Category Archives: Accessories

Georges creates an IARU S meter scale for his Belka-DX

Many thanks to SWLing Post contributor, Georges Ringotte (F6DFZ), who writes:

When I did tests on my Belka-DX, I noticed that the signal level scale was extremely accurate, each mark is 10 dB

I regretted that the manufacturer didn’t use the IARU S meter scale. So I decided to make my own. With RF Gain to the maximum sensitivity, -73 dBm, or S9, is at the 45 mark. I used Front Designer software to make a scale, with 10 dB graduations above S9, and 6db graduations below S9.

Then this scale was printed on water based transfer, 40 mm by 26 mm, when applied on the existing display.

The result is great, and now I have precise readings of signals reports.

That’s brilliant, Georges! looks stock when applied to the screen!  Thank you for sharing this!

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Adi’s universal solution to various charging plugs

Many thanks to SWLing Post contributor, Adi, who writes:

Hi Thomas,

In one of the comments to your CC Skywave SSB 2 report I read, “Micro-USB is the worst connector ever” so I thought I might send you this solution, a magnetic cable

I’m using this on all my phones, tablets and radios.

One fits all and it works great.

Best regards, Adi

What a great tip. I suppose another benefit is the mag lock will break easily if someone trips on the charging cord. Might save a radio, tablet, or phone from a fall! 

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Checking out the Xiegu GNR1 Digital Audio Noise Filter

By Jock Elliott, KB2GOM

Call me a retro-crank, an old-schooler, but part of the joy of listening to shortwave is that the signals sound like they have come from far away. There is nothing like hearing the music, the news, the commentary “filtered through the shortwaves” . . . as Edward R. Murrow once put it.

At the same time, I am a content DXer (thanks David Goren for that phrase; it fits perfectly what I do).  Merely hearing some scratchy, barely audible signal won’t scratch the itch; I want to hear what is being broadcast clearly enough to make sense of it.

And when something particularly catches my ear, there are times when I would like to minimize the noise.

That’s where the Xiegu GNR1 Digital Audio Noise Filter comes in. According to the Radioddity website (they loaned me the unit for testing) —“The Xiegu GNR1 digital audio noise filter is an audio processing device integrating digital noise reduction and digital filtering. It can be widely used in the external audio processing sector of all types of wireless receiving equipment such as radio transceiver, receiver, radio, to effectively reduce the background noise, improve the signal-to-noise ratio, and improve the signal identifiable degree.”

What I found is a mixed bag. I had some difficulty getting the unit to work at first when I plugged my headphones into the headphones jack on the front panel. Once I plugged the phones into the SP #2 jack on the rear panel, I found the GNR1 will, indeed, reduce the noise on a relatively “fat” shortwave broadcast signal, rolling off the static with no digital artifacts and making the signal more pleasant for long-term listening. And you can use the high cut filter and low cut filter to tailor the sound to suit your ears, and they work quite well for that purpose.

On weaker signals, however, the GNR1 did not provide as much help in reducing noise or sometimes could not hear the signal at all.

For example, at my location east of Troy, NY, I can hear the Canadian time station CHU on 3330 nearly all the time. Today I could hear the time “pips” but down in the noise. I plugged in the BHI Compact In-Line Noise Eliminating Module (which I reviewed elsewhere), and I could hear the time station better, along the with the trickling water sound that is an artifact of the BHI noise reduction algorithm. But with the GNR1, it was as if the CHU time station had disappeared, no matter what adjustments I made to the device.

Bottom line, I can provisionally recommend the GNR1for reducing noise with no artifacts and tailoring audio on strong shortwave broadcast signals, but not for weak signals.

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Tom’s Recommendations: Earbuds and EQ Settings for Shortwave Listening

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

Earbuds for Shortwave Listening

by TomL

A few years ago I had bought the discontinued Sennheiser MM 50 earbuds for a cheap price on Amazon to use in my various radios.  The portable radios in particular can use more fidelity because of their small, raspy speakers.  I also like to listen without bothering others around me who might not want to listen.  And earbuds are a LOT more comfortable for my ear lobes than any over-the-ear headphones I have ever used.  Furthermore, the old Apple iPhone 4 earbuds were very harsh to listen to.  However, a trade-off is that, generally, earbuds are somewhat fragile; one of the two pairs of MM50’s died through mishandling.

I was generally happy with them while listening to Shortwave broadcasters with a mix of news/talk and music.  I especially liked them on Mediumwave listening; stations can sound surprisingly good when playing music.  Then I tried using these earbuds on my Amateur Radio transceiver, a Kenwood TS-590S.  I was impressed how clear they sounded with a lack of distortion, although there was too much bass.  Fortunately, Kenwood supplies USB connected software with an TX & RX 18 band EQ (300 Hz spacing, not octaves).

Here is a frequency response chart I found from for this model:

One of the notable things about these earbuds is the total lack of distortion.  Most likely one of the reasons they sound so clear on Shortwave, which has many LOUD audio spikes.

I had not wanted to get Bluetooth earbuds.  However, I had recently upgraded my cell phone and NO headphone jacks anymore!  So, while I do not use Bluetooth yet for radios, I can see a time in the future to get a Bluetooth transmitter to plug into a radio with a headphone jack.  I am reluctant since I do not like having to recharge my earbuds and I put in a lot of radio listening time.  Am I supposed to buy two Bluetooth earbuds and swap while charging?  Maybe in the future.  And also, am I supposed to buy a Bluetooth transmitter for every non-Bluetooth radio I own?  Not likely gonna happen.

In the meantime, I ordered cheap wired earbuds from Amazon.  I had a $5 credit for trying Prime, so when I saw these Panasonic ErgoFit wired earbuds (RP-HJE120-K) for slightly over $10, I said to myself, “why not?”.   Supposedly wildly popular, they are one of the most rated products on all of Amazon with 133,821 ratings/opinions (perhaps Russian bots?!?!?).

Here is a frequency response chart from for these Panasonic earbuds:

You can see comparatively that the bass response in the very good Sennheiser MM50’s is much stronger, being good music earbuds.  But for voice articulation, not as much, even though they have no distortion.  The Panasonic ErgoFit’s have more modest bass, less of a dip in the lower midrange audio frequencies, and more importantly, has a peak near 2500 Hz and its harmonic 5000 Hz.  The highest highs are also modest compared to the Sennheiser model.  This general frequency response to “recess” the bass and treble frequencies and peak the 2500 Hz is very useful for voice intelligibility.

As described by the famous speaker-microphone-sound-system maker, Bob Heil relates what he learned from the scientists at Bell Labs many years ago.  Speech intelligibility is enhanced when audio is compensated for our natural human hearing.  Equalizing below 160 Hz, reducing the 600-900 Hz region, and peaking the 2000-3000 region centered at 2500 Hz will increase intelligibility dramatically.  The story goes that Bell Labs was tasked by parent AT&T with finding out why the earliest phones in the 1920’s sounded so muffled and hard to understand.  After many experiments, the scientists found the most important frequencies for our ears + brain to comprehend speech.  In other words, our ears are not “EQ-flat” like a scientific instrument is. Continue reading

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One last call for SDRplay RSP1A metal cases!

Many thanks to SWLing Post contributor Dave (N9EWO) who writes:

Thomas, FYI decided to make one LAST production run of the RSP1A metal cases. These are now available on Amazon for $34.95 until stocks run out.

Dave Zantow N9EWO.

Click here to view on Amazon (affiliate link).

Thank you so much for the tip, Dave!

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The C.Crane Digital FM Transmitter 3

Many thanks to SWLing Post contributor, Ron, who shares information about the latest C.Crane FM transmitter:

Check out the new C.Crane FM Transmitter 3.

Everything is the same as the previous model except it now covers 87.7 to 108 MHz.

People have been reported as being in big trouble for using 87.7 MHz, or is it because of their competitor, the Whole House FM Transmitter? This also covers the entire band but has serious build quality defects according to the Amazon reviews and costs more than the C.Crane FM-3.

Click here to check out the C.Crane FM Transmitter 3.

Thanks for the tip, Ron! Like many, I use FM and AM transmitters to pipe Internet radio streams throughout my house: especially the UK 1940s Radio Station!

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