 60 dB (1 kHz), 50 dB (50 Hz to 10 kHz) | ||||
| Frequency characteristic | 20 Hz to 15 kHz ± 0.5 dB | ||||
| RF intermodulation characteristic | 100 dB (2.5 MHz detuning) 85 db (800 khz detuning) |
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| Image interference ratio | 80dB | ||||
| IF interference ratio | 100dB | ||||
| Spurious interference ratio | 80dB | ||||
| AM suppression ratio | 60dB | ||||
| Subcarrier suppression ratio | 70dB | ||||
| Muting action level | 5 μ V (25.2 dBf) | ||||
| Antenna input impedance | 300 Ω Balanced Type 75 Ω Unbalanced Type |
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| <AM Tuner Section> | |||||
| Practical sensitivity | Bar antenna : 300 μ V/m External antenna : 30 μ V |
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| Selectivity | Wide:18dB Narrow:50dB |
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| Signal-to-noise ratio | 50dB | ||||
| Image interference ratio | 65dB | ||||
| IF interference ratio | 90dB | ||||
| <General> | |||||
| Output Level / Impedance | FM (100% modulation) : 650mV/1.1k Ω AM (30% modulation) : 200mV/1.1k Ω |
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| Power supply voltage | 100 VAC, 50Hz/60Hz | ||||
| Power consumption | 12W | ||||
| External dimensions | Width 420x Height 60x Depth 380 mm | ||||
| Weight | 4.5kg | ||||