Kchibo D39L use experience, Radio Reviews


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DSP shortwave radio, after all, China’s first, just received the machine.

HF shortwave

In the short-wave receiving the same type of comparison should be taken to minimize variables, because the human ear’s memory is relatively poor, in the same content to be used in instantaneous comparison, so easy to identify (for each band to listen to various radio contrast).

1 Adjacent channel:

Machine Model —-/ reception conditions / monitoring conditions / receive location / receive time / reception frequency ——/ SNR show / field display ——/ frequency offset adjustment

D39L (DE1103) / rod antenna / D39L headset / indoor parity / 18:00 — / 5.90 and 7.325MHZ/25dB (no) / 50-60dBu (full frame) / plus or minus 5KHZ

Result — normal IF bandwidth D39L adjacent channel rejection are greatly exceed DE1103, narrow-band (the choice of 1103) the two planes adjacent channel rejection quite effective.

Conclusion — even if the DE1103 such high-frequency double-conversion superheterodyne radio tradition, if not used narrowband IF function, adjacent channel interference is greater than the DSP shortwave radio.

2 full-range

Machine Model —-/ reception conditions / monitoring conditions / receive location / reception time – / tuning mode —–

D39L (DE1103) / rod antenna / D39L headset / indoor with bit / 9:30-10:00 / full band automatic search

D39L received frequency / 1103 received frequency (MHZ):

3.945/6.105
6.03/9.345
6.105/9.685
7.19/9.72
7.28/9.83
9.345/9.86
9.50/11.62
9.66/11.64
9.685/11.695
9.72/11.735
9.83/11.795
9.86/11.835
11.62/11.875
11.64/11.885
11.695/11.925
11.735/13.61
11.74/13.65
11.795/13.815
11.835/15.10
11.875/15.245
11.885/17.83
11.915/21.58
11.925
11.98
13.58
13.61
13.65
13.76
13.815
13.97
14.60
15.10
15.17
15.245
15.36
17.645
17.83
21.58

Result — whole frequency automatic search D39L dominant, quite automatically search speed and 1103 (unpleasant), two sets of machine stops short wave sensitivity are just right, very little noise error signal received, D39L automatically search overcharged several frequencies, 1103 Manual also received, the receiving frequency to listen to all of the above results, D39L not under in 1103.

Conclusion — even if the DE1103 such high-frequency double-conversion superheterodyne radio tradition, rare in the short-wave (weak) time, full-range automatic reception can not exceed the DSP shortwave radio.

(Note: my first edition in 1103 under the Stop of the winter ambient temperature significantly decreased the sensitivity of the soft failure, the replacement of the four product wins 1800mAh automatically disappear after the snow cold temperature performance of normal)

3 alias:

Off frequency (false signals) is an interference signal, the interference signal can be received by those frequencies as interference points, which is N times by the radio local oscillator harmonic distortion produced by a combination of frequency interference if the interference point ( alias) appear in the normal radio broadcast signals (real frequency), the receiver will affect the real frequency (clip audio / rejection).

Made radio frequency interference common false (AM) is nothing but these types of short — short-wave interference (aliasing is generally outside the meter band) / MW interference with short-wave (usually in the UHF frequency of fake section) / MW interference wave ( leave the vicinity of L-band frequency in general) …

Here is what I received the machine, on different occasions, repeatedly use the manual tuning method compared with the DE1103 listening (rod antenna / headphones):

1 short-wave short-wave interference — the two planes are not found off-frequency interference point.

2 medium-wave interference false SW — D39L interference occurs at a frequency (MHZ): 2.945 (981KH) / 2.96 (1179KH) / 3.14 (981/1179KH) / 3.16 (1179/981KH) / 3.34 (1179/981KH ) / 3.535 (1179KH) / 3.67 (1179KH) / 4.46 (981/1179KH) / 4.55 (1179KH) / 4.685 (1179KH) / 5.415 (1179KH) 8.32 (1179/981KH) / 8.405 (1179/981KH) / 8.52 (1179 / 981KH) / 10.70 (1179KH) / 10.765 (1179KH) / 11.01 (1179KH).

3 long-wave — 1103 AM interference frequency interference occurs at a fake: 145KH (1044KH) / 279KH (1179KH )……

Description — 981KH the local broadcast of the Voice of China / 1179KH Yangzhou local news station (FM is 98.5MH).

Results — D39L strong in the medium wave broadcast environment (field strength at 70dB at) short-wave low-frequency (UHF section) appear combination of interference points (aliasing), interference points in the medium wave field strength is weak ./DE1103 broadcast strong environment (field strength at 70dB at) L-band interference near the point (aliasing), interference field strength strong point.

Conclusion — D39L strong Polish deal as long as the total field strength meter band outside of a minor under the combination of interference (certainly handle), the traditional high-frequency double-conversion superheterodyne radio would not be able to compete ./DE1103 order Polish thoroughly deal with the strong-field intensity near the L-band frequency interference with the enjoyment level off, probably will take time …

4 strong frequency:

Strong signal (frequency) is the capacity of short-wave radio to receive the important metrics that can receive radio signals to more strong, not self-excited, non-blocking, non-interference, no distortion, showing the HF side character.

The following is the unit I (Industrial Park) indoor substation with D39L paid part of the record:

Reception conditions (rod antenna) / listening conditions (D39L headphone) / receive time (19:50-21:20)

Frequency (MHZ) / SNR (dB) / field strength (dBu)

6.185—-/25——–/61
6.19—–/25——–/55
7.185—-/25——–/62
7.19—–/25——–/58
7.28—–/25——–/62
7.37—–/25——–/55
9.17—–/25——–/48
9.28—–/25——–/56
9.355—-/25——–/50
9.38—–/25——–/50
9.40—–/25——–/45
9.41—–/25——–/50
9.515—-/25——–/45
9.55—–/25——–/52
9.57—–/25——–/53
9.68—–/25——–/69
9.735—-/25——–/51
9.745—-/25——–/51
9.75—–/25——–/53
9.77—–/25——–/60
9.80—–/25——–/56
9.85—–/25——–/51
9.87—–/25——–/52
9.895—-/25——–/45
9.965—-/25——–/55
11.52—-/25——–/49
11.56—-/25——–/45
11.58—-/25——–/42
11.62—-/25——–/50
11.635—/25——–/40
11.69—-/25——–/57
11.71—-/25——–/65
11.715—/25——–/59
11.825—/25——–/54
11.895—/25——–/42
11.915—/25——–/53
11.945—/25——–/51
11.98—-/25——–/49
11.995—/25——–/68
12.04—-/25——–/57
12.10—-/25——–/52
12.12—-/25——–/41
12.14—-/25——–/40
13.40—-/25——–/51
13.625—/25——–/52
13.685—/25——–/55
13.775—/25——–/40
14.41—-/25——–/60

Description — strong signal refers to the frequency of the received IF signal to noise ratio of 25dB can often show, this is my D39L strong signal amplitude reference standard, which is Kairon DSP radio AMIF (S / N) can be displayed in the current limit value, only the intermediate frequency signal to noise ratio shows a maximum, the field strength will be greatest.

— In the indoor environment results received so many strong radio signal, and can coexist peacefully, and no whistle call.

Conclusion — DSP strong signal reception power short-wave radio particularly strong, non-conventional superheterodyne radio can not match.

5 weak frequency:

Weak signals (frequency) of the reception, shortwave radio is the most important selling point.

Machine Model —-/ reception conditions / monitoring conditions / receive location / receive time / reception frequency limit – / noise ratio show / display ——–/ adjacent field receiving frequency (19:30 )

D39L (DE1103) / rod antenna / D39L headset / indoor parity / 17:30 — / 2.85 and 21.84MHZ/5-10dB (no) / 6-20dBu (0-4 cells) / 7.125 and 7.13MHZ– –

Help – I choose a short band at a specific time lower / higher frequency radio records for reference, refers to the weak signal frequency received IF signal to noise ratio 10dB below shows often, this is my weak signal amplitude reference D39L standard, intermediate frequency signal to noise ratio shows the smaller, the signal is weaker.

Results — D39L weak signal reception limit of no less than the DE1103, resolution of more than DE1103, signal to noise ratio no less than DE1103 (normal IF bandwidth), the human body sensing very small.

Conclusion — even if the DE1103 such high-frequency double-conversion superheterodyne radio tradition, bar Expand all short-wave sensitivity DSP can not overwhelm the chicken.

6 Audio:

The gist of the radio sound design for electric acoustic frequency response frequency response services (voice frequency response service for the ears).

Even the best if not the true power frequency response to reproduce the broadcasting frequency response, the effect will be less than satisfactory listen.

Advanced bipolar transistor circuit radio sound as good as the ordinary radio tube circuit, a small speaker (volume) of high quality pocket radio as a large speaker (volume) of the ordinary radio, while the former electrical frequency response design is not worse than the latter, which does not depend on amplifier circuit, the key is the high frequency part of the radio and speaker terminal part.

D39L’s AM / FM radio with mixing tube part … with a similar differential characteristics of MOS field effect on the tube, the terminal for the first time using a dedicated DSP HF radio headset, making short-wave audio effects with all current bipolar transistor circuit different from traditional radio, which is my personal preconceptions, we carefully taste, use headphones, not the little horn.

DE1103’s AM radio / first frequency / in the first place has been pretty good (with a high-quality JFET), but with the D39L, the gap is still apparent. Expressed in audio clarity, fullness, balance , the degree of integration aspects.

Shortwave receiver with language-based, first of all to clear, natural, high intelligibility, I short-wave machine for DSP satisfied with the results of headphone listening, which is the only way to compare the sound with the smallest tube amp IC shortwave radio!

kchibo DSP-D39L 2 kchibo DSP-D39L 3 kchibo DSP-D39L 4 kchibo DSP-D39L


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