DIATONE DA-F15/DA-F15S
DA-F15 : ¥ 60,000 (around 1978)
DA-F15S : ¥ 59,000 (around 1979)
Commentary
FM tuner using quartz PLL synthesizer system.
Quartz PLL synthesizer system is adopted, and the local oscillation frequency is controlled by 100 kHz basic signal which is 1/64 of the high precision crystal (6.4 MHz) as oscillator. By this, it can accurately tune and lock in every 100 kHz between 76 ~ 90 MHz. Moreover, the frequency system of the local oscillator realizes high precision of ± 3 kHz (-10 ~ + 60 ° C).
In this system, since the frequency is always locked to the broadcasting station frequency, optimum values for distortion characteristics and separation characteristics are always obtained.
Using a lock indicator, it is possible to check at a glance which direction the free running frequency of the local oscillator is shifted by lighting up of 3 light emitting diodes.
The selectivity of the IF stage is a switching type of Narrow and Wide, each of which is composed of two independent blocks.
Narrow selectivity consists of four 2-element ceramic filters for a high selectivity tuner, and Wide consists of a 4-pole + 6-pole phase-linear LC filter for a high S/N and low distortion tuner.
Low distortion is achieved by adopting a 4-pole + 6-pole phase linear filter.
A newly designed differential transformer and PLL MPX IC are used to improve harmonic distortion, S/N, stereo separation, and temperature stability.
The front-end section improves stability by using carefully selected dual-gate MOS FET with low noise figure, precision 5-series varicon, balanced mixer, etc.
Built-in air check oscillator (calibrator).
There were 2 types, the DA-F15 with the rack-mount carrying handle and the DA-F15S without the carrying handle.
Model Rating
Type | FM stereo tuner | ||||
Practical sensitivity | 1.8 μ V (10.3 dBf) | ||||
Effective selectivity (± 400 kHz) | Wide:45dB Narrow:75dB |
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Capture ratio | Wide:0.8dB Narrow:1.3dB |
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S/N ratio (stereo) | Wide:77dB Narrow:73dB |
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Image interference ratio | 110dB | ||||
IF interference ratio | 110dB | ||||
Spurious interference ratio | 100dB | ||||
AM suppression ratio | Wide:65dB Narrow:55dB |
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Total harmonic distortion factor (stereo, 1 kHz) | Wide:0.08% Narrow:0.25% |
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Stereo separation |
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Carrier leak suppression ratio | 65dB | ||||
Frequency characteristic | 30 Hz ~ 15 kHz + 0.5 -1.0 dB | ||||
Output Level / Impedance | 0 ~ 500mV/5k Ω | ||||
External dimensions | DA-F15 : Width 480x Height 108x Depth 356 mm DA-F15S : Width 424x Height 108x Depth 345 mm |
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Weight | DA-F15:6.8kg DA-F15S:6.8kg |