Joined in 2023 
82 
63 About this deal
Sensitivity and selectivity are surprisingly top drawer; I am hard pressed to find much difference between my IC-7300 receiver and the Malahit-DSP. Performance in the ham bands is excellent as is in the AM broadcast band. From the components list we can see that this SDR runs on the MSI001 tuner chip, which is the same tuner chip used in the SDRplay line of units. However, unlike the SDRplay units which use a wideband MSi2500 ADC, the Malachite-DSP uses an audio chip as the RF ADC. This provides a 16-bit ADC, resulting in high dynamic range, but at the expense of the available bandwidth which is only 160 kHz. A STM32H743VIT6 with ARM Cortex A7 processor runs what appears to be custom DSP and GUI software. The software doesn't seem to support DRM, but AM, WFM, NFM, LSB, USB are all supported. I have observed in the past that most every portable receiver I have ever used exhibits touch sensitivity to a certain degree. Aside from the Afedri, the Belka DX has somewhat more immunity to this, likely due to its heavy metal cabinet construction. Even Tecsun receivers, especially the PL-990x and PL-368, have this annoying issue. I bought my Malahit receiver with multiple listening and use purposes in mind as I’m sure many others have. The Malahit team has made a change in the SMA cable – whereas before an extremely short length of wire attached the antenna to the PCB board, there is now a longer, though it appears even thinner, length of wire making that connection.
One piece of advice I have passed to the Malahit team involves QC (quality control) issues with the screw holes on the cabinet. On both my initial DSP-2 and the replacement, one of the screws did not insert smoothly in the hole threads. This is something Georgiy is aware of and says will be dealt with in a re-design of the cabinet, though no timeline is provided. Importantly that Georgi already released next generation of his radio DSP2 which he is selling now, with second board of automatic filters getting this radio to the next level. For my personal interests, the combination of a Malahit, Afedri SDR, and Belka DX for now fill all of my needs for experimentation with these small standalone radios. It will certainly be interesting to see where things stand at about this same time in 2022. But I had to offer up this comparison. Even with noise reduction efforts on the part of Malahit Team, in the end, you’re not likely to hear much more using a Malahit that you won’t hear also on a Tecsun 501x or similar recent portable – IF you’re a skilled operator with thorough knowledge of the bands. I have deliberately not connected my Malahit DSP-2 receiver to my central antenna system which uses Wellbrook and W6LVP loops feeding numerous receivers through a multi-port that maintains constant gain.
Most of my tests have used whip antennas of various lengths, in various locations indoors and outdoors, because it’s my view that portability is a major attraction of these small SDR receivers. The capacity of the ADC. I will go into this characteristic in a little more detail. Very often the ADC bitrate is used as a marketing ploy that is misleading the user. It is logical that the more the better. But as we see, even with a 14-bit DDC, a better dynamic than 16-bit DSP. And that's why not only the ADC capacity is important for classic or analog SDRs, but also the properties of the ADC radio path. If you use 24- or 32-bit ADCs in the Malachite DSP series, the radio receivers do not get any better - MSI001 does not allow this, in which case it limits the connection. So, you need to carefully analyze the build of radio receivers and not trust misleading promotions - many bits are certainly good, but you shouldn't forget the location of the ADC either. The main properties of radio receivers are determined in particular by the first input stages. Georgiy of Malahit team suggests that best performance on shortwave will be achieved with a normal longwire antenna, or a wire of at least two meters. Through a series of firmware updates, the Malahit team has been playing a cat and mouse game, attempting to reduce noise across the spectrum. At some point, a limit is reached in terms of what can be achieved with the existing design.
The designer is intent on removing all previous versions of firmware across the web in an attempt to force users to lake his licensed firmware that for many doesn't work I have mainly been using it for monitoring HF Amateur bands. The Scope's maximum bandwidth is only 160 kHz, but for HF that is certainly adequate. The Scope works brilliantly, however for me the most impressive thing is its Noise Reduction. Powerful functions: variable filter width, adaptive noise suppressor, threshold noise suppressor, Noise Blanker, AGC, equalizer, changed the behavior of the receiver with a short press on the power button. Now, with a short press in the receiver, the touchscreen is turned off, the spectrum and waterfall work similarly to the Pan & WTF Single option.I tapped on every menu option in every category. All work as advertised, even ones I did not fully understand. Noise reduction is extraordinary.
LCD connected to PCB with 3 times longer then original flat cable, making radio noisier from digital signals getting into RF and waterfall looks lot busier but reality is – it just own noise. The comparison results for the main characteristics are summarized in the table. The worst result of the comparison is marked in red, the best or neutral result is blue. The frequency range is different. This is the difference to specific design solutions. And the DDC has to catch up with the DSP version due to the additional board developed with converters. The additional board is already under development. I read about them for a while before taking the plunge, and certainly some Chinese clones are reported as being not up to scratch, however mine (badged 'Jstvro' on the front) appears to have no problems at all. Important to make sure its firmware is legitimate (registered). One could easily argue that the numerous signal processing and other flexibilities of the Malahit make that decision for you. While the Belka DX is superior in many respects, it lags behind the Malahit on sheer number of settings, though the Belka’s fixed processing positions are more than sufficient for superb reception on shortwave.
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At 3.6 volts current draw is 9 mA. The signal levels are very similar as with the original mini-whip at 12 V / 55 mA. Can the same be said about a Belka DX? Yes, and no. The Belka has a number of fixed settings which need to be mastered to get the most out of that receiver. But once accomplished, it produces excellent listenable audio, and acceptable sensitivity levels, in a short period of time whereas the Malahit requires considerably more fiddling. Its a shame these radios are so so widely and for so much to non specialists, as they represent very poor value for money unless you have the skill and time to upgrade them
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