Category Archives: Radios

Guest Post: A synchronous detector crash course!

Many thanks to SWLing Post contributor, 13dka, who shares the following guest post:


Revisiting the Belka’s “pseudo-sync detector”: A sync detector crash course!

by 13dka

“It’s usually hard to assess whether or not a sync detector helped with a particular dip in the signal or not, unless you have 2 samples of the same radio to record their output simultaneously and compare.”*

That’s what I wrote about the “pseudo sync detector” in my review of the Belka DSP last year.

Since I was recently upgrading to the Belka DX in order to pass on the Belka DSP to a friend, I had briefly two examples of almost the same radio on the table at the dike. I tuned them to the same stations and recorded some audio clips with one radio on sync detector, the other in regular AM mode, to answer the question whether or not sync has “helped with a particular dip in the signal”. Then I thought that demonstration would be an opportunity to try an explanation on what exactly (I think) sync detectors are all about anyway, hoping to find a middle ground between “technical” and “dumbed down beyond recognition”.

The trouble with sync detectors

Perhaps no component of a shortwave receiver is surrounded by so much misconception and confusion as sync detectors. Full disclosure: Until quite recently, I had an, at best, vague concept on what they do myself. It seems it’s not so much that people don’t know how they work, what they actually do when they work is where the ideas often diverge. 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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Hidden connector on Tecsun PL-660?

Many thanks to SWLing Post contributor, Andy (G0FTD), who writes:

Thomas

Not sure if you’ve come across this, but earlier when I was cleaning my Tecsun PL660 and took the main tuning knob off the spindle, I discovered what looked
like 4 holes of a hidden connector behind it !

I just did a quick search around and I came across a piccy of the PCB on a blog
page here and yes there appears to be what looks like a small USB connector of some sort poking out the PCB where the VFO knob is. [Andy clarifies that he was trying to point out the area to look, but the pic appears to be from the opposite side, so you can’t see it.]

I can’t say that I’ve ever seen reference to it.

Maybe you or your readers might know ?

73 de Andy G0FTD

Thanks for sharing this, Andy. I am curious if that might be the port they use for firmware updates? Perhaps someone here can verify? I gave my PL-660 to a friend and no longer have it here for reference. Please comment if you have some info about this port.

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Radio Waves: Old Gen FM Radio, Radio Burst Model Challenged, Iceland WebSDR, and Ida Destroys WZRH/KVDU Tower

Radio Waves:  Stories Making Waves in the World of Radio

Because I keep my ear to the waves, as well as receive many tips from others who do the same, I find myself privy to radio-related stories that might interest SWLing Post readers.  To that end: Welcome to the SWLing Post’s Radio Waves, a collection of links to interesting stories making waves in the world of radio. Enjoy!

Many thanks to SWLing Post contributors Dennis Dura, Troy Riedel, Dan Van Hoy, and the Southgate ARC for the following tips:


FM Radio, the choice of an old generation (Hackaday)

Had the pandemic not upended many of this summer’s fun and games, many of my friends would have made a trip to the MCH hacker camp in the Netherlands earlier this month. I had an idea for a game for the event, a friend and I were going to secrete a set of those low-power FM transmitters as numbers stations around the camp for players to find and solve the numerical puzzles they would transmit. I even bought a few cheap FM transmitter modules from China for evaluation, and had some fun sending a chiptune Rick Astley across a housing estate in Northamptonshire.

To me as someone who grew up with FM radio and whose teen years played out to the sounds of BBC Radio 1 FM it made absolute sense to do a puzzle in this way, but it was my personal reminder of advancing years to find that some of my friends differed on the matter. Sure, they thought it was a great idea, but they gently reminded me that the kids don’t listen to any sort of conventional broadcast radio these days, instead they stream their music, so very few of them would have the means for listening to my numbers stations. Even for me it’s something I only use for BBC Radio 4 in the car, and to traverse the remainder of the FM dial is to hear a selection of easy listening, oldies, and classical music. It’s becoming an older person’s medium, and it’s inevitable that like AM before it, it will eventually wane.

There are two angles to this that might detain the casual hacker; first what it will mean from a broadcasting and radio spectrum perspective, and then how it is already influencing some of our projects. [Continue reading…]

New observations challenge popular radio burst model (Sky and Telescope)

Strange behavior caught by two radio observatories may send theorists back to the drawing board.

Fourteen years ago, the first fast radio burst (FRB) was discovered. By now, many hundreds of these energetic, millisecond-duration bursts from deep space have been detected (most of them by the CHIME radio observatory in British Columbia, Canada), but astronomers still struggle to explain their enigmatic properties. A new publication in this week’s Nature “adds a new piece to the puzzle,” says Victoria Kaspi (McGill University, Canada). “In this field of research, surprising twists are almost as common as new results.”

Most astronomers agree that FRBs are probably explosions on the surfaces of highly magnetized neutron stars (so-called magnetars). But it’s unclear why most FRBs appear to be one-off events, while others flare repeatedly. In some cases, these repeating bursts show signs of periodicity, and scientists had come up with an attractive model to explain this behavior, involving stellar winds in binary systems.

However, new observations by European radio telescopes may rule out this model.

Astronomers knew that FRB 20180916B, located in a galaxy some 475 million light-years away, produces multiple bursts about every 16 days, during a ‘window’ that lasts for a few days. “The idea was that the magnetar is part of a binary system with a 16.29-day period,” says Inés Pastor-Marazuela (University of Amsterdam), the first author of the new paper. If the companion star had a thick stellar wind that absorbs radio waves, the bursts would only be visible when the magnetar was on ‘our’ side of the orbit, she explains. [Continue reading…]

New WebSDR in Iceland (Southgate ARC)

Iceland’s IRA reports on August 24 Karl Georg Karlsson TF3CZ connected a new receiver over the internet covering 24-1800 MHz

A translation of the IRA post reads:

QTH is Perlan in Öskjuhlíð in Reykjavík. These are Airspy R2 SDR receivers for 24-1800 MHz (on VHF and UHF). The antenna is a Diamond D-190.

Karl Georg stated the following on FB:
The extension is not just for 2m, it can only be on one band at a time. So if one user switches, others who are connected also move between bands. (However, you can listen to each frequency within the same band). The receiver automatically tunes to APRS QRG 144.800 MHz, see the APRS website: http://SDR.ekkert.org/map

URL of the receiver
http://perlan.utvarp.com/#freq=24890000,mod=usb,sql=-150

Thanks to Karl Georg for his valuable contribution. This is an important addition for radio amateurs who experiment in these frequency ranges, as well as listeners and anyone interested in the spread of radio waves.

IRA Board

Source Iceland’s national amateur radio society, the IRA
https://tinyurl.com/IcelandIRA

WZRH/KVDU Tower Destroyed By Hurricane Ida (Radio Insight)

The nearly 2000 foot tower utilized by Cumulus Media Alternative “Alt 92.3” WZRH LaPlace and iHeartMedia Variety Hits “104.1 The Spot” KVDU Houma LA was toppled by the winds of Hurricane Ida.

The 1999 foot structure was constructed in 1988 to host both signals. Only the bottom 150 to 200 feet remain standing. Both stations are licensed to operate with 100kW/591m, but have low powered auxiliary sites in downtown New Orleans. WZRH is located on the roof of Place St. Charles with 630w/200m. KVDU is on the Hancock Whitney Center with 1.2kW/220m.

In addition to KVDU, iHeartMedia Gospel 940 WYLD is silent at its cluster. The company reports that the remainder of its signals are now operational after all but 93.3 KQUE and 98.5 WYLD-FM were off the air on Monday.

Cumulus Media states that its entire cluster of WZRH, Adult R&B 102.9 KMEZ Belle Chasse, Country “106.1 Nash-FM” WRKN Picayune MS, and Hot AC “106.7 The Krewe” KKND Port Sulphur LA are off the air. [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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Bob Colegrove on “The Joys and Challenges of Tuning Analog Radios”

Many thanks to SWLing Post contributor, Bob Colegrove, who recently shared this excellent article and has kindly allowed me to share it here in the the Post. Bob prefaced it by saying, “Being a retired technical writer, I started the attached article some time ago for my own amusement, but it quickly got out of hand.

“Got out of hand” in a very good way, Bob!

An excerpt from Bob’s article.

I love how this piece takes us through receiver history and explains, in detail, the mechanics and innovations. It’s also a very accessible piece that both the beginner and seasoned radio enthusiast can appreciate.

But don’t take my word for it, download it and enjoy!

Click here to download The Joys and Challenges of Tuning Analog Radios as a PDF.

Thank you again, Bob. This is a most enjoyable and informative read! This was obviously a labor of love. Thanks for sharing it with our radio community!

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Guest Post & Review: Test Driving the Russia-Made Malahit DSP-2

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


 

Test Driving The Russia-Made Malahit DSP-2

Poised on Edge of Greatness?  (Some Challenges To Overcome)

by Dan Robinson

By now, the Malahit SDR is well known in listening hobby circles.  We have the made-in-Russia original, and those manufactured in China with various firmware and some physical differences such as location of the tuning encoders.

News about the Malahit began to spread in 2019, with articles here on the SWLing Post, including two in February and April of 2020 (https://swling.com/blog/2020/02/the-malahit-dsp-a-potential-holy-grail-portable-sdr/ and one in which the Malahit was put up against an Afedri LAN-IQ SDR (https://swling.com/blog/2020/04/fenu-posts-a-malahit-dsp-afedri-lan-iq-head-to-head-comparison/ ).

At the same time, we saw the development and appearance of the Belarusian Belka SDR.  I consider the latest Belka DX to be the ideal portable – a sensitive diminutive miracle that has become a must-have device for many of us.

As for the Afedri LAN-IQ, I held off on purchasing one until the “Standalone” version was available.  It is made in Israel by a Russian developer who supports the receiver with fairly frequent firmware revisions (though upgrading remains a bit of a challenge involving some obscure boot-loading software).

I waited and observed reviews of the original versions of the Malahit.  When its designer, Georgiy (RX9CIM), announced availability of the new DSP-2 version of the receiver, with expanded coverage to 2 GHz and a claim of improved performance, I finally purchased one.

As was observed in one of the early SWLing Post articles “It seem[ed] the project is open source, the schematic, PCB and software are available to download. . . we hope [these] receivers become popular and available world wide [and that] this new project “shakes” a bit the industry of shortwave receivers.”

Malahit project authors RX9CIM George, R6DAN Vladimir, and R6DCY Vadim, had the apparent objective of “designing a low-cost portable SDR radio, using only easily obtainable components and to become the natural successor of the popular Degen and Tecsun radios.”

At the time, the price for a finished Malahit, with an ARM chip at its center was about $195 US.  Coverage was to 1 GHz – this has since been extended to 2 GHz.  Synchronous AM mode was added, and the DSP-2 also comes with an internal battery tray for a single 18650 Li-on battery.

This is a change from the original flat Li-on cell, and in my opinion a welcome one  since 18650s are easily obtainable.  Being able to easily change out a battery is important, rather than messing around with soldering (the famous Reuter Pocket receiver made in Germany should take a hint).

In this age of the SDR, we’re all familiar with the SDRplay series and various AirSpy receivers, along with other SDRs such as the RX666/888.  Before that, we had the famous Perseus, which still has a strong following, and numerous WinRadio receivers.

See the articles here on the SWLing Post assessing the performance of these, as well as reviews at eHam.net, and numerous SDR dongles all over eBay, coming from China.  There is also an SDR group on Groups.io.

Of course, receivers and transceivers with panoramic displays began to appear some years ago – the ICOM IC-R8600 and IC-7300 are examples of how this technology was integrated into the listening and amateur radio markets.

What we had not seen was integration of this kind of technology into portables.  Even in its latest iteration, the Belka DX has a small screen without any PAN display.  So, the advent of the Malahit has made this kind of advanced display widely available.

The price, by the way, for my DSP-2 as of July 2021 was 19,500 Russian rubles, with an extra 2,000 rubles for express delivery via Russian Post (though due to COVID Georgiy stressed that no guarantees could be made as to timing).  That’s $263 – not a small investment and rivaling the cost of a Tecsun ATS-909x and H-501x.

According to the description I received when ordering, the Malahit DSP-2 was improved over the previous version with the following differences:

  • Frequency range – from 50 kHz to 380 MHz, and 400 MHz to 2 GHz
  • Improved RF shielding and hardware improvements to reduce interference
  • Changes in software functions
  • Dimensions changed to 140x 88x 39mm
  • 18650 battery

The DSP-2 is in a thin black metal cabinet with dimensions 5 x ½ by 3 x ½ by 1 x ½.

A power button and headphone jack are on the right along with a power LED.  On the top, we find the SMA antenna input, and a small telescopic whip is included.

The speaker, capable of some decent audio, is located on the inside rear of the receiver – audio level exceeds that of the Belka DX with its very small speaker, but the Belka has a clarity that often exceeds the Malahit.

My first testing of the DSP-2 was indoors, in a far corner on the top floor of my home, using just the included whip antenna.   For comparisons, I used a Tecsun PL-368 with its whip antenna and a Belka DX in the same location.  I find that indoor testing tends to identify some issues that would not be apparent outdoors.

In this, the Tecsun PL-368 and other Tecsun portables consistently performed best, followed by the Belka DX and the Malahit.  This may be surprising, but shows that radios specifically designed for shortwave reception, often provide better reception because they are matched better with their internal telescopic antennas.

Now, when I say “best” I mean best basic audio quality, using auto-memory and ETM functions on the PL-368 and 990x.  But what those radios can do with the signal after that point is pretty limited – there is no NR (noise reduction), you’re limited to a handful of set bandwidth selections, and SYNC mode leaves much to be desired.

Which is where the Malahit comes in with its numerous levels of flexibility, accessed through MENU icons on the lower part of the screen:  HARD, AUDIO, VISUAL, NR, MODE, and BAND.  I refer the reader to the Malahitteam site links showing the user manual (this is still a bit in the rough, with translation from Russian) and another link with a Quick Start guide written by John Pitz (KD8CIV).

KEY HIGH POINTS ON MALAHIT

SUPERIOR COLOR DISPLAY

The color display, also seen on numerous China-made clones, is the best on any handheld SDR.  Where the Belka LCD is a basic utilitarian tool that performs well for that receiver, the Malahit display is an invitation to the wonderland of what this receiver offers.

At the top are small icons for:  SQ, NB, NR, AGC, ANT, PRE, MODE.  Right of center, and controlled with pushes of the small volume encoder knob, are ATT, VOL, FILTER, and the battery icon.  Below those are headphone and speaker icons and an excellent, if small, frequency window.  Pushing the small encoder knob selects/controls volume, attenuation, and main filters.  The large tuning knob, with a press, selects step increments.

EXCELLENT NOISE REDUCTION

Noise reduction on the Malahit is superb, as many users have observed.  It’s activated directly with a front panel icon and Threshold is adjustable with an icon under AUDIO, with 0 to 30 increments.  NR is so good that I compare it with the latest firmware version on the ICOM IC-R8600 – it’s actually probably better than the ICOM even near and at the highest 30 level.

EXCELLENT FILTERING

Whereas the Belka DX offers fixed audio filtering values accessible via its front panel, the Malahit DSP-2 offers continually variable LOW FREQUENCY adjustment from 0 Hz to 2350 Hz, and HIGH FREQUENCY adjustment from 100 Hz all the way up to 150,000 Hz.   This is in addition to standard NARROW, NORMAL, and WIDE filter options selectable with the volume encoder knob.  This is nothing short of extraordinary for a handheld portable receiver.

The latest (and possibly last) Tecsun receivers offer set value multiple bandwidths, which is excellent but is a throwback to radio design from years ago.  So, the DSP-2 capabilities can be compared to the kind of filtering that a Watkins Johnson or Cubic receiver have, but in the palm of your hand.

As I often observe, what we would have given in gold to have this kind of capability in consumer receivers during the glory days of international broadcasting!

AGC / MGC FLEXIBILITY

The Malahit allows the listener to use AGC, with choices of SLOW, MEDIUM, and FAST.  But it also allows, again through the AUDIO settings menu, control of AGC GAIN 0 to 60, and AGC LIMITER 40 to 90 db.  Wow – priceless!  So even if you prefer, as I do, to listen to shortwave using AGC, you still have amazing flexibility.  You can still switch to MGC with 0 to 60 range.

NOISE BLANKER FLEXIBILITY

Just as the Malahit delivers on AGC, so does it deliver with its regular noise blanker function.  With NB activated, there are 3 configurations with a separate THRESHOLD icon adjustable for each of these.  Amazing.

RF GAIN FLEXIBILITY

RF GAIN is adjustable from 0 to 59, and there is a separate icon for adjusting gain for the PRE-AMPLIFIER.  Where the PREAMP comes in very handy is when one has the Malahit indoors – it provides a more sensitivity in situations where one is using the telescopic whip antenna, though care must still be taken not to overload the receiver and distort signals.

FCORRECT FUNCTION MAKES FOR EASY RE-CALIBRATION

The Fcorrect function located under the HARD settings menu enables one to re-calibrate the receiver to correct for error.  This is similar to the capability that Tecsun added to its 330, 909x and 501x receivers (there are indications Tecsun has or will enable this ability also in the PL-368) but seems, based on my testing of the Malahit to be more effective.  After I corrected my DSP-2 to about +57, calibration was pretty much on the money up and down the HF bands.

SQUELCH FLEXIBLITY

The Malahit not only has SQUELCH, but SQUELCH THRESHOLD control, another example of the tremendous flexibility in this receiver’s firmware.  Since I do not do much listening outside of the HF bands, or have the antenna for it, I have not extensively tested the Squelch above 30 MHz and up to the maximum range at 2 GHz.

There is yet another feature described as adaptive noise canceling that allows the user to significantly improve the intelligibility of the received station under conditions noise and interference.

[From the manual]:  The squelch uses different algorithms [depending] on filter bandwidth.  With a bandwidth of more than 1 kHz, a squelch of more than suitable for speech type signal.  With bandwidth less than or equal to 1 kHz, the squelch is suitable for tone type signals.  Choice of algorithm is carried out automatically, depending on bandwidth.  Meanwhile, squelch for speech signals can be used with NR (see further details on this in the manual).

FM RECEPTION WITH RDS

What the Belka DX lacks, namely reception of the FM range, the Malahit delivers in droves.  FM sounds excellent to me, on the same level perhaps of the Afedri LAN-IQ Standalone receiver.

RDS is enabled by touching the waterfall area of the display which brings up the RDS information.  The speed with which station information appears varies depends on position of your antenna and signal level.

As one user (Harold Hermanns) on the Facebook Malahit group observed:  “ I don’t think it works very well. I just checked mine, and went to about 25 stations. The RDS or station name came up on only 5 stations. Letters I get are PS, PT, and PTY. When you tune a strong station, give it a minute or so, that’s what I did, and the RDS feature does work, but again, it’s not 100%.  Maybe will be improved with firmware?”

The RDS information could be better organized – currently the name of the station, and name of the program scrolls on different lines.  Another touch of the screen brings up an old style FM scale – this is nice, but I prefer the PAN display.  Yet another touch returns the screen to the PAN display and waterfall.  Mode options include NFM and WFM, and another option provides FM-STEREO.  Also in FM, there is an auto-search function and station labeling

MISCELLANEOUS FEATURES

There are some other features in the mind-boggling list of options in various menus:

  • In FM (WFM) there is an eight position EQUALIZER function with SOFT, LIVE, CLUB, ROCK, BASS, JAZZ, POP, and VOICE positions.
  • A voltage monitoring function allows the user to turn off the receiver when voltage drops lower than 3.3 volts.  As explained in the manual this is intended to preserve battery life and avoid full discharge.
  • Antenna selection can be 50 ohms or Hi-Z (preferred for telescopic antenna use).
  • As the Malahit manual details, internal gain of the receiving chip can be adjusted.  Accessed from the HARD menu, this is too much for me to go into here, but it’s another example of the detail that went into designing the Malahit.
  • Brightness of the display backlight is adjustable as well as time after which backlight level is reduced to minimum and turned off completely.  Rate of change of the display spectrum is adjustable as is spectrum display range, color, ratio of waterfall and speed and brightness of waterfall.  Spectrum scale and view are adjustable.
  • There is a 5 page memory system, with M1 to M10 in each, so a total of 50 storable memories.

LOW POINTS OF THE MALAHIT

NOISE FROM THE DISPLAY

Example of noise on 1,000 kHz

As I was testing my Malahit DSP-2 it quickly became clear that there is one major low point, and thus a challenge for Georgiy and other members of the design team.

There’s no other way to say this:  internally-generated noise remains the major issue keeping the Malahit from achieving greatness.

 

The developers of the Russian version receiver have not attempted to hide this, and users noticed it from the beginning, with one writer identifying “internally generated noise, which peaks at various frequencies” as one of the key drawbacks of the Malahit.

I had hopes that the DSP-2 version of the Russian-originated Malahit might have less of this problem.  There are numerous internally-generated noise/buzzing spikes, some stronger than others, by my estimation at intervals between 125 and 200 kHz throughout the HF bands.

Example of noise on 6,000 kHz (RHC)

In the case of one huge noise spike appearing at or around 6,000 kHz – right over Radio Havana – it ruins any chance of hearing clear signals at, below and above that point.  As you can see in my video, the Belka DX does not have this problem (note: apologies for mis-spelling Malahit as Malachit).

VIDEO: Malahit With Display Generated Noise

Click here to view on YouTube.

Via Telegram, Georgiy asserted to me that when using an external antenna, noise is not as serious, and notes differences between the Malahit and Belka.  The Belka, he says, is a simpler device that concentrates only on shortwave, while Malahit is a wide band receiver with more complex DSP and user functions.

“When Belka cannot receive something, Malahit can.  And where Belka does not have noise, Malahit has it.  These devices are in different classes.”

The result is that a major workaround is often necessary – to disable the VIEW PAN&WTF option, a key feature that is a major highlight of the radio.

Georgiy says that this problem is mainly linked to telescopic antenna antenna operation because of the antenna’s proximity to the display.  But as you can see in my video, when testing the Malahit and Belka on 6,000 kHz it’s a night and day situation.

A quick push of the power button blanks out the display completely – and seems to completely resolve the noise issue.  But you don’t buy a radio to see a dark display, and it’s depressing to think that turning off a major feature, namely panoramic display, has to be part of standard operating procedure.

When testing the Malahit from its bottom frequency of 50 kHz, even with the PAN & WTF off, huge buzzing noise spikes are heard.  In mediumwave/AM, they are seen at  615 kHz, 790 kHz, 965 kHz, 1140 kHz and so on.

If a radio had emerged from a known large manufacturer with this issue, such as Tecsun or Sangean, it would have been roundly condemned by users and reviewers and sent back to the drawing board.

Georgiy does say that in the new firmware interference from the display was decreased, with a “step of about 2.5 MHz, from 1MHz (i.e. 1MHz, 3.5MHz, 6MHz).  After correction it will be with a step [of] 4 MHz”.  I’m not quite sure what he’s saying with this, due to language issues, but the overall indication is that he is aware of  this issue and will continue trying to tackle it in future revisions.

CW DECODING

In the MODE section of the Malahit there is no confirmation that the receiver is actually in CW.  Decoding is enabled with an icon, but again no confirming icon at the top of the display.  This is a bit odd.

Going to the Telegram app discussion group for the Malahit, and re-reading the translated Russian manual, I discovered that confirmation of CW appears as a white bar under the SPEAKER/HEADPHONE icon on the right.  There is also a MINIMUM SNR option in decoding, with a 0 to 70 range.

A You Tube video (the Gerry DX channel) shows the decoding process and notes that it’s important to keep the filter setting at NARROW when attempting to use the decoding feature on the Malahit and also important to set the SNR at the right level.

One would think that this could be easily rectified, but adding a CW indicator to the top row of small icons on the front display might not be as easy as one thinks, unless the display can be modified to also display “CW” in the icon spaces for AM, LSB, or USB.

It turns out that CW decoding on the Malahit works quite well, at least in my attempts.  I was able to decode fairly strong CW signals in 40 meters.

LCD/TOUCH SENSITIVITY

When I first got the Malahit, I was puzzled by what seemed to be a serious lack of sensitivity on the display when trying to use the touch icons to change configurations and modes.

This was so bothersome that I raised it with Georgiy who responded that this is by design.  The present capacitive touch method, he says, is preferable and more comfortable for users.   “If [we were to] change the touch [enable faster response] then [some] people will demand to decrease it.”

With benefit of some time, I have concluded that a slightly firmer and longer press of about half a second to a second almost always brings up the menu selected.  But this is definitely a characteristic of the DSP-2, so potential owners should be aware of it.

ISSUE WITH CLOCK

Another issue that prospective purchasers should be aware of involves instances where the internal clock of the receiver does not retain the time, and the solution for this directly from Georgiy is not necessarily satisfactory.

“Yes, they need to be removed from the PCB” he says, a reference to two capacitors on the main PCB, C29 and C30 which are next to each other below a larger M7 device on the PCB.

These are SMDs so anyone without good soldering skills will be hard pressed to want to mess around with that PCB.  This is not a confidence-builder, nor a solution – clearly these receivers should come from the supplier without such an issue.

This was upsetting enough for some users that the Malahit team faced some sharp criticisms.  One user said the clock on his DSP-2 was working perfectly.  Another said: “Unless I power off the unit the date stays good but the time is always 2 hrs and 10 minutes behind. As soon as I power off the unit the date defaults back to 15:08:2062.”

One user said:  “Problem is voltage is very inaccurate causing the clock settings to be lost. I have tried several 18650 batteries (good Panasonics) and fully charged they are 4.2v, but the DSP-2 indicates 4.6v. When the battery runs down to 4.0v the clock settings are lost. Also, the battery indicator continues to show FULL. I think there is an internal problem with the DSP2. Perhaps the new design, or new internal parts are causing this. This is very disconcerting.”

In exchanges on Telegram, Georgiy said he personally checks each outgoing Malahit for sensitivity on each band, and clock operation, among other things.  In a later comment just before this article went to press, Georgiy said that C29/C30 should be replaced only if there is a problem with the clock.

There is no mention by the Malahit team of any official return policy – which of course would be quite challenging and costly involving an additional round trip for a receiver back to Russia and then back again to the user.

On my DSP-2, which I have used with an Anker 26800 USB battery, so far my clock/date settings have maintained accuracy with no reset, even after the USB cable is unplugged from the receiver.  I have not yet tested longer times to see if the clock/date is reset when voltage drops below a certain point.

[UPDATE: 22 July 2021]

In a message sent after publication, Georgiy says that the C29 and C30 capacitors will be deleted from the next series of the Malahit, and for now they are being removed from receivers that have not been sold yet.

[UPDATE 23 July 2021]

Further testing revealed that the observations of Malahit users are accurate. When voltage of a 18650B battery in my Malahit dropped below 3.7 v the receiver did indeed shut down — this is with the battery icon still showing 50%. So this is definitely an issue that needs to be addressed in future updates. That said, I got hours of operating time before the full 18650 dropped to the cutoff level — but obviously an inaccurate battery icon is something that the Malahit team will have to correct.

THE BATTERY GAME

Example of 18650 rechargeable batteries

The Malahit DSP-2 uses a 18650 Li-on battery.  Unfamiliar to many people, these are actually well known among professional-grade flashlight collectors/users (flashlight collecting is another of my vices).

One of the first things I realized when my Malahit arrived was that my existing button top 18650 cells were too long to comfortably fit in the battery tray.  A bit of research on the Facebook Malahit group page revealed that some users have modified the receiver to take two 18650 cells, with a double tray replacing the single tray.

The original Malahit tray requires shorter “unprotected” flat top 18650 cells.  At the time I write this, there is a shortage of these cells at the major battery / flashlight suppliers (Battery Junction is one).  DO NOT try to force a slightly larger 18650 in the stock Malahit battery tray!

So, one recommendation I would make to the Malahit Team in Russia would be to make it possible for the receiver to use regular protected button top 18650s, of the type one would easily use in a Tecsun receiver such as the 909x and H-501x.

However, in a message to me just before this article went to press, Georgiy said that the Malahit team has used “typical holders” available to them and that they had been unable to obtain a sufficient number of alternative trays for protected 18650 button top batteries.  So, for now at least the Malahit will require unprotected flat tops.

My 18650B flat top batteries arrived just as I was completing this review – easily charged up in my Littokala charger, each then fit easily in the single battery tray and power the Malahit perfectly.

ENCODER KNOBS

Higher quality replacement knobs

The original encoder knobs on the Malahit can be replaced by higher quality, metal construction ones for the small and larger knobs.  I got mine from Nikolay, a member in Russia of the Malahit Facebook group (he says he sources them from Switzerland, but I have not confirmed this).

I am, however, not sure that the new knobs can simply be installed on the Malahit – there are no set screws on the original plastic Malahit knobs and I chose not to mess around to see whether the metal knobs can easily be installed, at least for now.  Price for the higher quality metal knobs:  $17

[UPDATE 23 July 2021]

Nikolay Vedeneev in Russia produces high quality encoder knobs for the Malahit, Afedri, and Belka SDR receivers. He can be reached at: nickstrannik@gmail.com and received a very positive review from Fernando Duarte who is known for his reviews of numerous receivers. Both of his knobs fit perfectly on the shafts of my Malahit DSP-2 and have a much better feel than the originals (NOTE: I used a 1.5 mm hex key to tighten the set screws) https://fenuradio.blogspot.com/2020/07/custom-tuning-knopfe-fur-jedes-gerat.html

VIDEO

Click here to view on YouTube.

POISED ON THE EDGE OF GREATNESS

The subtitle of this article asks whether the Malahit is poised on the edge of greatness.  I believe it is, but anyone’s choice to join the Malahit user/fan club comes with some headaches.

We can only hope that the Malahit team can work on the problem of noise spikes that permeate the lower frequency ranges from mediumwave on up.  There’s no way to minimize this:  at $263 (the price of a DSP-2 as of July 2021) buyers should not have to be shutting off the display to eliminate noise.

As for the question of the clock on the DSP-2 not maintaining time/date, etc it’s clear that Georgiy and the Malahit team are aware of this issue and one hopes this could be checked off the list of concerns that users have raised.

Whether one needs all the bells and whistles that a Malahit offers is the major question, especially when the Belka DX offers excellent stepped (not continuously adjustable) audio filtering and a form of synchronous AM detection in what has to be the smallest high performance receiver ever available to the listener.

More than a few Malahit owners have observed that between 1.5 MHz and 30 MHz the Belka DX seems to be the better shortwave receiver, with no display noise issues, superb battery life and an amazing small size that makes it the ultimate ultra-portable.

In short, if you choose to step aboard the Malahit train you enter a world where there will be constant improvements in software and hardware, and bugs along the way, of which noise spikes issue is a perfect example.  But if you’re someone who gets enjoyment from being on the leading edge of technology in radio development, the Malahit may be for you.

It’s impressive that the Malahit originated in Russia, not generally been known for innovations at this level.  In recent years, Asia was the main source of advances from the likes of ICOM, Yaesu, AOR etc in the amateur radio area, and from Tecsun, Sangean, and Eton in the area of portable receivers for HF listeners.

Finally, one has to wonder about the potential that the Malahit design holds for integration into the kind of portables seen over the past two years.  Some observers have asked why the LCD display and other features on the Malahit could not be part of a future receiver that looks like a Tecsun 990x or Sangean 909×2 with additional advances such as off-air microSD recording, and DRM.

FINAL ASSESSMENT:  I boarded the Malahit bus fairly late, but I am definitely a fan.  Owning one of these receivers is indeed a roller coaster – anyone climbing on should become a member of the Facebook and other discussion groups where users exchange views, suggestions, and their own experiences.

For ultimate portability in 2021, the Belka DX wins the race.  But the Malahit wins on the sheer number of advanced signal processing and other features it contains, though it is hobbled to an extent by the problem of display interference.

If Georgiy and the Malahit team can continue to make steady progress in confronting the noise issue and fine tune the already amazing array of features, the Russia-made Malahit has a bright future ahead.

[UPDATE 24 July 2021]

In the latest firmware update to the Malahit DSP-2, Georgiy provides this
changelog. Note that this is still described as “TEST” firmware, so it’s still unclear
whether he intends to put out a non-TEST version of this particular upgrade:

Firmware 2.10 TEST:

  • fixed battery voltage indication
  • fixed behavior of encoder buttons at low supply voltage
  • protection against false switching has been made – for switching on by three, set switch 2 to the On position.
  • added test function – increased display frequency. This reduces noise and increases the number of frames per second; To enable this function, set switch 3 to On. The function may not work correctly, if so, please let me know
  • the level of interference from the display is slightly reduced
  • changed the distribution of frequencies to which the input high-pass filters are turned on
  • when HiZ is turned on, the power supply of the external active antenna is automatically turned off;
  • added indication of external antenna power on – now the ANT indicator is highlighted in red if this function is enabled
  • the algorithm for displaying the picture on the display, slightly reduces the level of interference
  • changed the panorama display mode from “Pan & WTF Disabled / Enabled” to “Pan & WTF Single / Always”, while the panorama image is now always present, but it is updated once (when the settings are changed) or always.
  • fixed attenuators bugs

[UPDATE 2, 24 July 2021 ]

Please read this updated post explaining why I believe you should hold off on making the DSP-2 purchase until software and hardware issues have been resolved.

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