KENWOOD KT-3030

Commentary

FM stereo tuner developed with the aim of overcoming "degradation of SN ratio in low receiving frequency" which is a neck of the synthesizer tuner.

Conventional synthesizer tuners are said to be able to maintain a constant frequency because they compare the phase of the local oscillation frequency and the reference signal using crystal precision. However, when the characteristics of the "frequency vs. tuning voltage" of the local oscillation circuit (VCO) were actually measured, a curve was drawn.
This curve becomes gentle around 90 MHz. Even if the tuning voltage fluctuates due to noise, it does not appear as a fluctuation of the reception frequency and it was relatively easy to obtain a high SN ratio. However, at a low reception frequency, the fluctuation of the tuning voltage noise appears as a large fluctuation of the reception frequency, causing the SN ratio to deteriorate extremely.
To solve this problem, we have developed and installed a direct-linear reception circuit incorporating new devices such as a parallel twin circuit using 12 varicaps and a new oscillation circuit using MOS FET, and succeeded in making the influence of tuning voltage swing linear over all frequencies.

The stereo demodulation circuit employs a direct pure decoder (DPD) that multiplies the detection output by a pure sine wave with no components other than 38 kHz.
Since a low-pass filter such as a clean reception filter is not included in the signal line, there is no phase rotation, and a clear stereo signal can be obtained while maintaining high separation.

The IF stage consists of a DLLD (Direct Linear Loop Detector) and DCC (Distortion Collecting Circuit). In particular, the DCC function has been further enhanced to cancel the second to fourth order distortion of the IF filter to achieve low distortion.
In addition, four stage switching of the IF band is adopted with emphasis on reception characteristics.

The RF selector enables direct switching in strong electric fields and distance switching in weak electric fields.
Even when there are close high power stations, interference such as RF intermodulation and intermodulation is suppressed and high-quality sound with excellent SN is extracted.

Equipped with REC calibration and modulation level meter.

It is equipped with a display and digital rotary tuning that can confirm the radio wave condition at a glance.

4-station program function convenient for recording messages, 16-station preset for multi-station FM, auto Chinese arrowhead control effective for long-distance stereo reception, multi-path terminal, variable / fixed output terminal.

Model Rating

Type	DLLD Super Synthesizer FM Stereo Tuner
Receiving frequency range	76 MHz to 90 MHz
Antenna impedance	75 Ω unbalance
Sensitivity (75 Ω)	Distance : 0.95 μ V/10.8 dBf Direct : 5 μ V/25.2 dBf
SN ratio 50 dB sensitivity	Distance Mono : 1.77 μ V/16.2 dBf Stereo : 22 μ V/38.1 dBf Direct Mono : 10 μ V/31.2 dBf Stereo : 100 μ V/51.2 dBf
Harmonic distortion factor (100% modulation)	Wide mono 100Hz:0.006% 1kHz:0.004% 50 Hz to 10 kHz : 0.009% stereo 100Hz:0.009% 1kHz:0.007% 50 Hz to 10 kHz : 0.03% Narrow mono 100Hz:0.02% 1kHz:0.01% 50 Hz to 10 kHz : 0.02% stereo 100Hz:0.03% 1kHz:0.02% 50 Hz to 10 kHz : 0.1%
SN ratio (100% modulation, 85 dBf input)	mono:99dB stereo:91dB
Capture ratio	Narrow:2.0dB
Effective selectivity (IHF)	Wide:70dB Narrow:100dB
Stereo separation	Wide 1kHz:71dB 50 Hz to 10 kHz : 60 dB 15kHz:50dB Narrow 1kHz:60dB 50 Hz to 10 kHz : 50 dB 15kHz:45dB
Frequency characteristic	20 Hz to 15 kHz ± 0.5 dB
Image interference ratio (84 MHz)	100dB
IF Interference Ratio (84 MHz)	110dB
Spurious interference ratio (84 MHz)	110dB
AM suppression ratio (65.2 dBf)	70dB
Subcarrier suppression ratio	75dB
Output Level / Impedance	FM (1 kHz, 100% modulation) Fixed Output : 0.6V/2.3k Ω Variable Output : 1.2V/1k Ω Multipath output Vertical Output : 0.05V/10k Ω Horizontal output : 0.6V/10k Ω
Power supply voltage	100 VAC, 50Hz/60Hz
Rated power consumption (Electrical Appliance and Material Control Law)	16W
External dimensions	Width 440x Height 88x Depth 326.5 mm
Weight	4.6kg