Category Archives: Mediumwave

SDR#’s Co-Channel Canceller Gets Additional Options

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In my earlier article, I introduced the Co-Channel Canceller, a unique feature in AirSpy’s SDR# program for the benefit of medium wave DXers.

Now only a day later, software author and AirSpy founder Youssef Touil expands the toolset of Co-Channel Canceller with I.F. Offset and Channel Bandwidth controls.

To download this latest release, click here to go to AirSpy’s downloads page.

It’s my hope that AirSpy will publish a tutorial or YouTube video(s) with step-by-step examples to help with using this unique feature. Until then, it’s certainly fun to try!

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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AirSpy SDR#’s New Killer Feature: the Co-Channel Canceller

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An example of an AirSpy SDR# software screen.

A version of AirSpy’s popular SDR# software, showing the dark mode interface introduced in 2019. SDR# is always evolving, and the latest new tool is the Co-Channel Canceller.

It’s easy to take for granted the magical math that happens in Software Defined Radio. Occasionally though a breakthrough occurs which really grabs our attention, thanks to the hard work and bright minds of the designers behind the receivers and the software.

On the software side, the first series of “wow” moments happened for me in 2007-2008 when Nico Palermo of Perseus SDR fame expanded the program’s alias-free bandwidth incrementally from a modest (but impressive for the time) 100 kHz all the way up to the current 1600 kHz coverage.

The top-end 1600 kHz bandwidth was a game changer which allowed  medium wave DXers the opportunity to record IQ-WAV files of the entire band for later review, analysis, and DXing. It’s even more impressive considering this expansion was done without any additional hardware or receiver updates.

What did Nico charge Perseus owners for this incredibly useful expansion of spectrum and waterfall bandwidth? Nothing! The program with its much improved features continued freely available to previous and new Perseus SDR owners.

Now in 2020, Youssef Touil, AirSpy’s hardware and software developer, brings  a “killer feature” to his own SDR program named SDR#, for the benefit of medium wave DXers: the Co-Channel Canceller. The cost for this innovative tool? Yep, it’s a free addition to SDR#.

What are the benefits of the Co-Channel Canceller? This question is best answered by listening to three examples published by Youssef on his Twitter feed.

Read the descriptions below and listen to the brief audio files. In each example the Co-Channel Canceller is turned on and off a few times:

For the first example above, I suspect the 594 kHz station is Saudi Arabia’s Radio Riyadh, and the off-channel 596 kHz signal is Al Idaa Al-Watania from Morocco. It’s impressive that the 50 kw 596 station can be uncovered to any degree, as Radio Riyadh is a whopping 2000 kw!

In the AirSpy Groups.io forum, Youssef clearly illustrates the steps needed to initiate the Co-Channel Canceller. I’ve reproduced his screenshots below:

I’ve only just begun to explore the possibilities of the Co-Channel Canceller tool, but it holds promise of helping to reveal and identify hopelessly buried co-channel or adjacent channel stations. Not only does it work “live” in real time reception, it functions well with recorded IQ-WAV files too! Checkout the newest version of SDR# and give this new feature a try. I can imagine situations where this tool could be highly useful at times for the shortwave DXer also.

Thanks, Youssef, for this brilliant tool, which you’ve included free with the newest SDR# !

I encourage radio hobbyists to support AirSpy’s efforts to advance the state-of-the-art. The diminutive AirSpy HF+ Discovery receiver is not only a reasonably priced SDR to use with SDR#, it’s a top performer and a recipient of the World Radio TV Handbook’s Best Value SDR award for 2020.

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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More field time with the new Icom IC-705 general coverage QRP transceiver

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I’ve been using the Icom IC-705 pretty heavily since I took delivery of it a couple weeks ago.

The more time I spend with this radio, the more I like it.

Serious functionality and features

I originally stated that I’d probably sell the IC-705 after my review/evaluation period because it simply doesn’t have the design characteristics I like in a field QRP radio.

I tend to prefer simple field radios with a basic high-contrast LCD or analog display, and a protective cover over the display. I’m not personally the biggest fan of pressure sensitive touch screens in field applications.

Earlier this week, I stopped by Lake Norman State Park for a quick Parks On The Air (POTA) activation.

I wrote a field report on QRPer.com noting the fact that the IC-705 is a superb SSB transceiver. It truly is. I included a video showing the IC-705 as I worked a few stations on the 40 meter band, and another video demonstrating SSB memory keying (politely overlook the fact I had the rig set to LSB on 20 meters in that video–!).

Listening in

When I finish a park activation, I often spend a little time on the broadcast bands tuning around and enjoying the low-RFI setting.

At Lake Norman, I decided to make a short video highlighting the wide receiving range of the IC-705. The video only highlights a few bands–the IC-705 can actually receive from 0.030–199.999 MHz and 400.000–470.000 MHz.

The EFT-MTR end-fed antenna I had connected to the IC-705 that day was not ideal for reception above 15 MHz, but as you’ll see, it was adequate for a little radio fun. I was using the Emtech ZM-2 external antenna tuner that day because my mAT-705’s battery died.  I highly recommend the ZM-2 for shortwave listeners and QRPers alike because it makes it so easy to tweak wire antennas for optimal matching and reception. In the video, however, I left the tuner in the last matched configuration. This isn’t exactly a pro video, but I hope you’ll enjoy it anyway:

The Icom IC-705: A keeper

This transceiver is so versatile, I don’t think I can let go of it. I really appreciate the IC-705’s frequency versatility and excellent performance. With this compact rig, I can do some proper SWL DXing and possibly even FM and MW DXing.

As simple as it is, the built-in digital recorder clinches the deal.

The IC-705 is a pricey piece of kit at $1300 US, but I suspect Icom will lower the price or start offering rebates once the supply/demand curves normalize. At present, retailers are struggling to keep up with customer demand and most purchases are on back-order.

Blind Audio Test results

I’ve just closed the surveys for our IC-705 blind audio tests. The response was overwhelming and the results?  Well, you’ll soon find out. I hope to present all of the findings in a post within the next few days.

Boomark this link to follow all of our IC-705 posts.

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Tecsun PL-990 Hidden Feature: Toggling ferrite bar and telescopic whip antenna on MW & LW bands

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Many thanks to Anna at Anon-Co who recently shared an interesting “hidden feature” of the Tecsun PL-990 which allows the user to toggle between the internal ferrite antenna and telescoping whip antenna while on either the mediumwave or logwave bands.

Procedure:

1) Turn on the radio and then select either the MW or LW frequency band.

2) Press and hold the [ 3 ] key for about 2 seconds.

When the display shows “CH-5” (actually an “S” which stands for shortwave telescopic antenna) the radio is now set to MW/LW reception using the telescopic whip antenna.

The display will show MW (or LW) and SW on the left side of the screen.

3) Press and hold the [ 3 ] key for about 2 seconds.

When the display shows “CH-A” (“A” stands for “AM”) the radio is now set to MW/LW reception using the internal ferrite antenna once again.

The display will also show only MW (or LW) on the left side of the screen.

Pressing and holding the [ 3] key essentially toggles between these two antenna settings.

I’ve actually found that, indoors, using the whip antenna on mediumwave has been more effective at mitigating RFI with strong local stations. The ferrite bar antenna has more gain, of course, but for locals it’s not necessarily needed.

Many thanks, Anna, for sharing this tip!

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Gary DeBock experiments with FSL antenna nulling to eliminate a “pest” station

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Many thanks to SWLing Post contributor and Ultralight DX enthusiast, Gary DeBock, for sharing the following guest post:

Nulling a local pest with dual FSL Loops

by Gary DeBock

After many dual FSL antenna experiments I’ve finally determined how to effectively cancel out QRM from a local pest that is off to the side (ideally 90 degrees different, but practical from 50 degrees to 90 degrees different) from a weak DX station, although I’m not quite sure of the theory behind this discovery.

This experiment was an attempt to cancel out QRM from a local pest, 950-KJR in Seattle, WA (35 miles/ 56 km to the north) and chase 950-KKSE in Parker, CO (1005 miles/ 1617 km to the southeast) during the early morning hours. The receiver was a basic (non-SSB) C.Crane Skywave, and two identical 5 inch ferrite rod FSL antennas were used. Please refer to the photo (above) to follow this description.

Step 1) Null out the pest station with the portable radio’s loopstick (away from the FSL antennas). Set the radio down in this nulled position, so that the pest station is as weak as possible, while ensuring that there is space to set up the FSL antennas to the back and side (see photo).

Step 2) Take the “Reception FSL” and use it to peak the pest station’s frequency, setting it up parallel to the portable radio as shown, at the position providing the maximum inductive coupling gain. This will temporarily boost up the pest station, which previously was nulled.

Step 3) Take the “Nulling FSL” and pretune the frequency to that of the pest station. You can do this either by adjusting the variable cap plates to match those of the “Reception FSL,” or by temporarily peaking the pest station’s signal in a position in front of the portable radio. After setting this frequency, set the “Nulling FSL” off to the side of the portable radio as shown, with the spacing identical to the spacing between the radio and the “Reception FSL.”

Step 4) Slowly and carefully tune the “Nulling FSL” until you hear the pest station’s signal take a sharp drop. This setting will be very sharp, but once you find this position you will have nulled out the pest very effectively, and if another station is on the frequency, it may suddenly become dominant, even if it is far away (like 950-KKSE in Denver).

Some MP3’s from this morning’s experiments:

950-KJR in nulled position with the portable only

950-KKSE generally dominant over the local pest KJR when the “Nulling FSL” is peaked

Fascinating, Gary! I don’t understand the dynamics of why this works, but it’s amazing that it does so effectively. I can think of two MW frequencies in particular where I could put a system like this to the test. 

Thank you for sharing!

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QTC Article: Clear Channel MW Broadcast Stations in Australia

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Many thanks to SWLing Post contributor, Kris Partridge, who notes that the July/August 2020 issue of the Australian amateur radio magazine QTC (an issue we noted in a previous post is free) actually has an article about the mediumwave scene in Australia.

Click here to download a PDF of those pages only from the magazine, or better yet, grab the full issue from our previous post.

Thanks for pointing out this article, Kris. I really enjoyed reading this issue of QTC. Great to see a ham radio publication that covers more than *just* ham radio!

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Bruce compares two homebrew NCPL antennas to the Airspy Youloop

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The Airspy Youloop

Many thanks to SWLing Post contributor, Bruce (VE3EAR), who writes:

I decided that more testing of the Noise-Cancelling Passive Loop (YouLoop) antenna was needed, but I wanted to start with a clean page.

I built two identical loops using some 3/8 inch heliax scraps I had on hand. Both are one metre in diameter and employ the same feed arrangement, with a balun wound on a half inch square binocular core of type 75 mix. There are four turns on the antenna side and eight on the feed line side, of #24 gauge plastic insulated wire. The feed line shield connects to the antenna shields. The only difference between the two antennas is at the top of the loop, opposite to the feed point. One has a simple one inch gap in the shield, with the centre conductor passing across the gap, while the second one uses the crossover connection of the YouLoop design.

I’ve been running some A-B comparison listening sessions, both mid-day and in the evenings after local sunset. The testing is done outside, with the antennas hanging on a low limb of a maple tree in front of the house. The feed line is about twenty feet of coax which connects to my Realistic DX-440 receiver on the front porch. Testing is done listening to the AM broadcast band and the 160, 80, and 40 metre ham bands, with the loop aligned both E-W and N-S and about one loop diameter off the ground.

Both loops work well, but I do have to give the nod to the YouLoop (by Airspy), which produces a stronger signal of two S-units higher than the conventional loop. It also has deeper and sharper nulls, which can sometimes produce total nulling of the station!

73, Bruce, VE3EAR

Thank you so much, Bruce, for sharing your findings with us! I, too, have found that the Youloop generally outperforms my homebrew NCPL antenna. I believe one of the reasons for this as Youssef at Airspy once told me is because the Youloop has a lower loss transformer than anything that can be wound by humans (0.28 dB)–this improves gain.

Click here to read our review of the Youloop and click here for step-by-step instructions on building your own Noise-Cancelling Passive Loop antenna.

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