Tag Archives: LW

Addendum: More Notes on the HF+ SDR on Medium Wave & Long Wave

In my recent post on the AirSpy HF+ vs Elad FDM-S2, I commented on medium wave reception only.

This past weekend I swapped out the Wellbrook ALA1530S+ for another Wellbrook loop, the ALA1530LN Pro. This LN Pro model is less likely to overload receivers at my suburban Tacoma, WA location. Both AirSpy and Elad radios performed admirably with the LN Pro and it was nearly impossible to find any reception differences on medium wave.

Before the antenna swap though I experimented with inline attenuation modules (“bullets”), typically used in cable TV installations. I used the same sample rates on the SDRs as described in the previous article. After some tests with different attenuation levels, I came to the following conclusions during daytime comparisons:

FDM-S2 with ALA1530S+ loop, medium wave: needs a minimum of 6 dB attenuation to avoid overloading. Anything less causes saturation of the spectrum & waterfall, “crunching” overload noises, and minimal or no received signal.

HF+ with ALA1530S+ loop, medium wave: I had to search diligently to find any signs of false signals or overloading, but finally noticed a weak image or spur of a S-9+60 dB (-13.5 dBm) local station on 1560 that was appearing very weakly on 1270 kHz, mixing with the station on that frequency. Sometimes it was there, other times the spur or image would drop down and disappear, leaving the 1270 signal alone. If I added just 3 dB of attenuation in the antenna’s feed line, the interference from the 1560 station was gone for good. The S-9+60 dB station is a very strong signal; it’s impressive that the AirSpy HF+ deals with this and similar powerhouse signals so well.

Long wave: Below are two screen captures from my local long wave reception in the evening, made moments apart with each receiver.

FDM-S2

HF+

As you can tell, there are a half dozen or so additional signals seen on the HF+ below 200 kHz that do not appear on the FDM-S2. These extra spikes are images or spurs from medium wave signals that were missing from the FDM-S2’s reception–bravo Elad! However, the remaining spikes on both radios below 200 kHz seemed to be noise or interference.

Each receiver had roughly equal performance in the bulk of the long wave spectrum, when I did A-B comparisons on the same beacon signals. I’m not a LW or NDB DXer however, so I can’t claim any expertise on these frequencies. In short, though, both radios seem neck-and-neck from about 200 to 500 kHz.

The DXer of LW frequencies may want to look elsewhere for a better performing radio than either the FDM-S2 or HF+. SWLing Post reader Tudor Vedeanu has commented that the SDRPlay RSP1A  and the Eton E1 work very well at long wave.

Guy Atkins is a Sr. Graphic Designer for T-Mobile and lives near Seattle, Washington.  He’s a regular contributor to the SWLing Post.

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Now’s the time to grab longwave DX!

If you’ve been wanting to log France Inter as longwave DX, you’re running out of time. France Inter is shutting down their 162 kHz longwave service on December 31, 2016.

I’m grateful to SWLing Post contributor, Ron, who has persistently reminded me that these are some of the last days to catch France Inter as LW DX here in North America.  Indeed, he shared a bit of interesting and encouraging news a couple weeks ago:

On the Radiodiscussions DX forum, Jim Farmer over in San Antonio got and recorded France Inter on 162 khz using a PK loop and Sony 7600GR.

The PK Loop he’s referring to is this one and, of course, the Sony ICF-SW7600GR is one of my staple portables.

While I’d love to try to grab France Inter with my Sony, my schedule makes it very difficult to arrange. Fortunately, I have SDRs which allow me to record spectrum throughout the night, then review the recordings in the morning.

Throughout the month of December, I’ve been recording a small chunk of longwave spectrum–with my WinRadio Excalibur–during the night and reviewing it in the morning in hopes that I could grab an opening from France Inter.

I was rewarded on December 19, 2016 around 0300 UTC. Though there was atmospheric noise that night in the form of static crashes, I snagged France Inter on 162 kHz.

My spectrum display from the Excalibur.

The 162 kHz carrier was barely above the noise floor (see above), so it was certainly weak signal DX. Here’s an audio sample:

Click here to download the mp3 file.

When that short LW opening happened, I was also able to snag Medi 1 from Morocco on 171 kHz. Again, not fantastic copy, but I’m happy:

Click here to download the mp3.

Mind you, both France Inter and Medi 1 only transmit at 2,000 watts–that’s flea power compared to our shortwave broadcasters. It’s amazing those signals can even hop the Atlantic.

Correction…an SWLing Post reader, qwerty.am, comments:

Actually, the power of France Inter and Medi1 is 2000 kW and 1600 kW respectively. So the power of most SW broadcasters should be called a “flea power” in comparison to what is used on longwave. The smallest output on LW band in Europe is 50 kW, it’s used by Denmark and Czech Rep. The 162 kHz transmitter is closing on Dec 26th, according to the latest news.

Wow!

Again, if you’d like to grab  longwave stations before they disappear, now is the time! Our LW broadcasters are disappearing rapidly. Fortunately, winter (here in the northern hemisphere) is the best time to chase LW DX.

Thanks, again, Ron for your encouragement! I’ll keep listening and recording!

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Help identifying longwave transmitters

SX-99-Dial-Nar

As many of you know, I’ve been catching up on correspondence recently as the past few weeks have been quite hectic. 

SWLing Post reader, Andy (G0FTD), sent the following message several weeks ago, but is still seeking help:

I came across your website recently, so good to read something dealing with proper SWLing!

Last night I set up an experiment on 279Khz.

This is because of my interest in something called QRSS beacons in  amateur radio. I use the HF bands, but recently became interested in the LF  bands, 136 / 475Khz amateur bands and propagation.

I thought it would be interesting to test for the times that the day / nightime occurs at LF.

To do this I decided to use 279Khz, which by rights only has 2 transmitters on them, and at a convenient distance.

The only list I have says that Belarus and Turkey operate transmitters, so in theory I should only see 2 traces on my Argo software.

UNID 279KHZ

But I was surprised to see 3 traces.

Two of them have about a 1Hz offset to the main one, exactly on 279Khz.

I wonder if your readers can confirm the transmitters ?

Maybe Belarus is operating two TX sites with the offset, and the other is Turkey ?

You can see that the two offset ones go QRT at the same time.

If you can help Andy, please comment. Again, Andy, apologies for the delay in posting your inquiry!

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