{"id":50013,"date":"2021-08-18T08:11:27","date_gmt":"2021-08-18T12:11:27","guid":{"rendered":"https:\/\/swling.com\/blog\/?p=50013"},"modified":"2021-08-18T08:11:27","modified_gmt":"2021-08-18T12:11:27","slug":"malahit-dsp-2-review-update-3-dan-evaluates-the-latest-hardware-version","status":"publish","type":"post","link":"https:\/\/swling.com\/blog\/2021\/08\/malahit-dsp-2-review-update-3-dan-evaluates-the-latest-hardware-version\/","title":{"rendered":"Malahit DSP-2 Review Update 3: Dan evaluates the latest hardware version"},"content":{"rendered":"

\"\"<\/a>Many thanks to\u00a0SWLing Post<\/em>\u00a0contributor,\u00a0Dan Robinson<\/a>, for the following guest post:<\/strong><\/b><\/p>\n

\n

UPDATE NO 3: Malahit DSP-2 (August 18, 2021)<\/h1>\n

A few weeks ago, I wrote<\/a> about my experiences with the Russia-made Malahit DSP-2 receiver, and made a recommendation that potential purchasers of the receiver hold off until the design team in Russia made some changes.<\/p>\n

Weak points included the SMA antenna connector \u2013 specifically the short cable going from the antenna to the PCB board, and sharp noise spikes seen at numerous locations throughout the spectrum from mediumwave up to 30 MHz.<\/p>\n

My particular DSP-2 unit went dead after an update to an early version of the 2.10TEST firmware.\u00a0 At the time, I had spoken via Skype with Georgiy on the Malahit team and kept up a string of communications on the Malahit Telegram channel.<\/p>\n

It was not clear to me whether the problem with the first DSP-2 was primarily due to SMA antenna issues or also due to a problem with the firmware update I had applied at the time (it was an early version of 2.10TEST).<\/p>\n

My appreciation goes to Georgiy who decided to send a new DSP-2 to me.\u00a0 This took about 3 weeks from the end of July until just recently when the receiver arrived (though the U.S. Postal Service made the end of that journey quite interesting).<\/p>\n

Here are some observations that I hope will help current and prospective owners of the DSP-2:<\/p>\n

SMA CONNECTOR<\/b><\/h1>\n

The Malahit team has made a change in the SMA cable \u2013 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.<\/p>\n

The new cable appears to be far more flexible than the old one, which was forced up against the inside of the receiver’s metal cabinet placing strain on the antenna connection to the PCB.\u00a0 I have been unable to ascertain, from the numerous messages going back and forth on the Malahit Telegram group, whether the development team intends at some point to replace SMA with BNC, which would obviously be a better choice.\u00a0 There is some useful discussion of the antenna connector issue on Telegram, and various persons are experimenting with BNC options.\u00a0 Georgiy and the team seem to be working on various physical changes to the DSP-2 cabinet and other firmware versions that are likely to be seen in coming months.<\/p>\n

FIRMWARE CHANGES<\/b><\/h1>\n

An excellent location to see firmware changes clearly, for those not yet hooked up via the Telegram group, is on this excellent site<\/a> which contains links to the latest FW updates and change log information.<\/p>\n

As can be seen from the change log, from July 24th the Malahit team took steps to address some key issues, including the failure of the battery icon to accurately reflect remaining voltage, and internally-generated noise.\u00a0 Improvements were also made to Synchronous mode \u2013 the receiver now enables lower and upper SYNC.<\/p>\n

Another change, implemented in the 2.10TEST FW version issued on August 16th, according to the Malahit team,\u201cimproved suppression of interference from the display. Now in SSB, AM, NFM modes, noise reduction is automatically turned on. This slows down the speed of the user interface, but greatly reduces the clutter! This function is not used in WFM mode.<\/em>\u201d<\/p>\n

REDUCTION OF INTERNAL NOISE<\/h1>\n

The major problem with the Malahit has been internally-generated noise.\u00a0 My first DSP-2 unit had numerous noise spikes, some appearing at inconvenient places in the middle of shortwave bands.\u00a0 One example was on or around 6 MHz where Radio Havana, Radio Mali and other stations are located.<\/p>\n

So, recent changes in firmware appear to have tackled this noise problem, to a degree.\u00a0 However, starting at the low end of the DSP-2 tuning range which is 50 kHz, noise spikes are still present, for example at:\u00a0 445, 625, 800, 980, 1160, 1340, 1875, 2055, 2230 and so on up through the lower part of the HF bands.<\/p>\n

After installation of the August 16th 2.10TEST firmware, the really loud noise spike seen at 6 MHz seems to have disappeared as has the noise spike at 12 MHz.\u00a0 Yet, noise spikes are still seen at 6,155 kHz, 6330, 6510, 6690, 6870, etc. at 180 kHz to 200+ kHz intervals.<\/p>\n

So, my conclusion is that while the changes to the firmware may have reduced the noise problems slightly, they still have not been able to resolve this issue and this is something that anyone contemplating a purchase of the DSP-2 needs to take into account.<\/p>\n

MISCELLANEOUS\u00a0 OBSERVATIONS<\/b><\/h1>\n

I have noticed what appears to be an increase in body sensitivity on the DSP-2 \u2013 signals improve sharply when hand touching the cabinet, and conversely fade fairly sharply without hand contact.<\/p>\n

As I said, this is more noticeable than before, especially when not using the PRE-AMP feature.\u00a0 With PRE-AMP engaged, signals are more audible when the receiver is left on its own.\u00a0 With PRE-AMP off, for example when listening to the usually strong signal on 12,160 kHz, programming can barely be heard.<\/p>\n

This video<\/a> shows a comparison between the DSP-2 and Afedri LAN-IQ Standalone receiver.\u00a0 Both units were placed in roughly the same receiving location, with the Afedri using a BNC-connected whip.\u00a0 The DSP-2 was using a somewhat shorter whip along with a 50 ohm impedance module, with the HI-Z setting on the DSP-2 set to OFF.<\/p>\n