Category Archives: Mediumwave

Ham Radio Workbench episode explores Diversity Reception

The SDRplay RSPduo

I just finished listening to the most recent episode of the Ham Radio Workbench with John Fallows (VE6EY) as a guest.

John is an SWL and Ham Radio operator and speaks at length about how he uses diversity reception to mitigate persistent local RFI (radio frequency interference).

If you have persistent issues with radio interference or if you’ve been curious about using diversity reception for mediumwave and shortwave DXing, I highly recommend listening to this episode. John has been known to frequent the SWLing Post and actually comes into the discussion primarily from an SWL’s perspective.

If you’ve tried diversity reception or a noise-cancelling system like the Timewave ANC-4+ in the past with mixed results, you’ll definitely benefit from listening to John’s best practices.

In addition, John points out that the excellent SDRplay RSPduo is a very affordable way to explore proper diversity reception.

How effectively can you mitigate RFI with diversity reception? Check out this video on YouTube queued up to the point where John does a live demo with his Anan SDR and loop antennas: https://youtu.be/vu8D87aVUTQ?t=2011 (I also recommend watching to full video presentation for even more detail.)

I’ve embedded the audio for the Ham Radio Workbench podcast below, but you can also find it along with show notes on the Ham Radio Workbench website.

Ham Radio Workbench is one of my favorite podcasts; if you like exploring a wide variety of technical topics, I highly recommend checking it out. It’s available on all podcasting platforms.

Also, check out John VE6EY’s YouTube channel and web site/blog.

Gary DeBock’s XHDATA D-808 loopstick model

6 Replies

Many thanks to SWLing Post contributor, Gary DeBock, who shares the following:

The 7.5 inch (19cm) loopstick XHDATA D-808 model was designed to be the ultimate AM-DXing (or Longwave DXing) travel portable, and can be built for a construction cost of around $30 US. It has already been used by numerous DXers to track down transcontinental and transoceanic AM-DX during overseas travel, and the orange plastic loopstick frame allows full operation of the whip antenna for FM and Shortwave reception.

The modification procedure isn’t difficult, and the full construction article is posted at

https://dreamcrafts.app.box.com/s/5d0pi85jfptgmrj4pd0jsmaybgb6gteh

A video demonstration of its daytime DX performance (compared to the stock model) has been posted on YouTube:

Build one, and join the fun! 🙂

Many thanks for sharing this, Gary! Your ultralight DXing creations are simply amazing!

Guest Post: A synchronous detector crash course!

26 Replies

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 →

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

11 Replies

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 →

Giuseppe’s Homebrew “TFerrite 2” Mediumwave & Shortwave Antenna

5 Replies

Many thanks to SWLing Post contributor, Giuseppe Morlè (IZ0GZW), who shares the following:

Dear Thomas my friend,

I built another Tferrite, (TFERRITE 2), for medium waves–this time also with the shortwave option.

A single variable capacitor, 800 pf, and a primary winding on the 2 ferrites of about 46 turns, a secondary winding of 3 turns to pick up the signal and send it to the receiver.

On the PVC tube I wound 4 more coils, for the shortwaves, connecting the ends to the same variable together with the other ends.

I interposed a switch on one end to eliminate or insert shortwaves.

I am sending you these 3 links from my YT channel where you can see the tests I have done in these days with no propagation.

The yield in mediumwave is excellent, like the other one, yet also good for the shortwaves–to be so small it compares very well.

Let me know what you and the whole SWLing community think!

Thanks to you and a greeting from Italy, Formia on the Tyrrhenian Sea.
73. Giuseppe.

Videos

View on YouTube.

This is brilliant, Giuseppe! Thank you so much for sharing your homebrew antenna projects. It seems they work so well from your beautiful urban location in Italy!

Guest Post: Mediumwave DXing in Botswana

6 Replies

Many thanks to SWLing Post contributor, Peter Wilson, who shares the following guest post and recordings from his listening post in Botswana:

Peter’s receiver is a Airspy HF+ Discovery SDR using SDR Console V3

MWDX from Australia and the USA received in Botswana

by Peter Wilson

Hello Thomas.

I moved my 16.2 metre random wire slightly farther away from the house, and installed a binocular balun and connected 20m of RG58 at the far end, not the “house end”.

Peter’s random wire antenna with binocular balun

Reception examples:

1500 USA WFED Washington DC 12790km

1152 AUS 6PB
ABC NewsRadio Busselton 8469km with ABC News ID

1600 B Radio Nove de Julho ID 7234km
Sao Paulo. Brazil. ID,
Web Address and jingle. Rinsed and repeated.
Portuguese: Radio Nove de Julho [English: Radio 9th July]

1026 kHz MOZ Emissor Provincial de Manica Chimoio 1057km.
A bit parochial but features the radio Mozambique song.

850 USA WTAR Norfolk, Virginia Fox Sports Radio ID 12700km

1296 6RN ABC Radio National. Wagin, Australia 10kW 8644km

558 AUS 6WA ABC Great Southern WA Wagin 8644km

Impressive reception from your home in Botswana! Thank you so much for sharing these recordings, Peter. You’ve certainly made the most of your random wire antenna!

Paul’s thoughts about Mediumwave DXing in Alaska

5 Replies

Many thanks to SWLing Post contributor, Paul Walker, who has kindly allowed me to published some notes he recently shared among MW DXers about DXing in McGrath, Alaska, USA:
During a Zoom hang out with a bunch of Pacific NW DXers, one of the things that come up was why my DXing in Alaska is beyond amazing, and we’ve come to a few conclusions.

The extended darkness. Sunrise in the middle of winter here is 3+ hours later than the west coast, so once their Skywave burns off, I’m left with darkness over the pole and to my west.

There’re no operating AM stations within just under 200 miles from me which is a big help. I have heard distant signals on the same channel as “semi locals” such as 780 and 1080.
And I’m pretty sure there’s something to the fact I’m close to the North Pole. Still far, but closer than most.

Interesting to note though: pre sunset DX isn’t a thing there. What I’ve unscientifically discovered is it seems to be that the entire Pacific has to be dark for DX to be worthwhile for me in the evening … despite my evening DX being Canada and the lower 48 US States.
What most everyone else hears at night, such as the transpacific signals from Japan, China, Australia etc…, I hear in the morning. Hearing anything from Asia or the Pacific at night is EXTREMELY rare.

[Since I’m DXing outdoors in extremely cold conditions] I’m getting extra batteries, extra audio cables (to go between the recorder and the radio), another radio, and another recorder. Oh and some hot hands hand warmers. Also have some extra gloves and hats ordered too.. getting prepped for winter DXing well ahead of time!

The hand warmers are as much for my gloves as they are for my digital recorder… AA batteries don’t last long during continuous use in extreme cold.

i also have a portable battery and extra cable so I can use it for my phone. Those lithium ion batteries hate cold even more than aa alkaline batteries–they will shut off in the cold. In fact, you have to not only warm it up but charge it. The cold causes it to think tis dead…. and even warming it up won’t work.

Here’s a video link to my FSL antenna designed and built by Gary DeBock:

DXIng is one of the reasons I moved back up here to Alaska and it’s entirely fascinating. I learn something new every “DX season”.

Lower 48 theory and ideas just don’t hold a bunch of weight up here … I’ve had ideas and suggestions from some really smart people that just didn’t work out.

Until you’ve DXed in Alaska, it’s hard to explain and understand.

Thank you for sharing your notes, Paul! Having never done DX in those latitudes, I can only imagine how different conditions might be–especially in those long, dark winters!