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MK 1.5 ‘Andrus’ review in Finland DX magazine

William Straus 15. August 2016

Finland DX magazine Radiomaailma http://www.sdxl.org/rmsisalto.html wrote a review about the MK1.5 ‘Andrus’.

Below is the conclusion part translated from Finnish.

Pros

  •  Device is extremely sensitive, on the level of NF 10dB;
  •  It has NetSDR-compatible LAN network connection with max bandwidth of up to 400kHz;
  •  USB connectivity with ca 200kHz bandwidth;
  •  Overall frequency stability is very good, +/-5Hz stabilization level stays up for 10 minutes;
  •  Price/quality ratio is extremely good (Andrus=370€ vs. Perseus=850€ vs. NetSDR=1500€);
  •  Two external antenna connectors allow so-called diversity receiving (no program supports this feature);
  •  A number of programs to use (part of those being developed yet as well), for example HDSDR, SDR-Radio 1.5/2, SdrDX, CuteSDR, Linrad;
  •  Opensource firmware.

Cons

  •  Wideband front-end given possibility of inband IMD spurios signals;
  •  Sensitive to outside voltage peaks what come in sight on the waterwall;
  •  There were some internal noise signals visible as well (like a combined interference);
  •  Too high gain of front-end stage (reparable!);
  •  Narrow-band reception store max 400kHz frequency segment in the LAN-network connection;
  •  Signal level reading on the S-meter is not realistic (too high);
  •  Problematic power connector.

Summary

Andrus MK1. 5 is a good mid-range receiver. With small imperfections, it is a functional entity that can be recommended for e.g. beginners DX listeners or those who are otherwise interested in SDR technology connoisseur. In my opinion the ratio of price/quality of that device is excellent. For recording medium-wave frequencies, Andrus is unfortunately unsuitable due the fact that its current bandwidth is nowadays in the maximum only by 400kHz LAN network connection. However, sensitivity of the medium wave listening can be found – in the device medium waves are not supressed as those are in some ICOM receivers. In my tests with Andrus, the weakest link turned out to be ungrounded, floating antenna connection and the surprising sensitivity to noise peaks from outside of the device. In another situation the listening position could certainly be different and the device inside the “Antenna ground” earthing switch P5 (ANTGND) Interference may try to suppress. Somehow it was accompanied by the SDR, the internal bias repetitions (comb interference), as well as strong positions IMD interference results, which may in turn be suppressed reducing Andrus’ front end gain. The next version of the interference level should however, perhaps to sacrifice a little bit more time and to better protect the device RF front end. Small ground terminal could fit on the rear panel in line with other connectors. Sensitivity and selectivity in favour of Andrus is almost comparable to NetSDR reads, the difference between the benefits is actually quite small. This is due to the fact that the software used for testing was the same (SDR- Radio 1. 5). In terms of the signal duration Andrus remains second in this comparison. Its ADC circuit dynamics allows digitally adjustable pre-amplifier with 123 dB without AGC of 80 dB range.  However, AGC works only in a relatively narrow band of listening (e. g., 6 kHz – 6 dB). For example – when the receiving bandwidth is 400 kHz, then received signals of stations outside of that 6 kHz bandwidth do not affect the AGC level – and dynamics can thus will only be at that 80 dB. Simon Brown’s SDR- Radio Version 2 is only in beta stage, but upon completing it gets really good program Andrus to be used. Also, a number of different programming options can be found for narrowband USB port. Firmware and software updates in the future will increase the receiver unit’s (hardware + software) level of quality. Andrus MK 1. 5 is, therefore, recommended SDR receiver – but it is currently the smallest at the moment, with the above observations.

 

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