Audio Database


DIATONE DA-F680/DA-F680S DA-F680: 42,000yen(around the 1978 time)
DA-F680S: 40,000yen(around the 1979 time)

It is the FM/AM tuner which adopted the lock tuning circuit.

In order to improve the detune characteristic, the lock tuning circuit is adopted.
This circuit operates in ±100kHz from an aligning point, and neither a THD nor a stereo separation gets worse within the limits of this.

The degree of selection of IF stage can be switched to WIDE and NARROW, and also it is considered as independent 2 block configurations.
At the time of WIDE, it operates as high S/N and a low distortion tuner by the newly developed four-element ceramics filter and composition of LC tuning circuit for phase compensation. Moreover, at the time of NARROW, it becomes the composition of four two-element ceramics filters, and operates as a high selection degree tuner.

The THD is raised by adoption of a discrete transformer or the new model PLL MPX IC.

Calibrator which can oscillate a 440Hz beep with the same output as the time of FM50% abnormal conditions is carried.
If this switch is turned ON in front of FM air check and it arranges in a range of 0±2dB in the input volume by the side of a deck, the recording in the optimal level is possible.

The discrete composition which uses seven transistors and two diodes is used for AM tuner part.

There were two kinds, DA-F680 which equipped the carrying handle for rack-mounted one, and DA-F 680S which has not equipped the carrying handle.


Rating of a mode
Form FM/AM tuner
<FM tuner part>
Practical speed 1.8 microvolts (10.3dBf)
The degree of effective selection (±400kHz) Wide:45dB
Capture ratio Wide:0.8dB
S/N ratio (stereo) Wide:77dB
Image disturbance ratio 85dB
IF disturbance ratio 95dB
Spurious disturbance ratio 90dB
AM oppression ratio Wide:60dB
THD (stereo, 1kHz) Wide:0.1%
Stereo separation (1kHz) Wide:50dB
Frequency response 30Hz-15kHz+0.5 -1.0 dB
An Output voltage/impedance 0V-1.5V/5kohm
<AM tuner part>
Practical speed (S/N=20dB, bar antenna) 100microvolts/m
The degree of selection (±10kHz) 35dB
S/N 55dB
Image disturbance ratio 50dB
IF disturbance ratio 40dB
THD 0.8%
An Output voltage/impedance 0-500mV/5kohm
Power source AC100V, 50Hz/60Hz
Power consumption 18W
Dimensions DA-F680: Width 480x height 154x depth of 400mm
DA-F 680S: Width 424x height 154x depth of 389mm
Weight DA-F680:7.9kg