Tag Archives: SDR

Guest Post: An Introduction to DXing the MF Marine Bands

Many thanks to SWLing Post contributor, Don Moore–author of  Following Ghosts in Northern Peru–for the following guest post:


Monitoring the MF Marine Bands

By Don Moore

For me, DXing has always been about the challenge of receiving difficult-to-hear radio stations, regardless of the type of station or frequency range. In my five decades in the radio hobby I’ve logged a lot of different kinds of stations – shortwave broadcast, medium wave, shortwave utility, longwave beacons, etc. But some of my favorite catches have been in the upper end of the medium frequency range.

Technically speaking, medium frequency (MF) is the range from 300 to 3000 kHz and includes the standard medium wave (AM) broadcast band. The upper end of the MF band, from 1600 to 3000 kHz (except for a small portion reserved for amateur radio),  has always been assigned to various types of utility uses including broadcasts and other voice communications from regional maritime stations. And while digital modes and satellites have done a lot to change the nature of communication with ships at sea, there is still a lot of good human-voice DX to be heard.

Several dozen stations, mostly in Europe and North America, broadcast regularly scheduled marine information broadcasts in the MF range. These broadcasts are usually between five to ten minutes in length and include weather forecasts, navigational warnings, and other notices to keep ships at sea safe. On occasion it’s possible to hear two-way voice communication here between ships and shore stations, although that’s much less common today.

The Equipment

Nothing special is needed to DX the marine MF band other than a receiver that covers the frequency range and can receive USB mode (which all these broadcasts are in). However, for reasons explained below, I highly recommend using an SDR to make spectrum recordings of the entire band to go through later. Continue reading

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HFDY vs. Fire Brothers: Dan compares two Chinese Malahit SDR clones

Many thanks to SWLing Post contributor, Dan Robinson, for the following guest post and review:


Two Chinese Clones:   A Look at Noise Levels

Arriving recently here in the radio shack, were a Chinese clone under the name of “Fire Brothers” and another under the name HFDY.  I thought it would be constructive to note the key differences between these two clones, both of which are running Malahit 1.10c firmware, and post some video of a brief comparison.

A note in advance of any comments – I am primarily a HF listener so these comparisons do not cover frequencies above 30 MHz.  For those whose focus is on higher frequencies I recommend looking through the many comments on the Malahit Facebook group and Telegram by those who use these receivers in those ranges.

HFDY

  • Constructed of metal-like material (a correction from my previous articles that this is fiberglass of the kind used in printed circuit boards – thanks to Georgiy of Malahiteam for pointing this out)
  • Front speaker grille is gold color and appears to be metal but may be fiberglass as well – audio is quite good
  • Two top-mounted antenna jacks, one 50 ohm, the other Hi-Z (makes switching between HF and FM/VHF reception easier) with in-use LED indicators
  • Two high quality right side mounted black metal encoder knobs with large power button (clear printed Frequency/STDBY/Volume printed on panel)
  • Cabinet held together with TORX screws
  • 1.10c firmware
  • Receiver is elongated left to right to accommodate left side front-firing speaker, but is thinner overall and could be easily placed in a pocket though not recommended to prevent damage
  • Like every one of these SDRs, suffers from body sensitivity to touch which reduces signal levels unless some sort of additional ground is attached to cabinet
  • Internal flat-type Lithium battery of 3300 mAh though apparently capable of fitting up to 8000 mAh

Continue reading

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Dan adds updates to his Malahit SDR and variant reviews

Many thanks to SWLing Post contributor, Dan Robinson, for the following update to his previous post regard the DSP-2 and HFDY Malahit SDRs:


HFDY clone of the Russian-made Malahit SDR

Malahit and HFDY Updates

by Dan Robinson

HFDY CLONE:  As noted by a reader in comments, the Chinese-made HFDY leaves out a large portion of the military AIR band, with no coverage from 250MHz to 400MHz, or about 150MHz, whereas the Russian-made DSP2 only loses 20MHz from 380MHz to 400MHz.  This may be of concern for some readers, others not.

RUSSIAN DSP-2:  As users of the Russia-made DSP-2 may or may not have noticed, the current firmware shows SIX memory bank pages when there are only 5.  This appears not to have been discussed much on the Malahiteam Telegram group or elsewhere.  In response on this, Georgiy of Malahiteam says this “is normal and for our future features” so clearly there are future plans that we are not aware of.

CHINESE-MADE FIRE BROTHERS CLONE:  On September 21st, I took delivery of another China-manufactured clone, with a heavy metal cabinet, a vertical format with controls on top, and twin front-firing speakers.  Obtained via Alibaba, and branded as “Fire Brothers” this has a thick built-in telescopic antenna and a separate SMA jack which the maker describes as “[supporting] a better external shortwave antenna”

On Alibaba, prospective buyers of this receiver are given two options:  Type 1: 50KHz-2GHz without firmware updates supported, and Type 2 with support for updates.   The unit did arrive with 1.10c Malahit firmware with a 160 kHz bandscope width.

As noted above, this China-manufactured clone also blocks 200 mHz – 400 mHz and shows the Msi001 chip and STM32h743 and a claimed blocking figure of 85dB and  sensitivity up to 250MHz of 0.3?V = 10dB.  The battery is described as 5000 mAh and presumed to be flat type Lithium Ion.

The only thing included with this clone, which arrives in a plain black box marked “Fire Bros.Radio” is a USB-C cable.  That’s in stark contrast with the HFDY clone which comes in a high quality fabric zipper case, flexible whip antenna, USB-C cable, and a small metal stand.

The Fire Brothers manufacturer highlights the “high quality speakers” which not only fire out the front of the receiver, but also wrap around with openings on left and right sides of the radio.  My first tests show that audio is indeed quite nice, certainly equal to the Russia-made DSP-2, possibly an improvement on the HFDY clone which has a single front-firing speaker.

I’ll have more on this Chinese clone and some comparisons with the DSP-2, HFDY, and Afedri SDRs, in future articles here on SWLing Post.

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Malahit DSP-2 versus Chinese Clone: Taking the Gloves Off

Many thanks to SWLing Post contributor, Dan Robinson, for the following guest post:


Malahit 2 versus Chinese Clone: Taking the Gloves Off

New DDC (Direct Digital Conversion) Version in Development

by Dan Robinson

It’s been a few weeks since my last commentary on the Malahit/Malachite, which as of this writing remains at the DSP-2 level, though there are continuing hints from the Malahiteam in Russia about future changes, including a DDC version.

All of the observations I made in previous articles are unchanged.  As of today in mid-September, the latest test firmware version posted by the Malahiteam remains M2_FW2_10D.  This includes a widening of the waterfall bandwidth from 160 kHz to 192 kHz.  See my previous articles for more information.

Recently, I obtained a Chinese clone, one which will be familiar to anyone who has taken a dive into the clone market.  This one is by HFDY and is immediately recognizable for its front speaker and longer slim rectangular form factor.

The HFDY (Malahit SDR V 3) has two high quality black metal encoder knobs on the right, with a large power button between, and USB-C and a headphone jack on the left side.  On the bottom are two OFF/ON slide switches, one marked for 3.3 volts and the other BOOT(O).

Continue reading

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Malahit DSP-2: Dan’s thoughts on external antennas, firmware, and purchase decisions

Many thanks to SWLing Post contributor, Dan Robinson, for the following guest post:


Additional Thoughts on the Malahit DSP-2 

  • Potential for Noise Reduction Using Non-Whip Antennas
  • Latest Firmware Changes

by Dan Robinson

After my last update on the Russia-made Malahit DSP-2, I thought it important to add something about the receiver, as it could well influence those who may be on the fence about purchasing one.

In a series of communications, Georgiy at Malahit team has stressed steps taken to attempt to deal with internal interference seen across the bands.  And he has asserted

that noise spikes lessen if the receiver is connected to a non-whip antenna.

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.

Continue reading

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Malahit DSP-2 Review Update 3: Dan evaluates the latest hardware version

Many thanks to SWLing Post contributor, Dan Robinson, for the following guest post:


UPDATE NO 3: Malahit DSP-2 (August 18, 2021)

A few weeks ago, I wrote 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.

Weak points included the SMA antenna connector – 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.

My particular DSP-2 unit went dead after an update to an early version of the 2.10TEST firmware.  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.

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).

My appreciation goes to Georgiy who decided to send a new DSP-2 to me.  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).

Here are some observations that I hope will help current and prospective owners of the DSP-2: Continue reading

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Malahit DSP-2 Review Update: Dan recommends holding off until issues resolved

Many thanks to SWLing Post contributor, Dan Robinson, for the following guest post:


UPDATE: Malahit DSP-2 (July 24, 2021)

RECOMMENDATION: Hold Off Until Issues Are Resolved

I thought it important enough to write this update to my earlier extensive review of the Malahit DSP-2, the second version of the Russia-made receiver. Earlier incremental updates can be seen on the main article.

In concluding my main review, I spoke about being on the Malahit “train” and “roller coaster” – and my experiences since have shown that to be true.

As noted in one the updates, further testing confirmed the observations of Malahit users that when voltage of a 18650B battery drops below 3.7 v the receiver did indeed shut down. And the battery icon was still showing 50%.

Georgiy at the Malahit team confirmed this as a software bug, and in a test firmware update, the voltage issue was, according to him, corrected. The result, in a test firmware upgrade (2.10) could be seen with remaining voltage displayed in the battery icon itself. But I was unable to confirm that this actually resolved the issue of inaccurate voltage displayed before yet another problem emerged.

After performing the update from 2.0 to 2.10 Test firmware (more on that a bit later)
I thought things were fine until I noticed that all signals had vanished from the Malahit. This applied to the strongest signals from U.S. religious broadcasters, and down through FM.

In a combination of Telegram and Skype chats, Georgiy was extremely helpful – we went over seemingly every possible cause for this problem and focused on the SMA cable which from observing conversations online appears to be an issue in some units.

We went to the point of disconnecting the SMA from the PCB to test if anything brought back any level of signal, which it did not. With my basic knowledge of electronics, I believe that some problem may have developed on the PCB – whether that is directly related to the firmware upgrade process remains unknown.

On the firmware, the Malahit-recommended PC app is SMT32CubeProgrammer, which is easily downloadable, and instructions for the firmware update are on the Malahit You Tube channel. The process and app look difficult at first.

But things get interesting, as they always do, in using these Bootloader apps as I have found on several occasions in trying to upgrade my AFEDRI LAN-IQ.

Instructions on the Malahit You Tube channel direct you to power off the radio, then plug in a micro-USB cable to the receiver and to your PC. The rough Russian translation says push in and hold both main and smaller encoder knobs, and then press power either once or 3 times, and then watch for the LED to go off. The LED actually doesn’t really go off– in the process of the firmware update, flashes on and off.

I managed to get through the process of upgrading – it was quite smooth. The test 2.10 firmware according to Georgiy is supposed to correct the issue with voltage readings, though again I was unable to test this fully because my DSP-2 quite literally went quiet over its entire range.

As of now, and despite the best efforts of Georgiy which I appreciate, I have a dead DSP-2. Whether signal loss was due to some issue with the SMA connector, or whether the firmware process (I reverted back to 2.0 after noticing the signal loss) itself caused something on the PCB to fail, remains unknown.

Given all of this new information, and though I had made no BUY recommendation on my original review, I would have to advise anyone considering a DSP-2 to hold off for a while until the Malahit team is able to thoroughly iron out all the hiccups with the receiver, whether in firmware or hardware. This includes the question of the SMA connector, and the issue of voltage monitoring.

Based on the conversations that were taking place on Telegram, I would also be urging Malahit team to quickly come up with a clear English translation of the Malahit manual, and to review instructions contained in You Tube videos showing the firmware upgrade process.

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