Category Archives: Travel

Assembling a new compact field radio kit in the Red Oxx Booty Boss

The Red Oxx Booty boss sporting my add-on reflective yellow monkey fist zipper pulls

If you’ve been reading the SWLing Post for long, you’ll have already sorted out that I’m both a radio geek and a pack geek.

The LnR Precision MTR-3B transceiver

I recently purchased an LnR Precision MTR-3B QRP transceiver. I added it to my collection because the rig is so incredibly compact, it gives me the opportunity to keep a full HF radio kit in my EDC bag or packed away for one bag travels.

Now I’m building a full field kit for the MTR-3B in a Red Oxx Booty Boss pack I recently purchased specifically for this radio.

If you’re wondering why I’d build yet another field kit for the MTR-3B instead of simply using field supplies I already have, allow me to explain…

Field radio kit Golden Rule: Never borrow from one kit to feed another

I never violate this rule.  (Well, not anymore, at least.)

I don’t care if I’m building a kit around a portable shortwave receiver, an SDR, or a ham radio transceiver–my radio kits are completely self-contained and organized.

I’m actually plotting a whole series of posts about building portable radio kits and packs because I enjoy the process so much, but for now, I’ll keep my explanation short:

Because I have an active family life and can’t often prepare in advance for field radio time, my kits must be at-the-ready all the time. If we decide (as we are this morning) that we’re heading to a national park for a little hiking and a picnic, I know that when I grab my KX2 field kit, for example, I’ll have everything I need to do a Parks On The Air or Summits On The Air activation. I know my kit contains an antenna, all antenna accessories and hanging supplies, feed line, a fully-charged battery, microphone and/or CW (Morse Code) key/paddles, earphones/speaker, and a transceiver. It’ll also have the little bits we often forget like a pen, notepad, extra connectors/adapters, and even a few first aid supplies.

If you borrow from one radio kit to feed another, you’ll regret it later. I promise.

Case in point

The lab599 Discovery TX500

Here at SWLing Post HQ, I review lots of radios and have a special affinity for field radios. Many times, I either obtain a radio as a loaner from the manufacturer (like the lab599 TX-500), or I purchase a radio with the intention of selling it after the review (as I will with the Xiegu G90). In either case, I don’t want to build a specific field kit for that radio because it’s really only visiting SWLing Post HQ.

The Xiegu G90

When I first took the Xiegu G90 to the field, I felt confident I could simply throw together a quick field kit in one of my smaller backpacks. As I prepared for an impromptu POTA park activation, I discovered that I needed a coax feed line for the kit and the quick solution was to grab the one from my Elecraft KX2 field kit. Even though I knew that would be violating my Golden Rule–a rule I had adhered to for five years and counting–I did it because I was very pressed for time.  That activation went off without a hitch–a total success.

Fast-forward two days later and I had another opportunity to do a park activation, but this time I wanted to use my Elecraft KX2 because I knew I would need to hike into the site and I’d also have to both log and hold the transceiver on my clipboard while sitting on my folding stool. The KX2 is ideal for this as it’s compact and has top-mounted controls.

I hiked into DuPont forest, found an ideal site to play radio, starting deploying the antenna and quickly realized I forgot to put the feed line back in the KX2 kit. Doh! Without even a short piece of coax, I had no way to connect my KX2 to the antenna.

Fortunately, I happened to have a spare coax line back in the car and I also keep two extra BNC adapters in the KX2 kit. Still, I kicked myself as I hiked all the way back to the car. Had I only followed the Golden Rule that had served me so well!

In the end, it could have been worse. I still got to do my activation and hadn’t wasted a 2.5 hour round trip to the park.

You’d better believe the first thing I did when I got back home was to put the coax back in my KX2 field kit and my radio world order had been restored again.

Back to the pack!

I picked the Red Oxx Booty Boss for the MTR-3B because 1.) it’s an ideal size for a super-compact field kit, 2.) it can be carried a number of ways (on back, sling, and over shoulder), 3.) with straps detached, it’s compact & easily fits in my EDC pack and 4.) I love Red Oxx gear and love supporting the company. When you buy a Red Oxx bag, you know it’ll outlast you…not the other way around.

I also ordered reflective monkey fist zipper pulls to replace the stock zipper pulls so that the pack would be easy to spot, for example, on a forest floor at twilight.

Here’s what I’m putting in the Booty Boss:

Here’s the amazing thing: without realizing it, everything in this kit save my earphones was designed and manufactured in the USA. The Booty Boss was made in Montana, the MTR-3B in North Carolina, the Vibroplex antenna in Tennessee, the ABR cable in Texas, the Bioenno battery pack in California. My 20 year old Sennheiser earphones were made in Germany.

I think that’s pretty darn cool and certainly bucks the trend!

Within a week, my battery and cable should arrive and the MTR-3B field kit will be ready for adventure.

I can’t wait!


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Proper Radio Prepping: Keep a kit that is always ready to hit the field!

My Red Oxx Micro Manager packed with a full radio field kit

Yesterday, my family packed a picnic lunch and took a drive through Madison County, North Carolina. It was an impromptu trip. Weather was forecast to be pretty miserable that afternoon, but we took the risk because we all wanted to get out of the house for a bit.

Although that morning I had no intention of performing a Parks On The Air (POTA) activation, my family was supportive of fitting in a little radio-activity, so I jumped on the opportunity!

A quick glance at the POTA map and I determined that the Sandy Mush State Game Land (K-6949) was on our travel route. Better yet, the timing worked out to be ideal for a lunch picnic and before most of the rain would move into the area.

Ready for radio adventure

I had no time to prepare, but that didn’t matter because I always have a radio kit packed, fully-charged, and ready for the field.

My Red Oxx Micro Manager EDC pack (mine is an early version without pleated side pockets) holds an Elecraft KX2 field and antenna kit with room to spare (see photo at top of page).

The Micro Manager pack easily accommodates the entire kit

This 20 year old blue stuff sack is dedicated to antenna-hanging. It holds a reel of fishing line and a weight that I use to hang my end-fed antenna in a tree or on my Jackite telescoping fiberglass pole. The sack also accommodates a 10′ coax cable.

The Elecraft KX2 transceiver, EFT Trail-Friendly Antenna, hand mic, CW paddles, C.Crane earphones, and wide variety of connectors and cables all fit in this padded Lowe Pro pack:

The advantage to having a simple, organized radio kit at the ready is that everything inside has its own dedicated space, so there’s no digging or hunting for items when I’m ready to set up and get on the air.

This level of organization also makes it easy to visually inspect the kit–missing items stand out.

Yesterday I parked our car at one of the Sandy Mush Game Land parking areas, deployed my field antenna, and was on the air in a matter of seven minutes at the most.

Hunter Parking Area Sign

Technically, this should read “Activator” parking area! (A questionable inside joke for POTA folks!)

We planned for heavy rain showers, so I fed the antenna line through the back of my car so that I could operate from the passenger seat up front.

I also brought my Heil Proset – K2 Boom Headset which not only produces better transmitted audio than the KX2 hand mic, but it frees up my hands to log stations with ease. This is especially important when operating in the front seat of a car!

The great thing about the KX2 is that it’s so compact, it can sit on my clipboard as I operate the radio (although typically I have an elastic strap securing it better). Since all of the KX2 controls are top-mounted, it makes operation a breeze even in winter weather while wearing gloves.

Since I routinely use the KX2 for shortwave radio broadcast listening as well, I know I always have a radio “locked and loaded” and ready to hit the air. My 40/20/10 meter band end-fed antenna works well for the broadcast bands, as long as there is no strong local radio interference (RFI). When I’m faced with noisy conditions, I pack a mag loop antenna as well.

What’s in your radio go-kit?

Having a radio kit stocked and ready to go on a moment’s notice gives me a great sense of security, and not just for recreational ham and shortwave radio listening reasons.

Sometimes I travel in remote areas by car where I’m more than an hour away from the nearest town and where there is no mobile phone coverage.

If my car breaks down, I know I can always deploy my radio kit and get help from the ham radio community in a pinch. Herein lies the power of HF radio!

If you haven’t built a radio go-kit, I’d highly recommend doing so. Although I’m a bit of a pack geek, keep in mind that you don’t need to purchase special packs or bags for the job. Use what you already have first.

I’m plotting a detailed post about the anatomy of an HF radio field kit. In the meantime, I’m very curious how many of you in the SWLing Post community also have a radio kit at the ready–one based on a transceiver or receiver.  Please comment!

Better yet, feel free to send me details and photos about your kit and I’ll share them here on the Post!


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The AirSpy HF+ Discovery and a new era of portable SDR DXing

The following article first appeared in the January 2020 issue of The Spectrum Monitor magazine.


The AirSpy HF+ Discovery and a new era of portable DXing

I admit it: I used to be a bit of an old-fashioned radio curmudgeon. One of those, “I like my radios with knobs and buttons” likely followed by, “…and no other way!”

However, about fifteen years ago, many of my DXing friends started turning to the world of software defined radios (or in common parlance, “SDRs”). I staunchly opposed ever following in their footsteps. One of the reasons I for this––a good one––is that, since I spend the bulk of my day in front of a computer, why would I ever want to use a computer when I’m playing radio?

But then…gradually, I found myself playing around with a few SDRs. And I quickly learned that third-generation SDRs were capable of doing something very impressive (and fun), indeed:  making spectrum recordings.  Using this tool, I found I could record not only the audio of one individual signal, but the audio of entire swathes of radio spectrum.  And even more impressive, I learned that you could later load or “play back” the spectrum recording and tune through the bands as if in real time. Any time you want. Before long, I was hooked: SDRs had become my portal into radio time travel!

I quickly found that I loved many of the other advantages of using an SDR, as well, including visual ones––like the ability to view spectrum. The interactive interface allows one to actually see radio signals across the band in real time. I also found incredible value in waterfall displays, which show signals changing in amplitude and frequency over time. Cool stuff.

I purchased my first dedicated SDR in 2012, a WinRadio Excalibur. It was––and still is––a benchmark receiver, performing circles around my tabletop receivers and general coverage transceivers.

And today, although I own and love a number of legacy radios and still listen to them in the good old-fashioned manner to which I became accustomed, I find I’m now spending the bulk of my time DXing with SDRs.

And then, more recently, two amazing things happened in the world of SDRs. Strong market competition, together with serious innovations, have come into play. Thus, for less than $200 US, you can now purchase an SDR that would have easily cost $1,000 US only ten years ago. And now, in many cases, the $200 SDR of today will outperform the $1,000 SDR of yesteryear. We are, indeed, living in good times.

And now––no more a radio curmudgeon––I’m comfortable with my SDR-user status and time at the computer, and glad I was just curious enough about SDRs to let them into my radio (and computer) world.

Portable SDRs

Since I initially dived into the world of SDRs, I’ve tried to think of a way to take them into the field.

But first, let’s get an obvious question out of the way:

Why would you want to drag an SDR into the field, when a traditional battery-powered radio is so much easier to manage?

After all, you may say, portable and even mobile tabletop receivers require no computer, no hard drive, and are likely more reliable because there are less components to manage or to cause problems for you.

In answer, let’s look at a few scenarios where heading to the field with an SDR system might just make sense.  (Hint: Many of these reasons are rooted in the SDR’s ability to record spectrum).

Good Reason #1:  Your home location is not ideal for playing radio.

Photo by Henry Be

My good friend, London Shortwave, lives in the middle of London, England. He’s an avid radio enthusiast and DXer, but his apartment is almost a perfect storm of radio interference. Listening from his home is challenging, to say the least: he can only use indoor antennas and RFI/QRM simply inundated his local airwaves.

Many years ago, he discovered that the best way to DX was to go to an area that put urban noise and radio interference at a distance.  He found that by visiting large local parks, he could play radio with almost no RFI.

Being a computer guru, he started working on a portable SDR setup so that he could go to a park, set up an antenna, and record radio spectrum while he read a book.  His systems evolved with time, each iteration being more compact less conspicuous that the previous. Later, he could head back home, open the recorded spectrum files, and tune through these “time-shifted” recordings in the comfort of his flat. This allowed London Shortwave to maximize the low-RFI listening experience by reliving the time in the park.

Over the years, he tweaked and adapted his setup, often writing his own code to make small tablets and portable computers purpose-built portable-spectrum-capture devices. If you’re curious, you might like to read about the evolution of his systems on his blog.

Clearly, for London Shortwave, an SDR is the right way to capture spectrum and thus likely the best solution for his DX listening.

Good Reason #2:  Weak-signal workarounds.

Typically radio enthusiasts turn to field operation to work in a lower-noise environment and/or where there are no antenna restrictions, often to log new stations and DX.

SDRs afford the DXer top-shelf tools for digging weak signals out of the muck. SDR applications have advanced tools for tweaking AGC settings, synchronous detectors, filters, noise reduction, and even to tailor audio.

The WinRadio Excalibur application even includes a waterfall display which represents the entire HF band (selectable 30 MHz or 50 MHz in width)

On top of that, being able to see a swath of spectrum and waterfall gives one an easier way––a visual way––to pinpoint weak or intermittent signals. This is much harder to do with a legacy radio.

Case in point:  I like listening to pirate radio stations on shortwave. With a spectrum display, I can see when a new station may be tuning up on the band so can position the receiver to listen in from the beginning of the broadcast, and never miss a beat.

Or, in another example, the visual aspect of spectrum display means I can easily locate trans-Atlantic DX on the mediumwave bands by looking for carrier peaks on the spectrum display outside the standard North American 10 kHz spacing. The signals are very easy to spot.

Good Reason #3: DXpeditions both small and large.

Mark Fahey, scanning the bands with his WinRadio Excalibur/Surface Pro 2 combo at our 2015 PARI DXpedition

Whether you’re joining an organized DXpedition or you’re simply enjoying a little vacation DXpedition, SDRs allow you to make the most of your radio time.

Indeed, most of the organized DXpedition these days heavily incorporate the use of SDRs specifically so DXers can record spectrum. Much like example #1 above, doing this allows you to enjoy the noise-free optimal conditions over and over again through spectrum recordings. Most DXpeditioners will have an SDR making recordings while they use another receiver to DX in real time. Later, they take the recording home and dig even more weak signals out of the mix: ones that might have otherwise gone unnoticed.

Good Reason #4: Sharing the spectrum with like-minded listeners.

Earlier this year, Mark gave me this 8TB hard drive chock-full of spectrum recordings.

One of the joys I’ve discovered  in making field spectrum recordings is sharing them with fellow DXers. Most of the time when I go to shortwave radio gatherings (like the Winter SWL Fest), I take a couple hard drives to exchange with other SDR enthusiasts. My friend, Mark Fahey, and I have exchanged some of our favorite spectrum recordings this way. I give him a hard drive chock-full of terabytes of recordings, and he reciprocates. Back home (or on the train or airplane) I open one of his recordings and, boom! there I am in his shack in Freeman’s Reach, Australia, tuning through Pacific stations that are not easily heard here in North America, maybe even turning up some gems Mark himself may have overlooked…just as he is doing with my recordings from the southeast US.

I’ve also acquired DXpedition spectrum recordings this way. It’s great fun to “be there” through the recordings and to enjoy some of the benefits of being on the DXpedition in times when I couldn’t actually make it there in person. For a DXer with a consuming job, busy family life, or maybe health problems that limit their travel, an SDR recording is the way to go.

Good Reason #5: Family time

Photo by David Straight

I’m a husband and father, and no matter how much I like to play radio when we’re on vacation, my family comes first, and our family activities take priority.

Having a field-portable SDR setup means that I can arrange a “set it and forget it” spectrum capture device. Before we head out the door for a family visit, tour of the area, or a hike, I simply set my SDR to record spectrum, then listen to what I “caught” after I return, or after I’m home from vacation.

This practice has allowed me to enjoy radio as much as I like, without interrupting our family adventures. Can’t beat it!

Past challenges

With all of these benefits, one might wonder why many other DXers  haven’t been using portable SDRs in the field for a while now? That’s a good question.

Power

The WinRadio G31DDC, like many SDRs of the era, has separate data and power ports

In prior years, DXers and listeners might have been reluctant to lug an SDR and its requisite apparatus out with them. After all, it’s only been in the past decade or so that SDRs haven’t required a separate custom power supply; some legacy SDRs either required an odd voltage, or as with my WinRadio Excalibur, have very tight voltage tolerances.

Originally, taking an SDR to the field––especially in places without grid mains power––usually meant you also had to take a pricey pure sine wave inverter as well as a battery with enough capacity to run the SDR for hours on end.

Having spent many months in an off-grid cabin on the east coast of Prince Edward Island, Canada, I can confidently say it’s an ideal spot for DXing: I can erect large wire antennas there, it’s on salt water, and there are literally no locally-generated man-man noises to spoil my fun.  Of course, anytime we go to the cottage, I record spectrum, too, as this is truly a honey of a listening spot.

The view from our off-grid cabin on PEI.

The first year I took an SDR to the cabin, I made a newbie mistake:  it never dawned on me until I arrived and began to put it to use that my Goal Zero portable battery pack didn’t have a pure sine wave inverter; rather, I found it had a modified sine wave inverter built into it. The inverter could easily power my SDR, sure, but it also injected incredibly strong, unavoidable broadband noise into the mix. It rendered my whole setup absolutely useless. I gave up on the SDR on that trip.

Both the Airspy HF+ (top) and FDM-S2 (bottom) use a USB connection for both data transfer and power. Photo by Guy Atkins.

Today, most SDRs actually derive their power from a computer or laptop through a USB cable, one that doubles as a data and power cable. This effectively eliminates the need for a separate power system and inverter.

Of course, your laptop or tablet will need a means of recharging in the field because the attached SDR will drain its battery a little faster. Nowadays it’s possible to find any number of portable power packs/banks and/or DC battery sources to power laptops or tablets, as long as one is cautious that the system doesn’t inject noise. This still requires a little trial and error, but it’s much easier to remedy than having two separate power sources.

Portable computers

Even a Raspberry Pi 3B has enough horsepower to run SDR applications.

An SDR is nothing without a software application to run it. These applications, of course, require some type of computer.

I the past, SDR applications needed some computing horsepower, not necessarily to run the application itself, but to make spectrum recordings.  In addition, they often required extra on-board storage space to make these recordings sufficiently long to be useful.  This almost always meant lugging a full-sized laptop to the field, or else investing in a very pricey tablet with a hefty amount of internal storage to take along.

Today we’re fortunate to have a number of more portable computing devices to run SDR applications in the field: not just laptops or tablets, but mobile phones and even mini computers, like the eminently affordable $46 Raspberry Pi. While you still have to be conscious of your device’s computing horsepower, many small devices are amply equipped to do the job.

Storage

64-128 GB USB flash/thumb drives are affordable, portable storage options.

If you’re making spectrum and audio recordings in the field, you’ll need to store them somehow. Wideband spectrum recordings can use upwards of 2GB of data per minute or two.

Fortunately, even a 64GB USB flash drive can be purchased for as little as $7-10 US. This makes for quick off-loading of spectrum recordings from a device’s internal memory.

My portable SDR setup

It wasn’t until this year that all of the pieces finally came together for me so that I could enjoy a capable (and affordable!) field-portable SDR setup. Two components, in particular, made my setup a reality overnight; here’s what made the difference.

The AirSpy HF+ Discovery

Last year, AirSpy sent me a sample of their new HF+ Discovery SDR to test and evaluate. To be fully transparent, this was at no cost to me.

I set about putting the HF+ Discovery through its paces. Very soon, I reached a conclusion:  the HF+ Discovery is simply one of the best mediumwave and HF SDRs I’ve ever tested. Certainly, it’s the new benchmark for sub-$500 SDRs.

In fact, I was blown away. The diminutive HF+ Discovery even gives some of my other benchmark SDRs a proper run for their money. Performance is DX-grade and uncompromising, sporting impressive dynamic range and superb sensitivity and selectivity. The noise floor is also incredibly low. And I still can’t wrap my mind around the fact that you can purchase this SDR for just $169 US.

The HF+ Discovery compared in size to a DVD

In terms of portability, it’s in a class of its own. It’s tiny and incredibly lightweight. I evaluate and review SDRs all the time, but I’ve never known one that offers this performance in such a tiny package.

Are there any downsides to the HF+ Discovery? The only one I see––and it’s intentional––is that it has a smaller working bandwidth than many other similar SDRs at 768 kHz (although only recently, Airspy announced a firmware update that will increase bandwidth). Keep in mind, however, that the HF+ series SDRs were designed to prevent overload when in the presence of strong local signals. In fairness, that’s a compromise I’ll happily make.

Indeed, the HF+ Discovery maximum bandwidth isn’t a negative in my estimation unless I’m trying to grab the entire mediumwave band, all at once. For shortwave work, it’s fine because it can typically cover an entire broadcast band, allowing me to make useful spectrum recordings.

The HF+ Discovery is so remarkably tiny, that this little SDR, together with a passive loop antenna, can fit in one small travel pouch. Ideal.

The antennas

My homebrew NCPL antenna

Speaking of antennas, one of the primary reasons I’m evaluating the HF+ Discovery is because it has a very high dynamic range and can take advantage of simple antennas, in the form of passive wideband magnetic loop antennas, to achieve serious DX.

AirSpy president and engineer, Youssef Touil, experimented with several passive loop antenna designs and sizes until he found a few combinations ideally matched with the HF+ Discovery.

My good buddy, Vlado (N3CZ) helped me build such an antenna per Youssef’s specifications. Vlado had a length of Wireman Flexi 4XL that was ideal for this project (thanks, Vlad!). The only tricky part was penetrating the shielding and dielectric core at the bottom of the loop, then tapping into both sides of the center conductor for the balun connections.  Being Vlado, he used several lengths of heat shrink tubing to make a nice, clean, snag-free design. I’ll freely admit that, had I constructed this on my own, it wouldn’t have been nearly as elegant!

Click here for a step-by-step guide to building your own NCPL (Noise-Cancelling Passive Loop Antenna.

Youssef also sent me a (then) prototype Youloop passive loop antenna. It’s incredibly compact, made of high quality SMA-fitted coaxial cables. It can be set up in about 30 seconds and coiled to tuck into a jacket pocket.  The AirSpy-built loop has a lower loss transformer than the one in the homemade loop, which translates into a lower noise figure for the system.

Click here to read my review of the Youloop.

Let’s face it: SDR kit simply doesn’t get more portable than this.

The computer

My Microsoft Surface Go tablet on a hotel bed.

In the past, I used an inexpensive, circa 2013 mini Windows laptop with an internal SSD drive.  Everything worked beautifully, save the fact that it was challenging to power in the field and the internal capacity of the hard drive was so small (16GB less the operating system). In addition, it was a few years old, bought used, so the processor speed was quite slow.

This year, on the way back from the Huntsville Hamfest, I stopped by the Unclaimed Baggage Center in Scottsboro, Alabama. This center has a wide variety of used portable electronics at discount prices. I felt pretty lucky when I discovered a like-new condition Microsoft Surface Go tablet and keyboard with original charger for $190. The catch? The only data port on the tablet is a USB-C. But I grabbed a small USB-C to standard USB 3.0 dongle (for $2!) and took a risk that it would work with the HF+ Discovery.

Fortunately, it did! Score!

While the Surface Go is no powerhouse, it’s fast enough to run any of my SDRs and make spectrum recordings up to 2 MHz in width without stuttering. The only noise it seems to inject into the mix is a little RFI when I touch the trackpad on the attached keyboard.

Power

One of my LiFePo batteries

The HF+ Discovery draws power from the Surface Go tablet via the USB port. With no additional power supply, the Surface Go may only power the HF+ Discovery for perhaps an hour at most. Since I like doing fully off-grid operations and needed to avoid RFI from inverters, I needed a portable power solution.

Fortunately, the Surface Go has a dedicated power port, so I immediately ordered a DC power cable with a standard car lighter plug.

At the Huntsville Hamfest I also purchased a small 12V 4.5 Ah Bioenno LiFePo battery and paired it with a compact Powerpole distribution panel kit I purchased in May at the 2019 Dayton Hamvention.

The LiFePo battery is small, lightweight, and can power the tablet /SDR combo for hours on end. Moreover, I have noticed no extra noise injected when the DC power is applied.

My HF+ Discovery-based portable SDR kit

My portable SDR kit on a hotel balcony.

Now I have this kit, I couldn’t be more pleased with it. When all of the components of my SDR system are assembled, they work harmoniously. The entire ensemble is also incredibly compact:  the loop antennas, SDR, Surface Go tablet, battery, and distribution panel all fit in a very small travel pack, perfect for the grab-and-go DX adventure.

The entire kit: SDR, cables, Youloop antenna, connectors and adapters all fit in my Red Oxx Lil’ Roy pack.

In November, I took the kit to the coast of South Carolina and had a blast doing a little mediumwave DXing from our hotel balcony. We were very fortunate in that I had two excellent spots to hang the homemade loop antenna: on the main balcony, and from the mini balcony off the master bedroom. Both spots yielded excellent results.

What impressed me most was the fact that the SDR# spectrum display and waterfall were absolutely chock-full of signals, and there was very little noise, even in the popular resort area where we were staying. I found that my portable radios struggled with some of the RFI emanating from the hotel, but the HF+ Discovery and passive loop combo did a much better job mitigating noise.

Check out the AM broadcast band on the spectrum display.

But no need to take my word for it.  If you would like to experience it first hand, why not download an actual spectrum recording I made using this setup?

All you’ll need to do is:

  1. Download the 1.7 GB (.wav formatted) spectrum file at this address
  2. Download a copy of SDR# if you don’t already have an SDR application that can read AirSpy spectrum files.
  3. Install SDR#, and run it.
  4. At the top left corner of the SDR# screen, choose “IQ File (.wav)” as the source, then point it to where you downloaded the file.
  5. Press the play button, and experience a little radio time travel!

This particular recording was made on the mediumwave band on November 17, 2019, starting at around 01:55 UTC.

My portable SDR kit capturing spectrum during a hike in Pisgah National Forest.

I’ve also taken this setup to several parks and remote outdoor locations, and truly enjoyed the freedom of taking spectrum recordings back home to dig through the signals.

Conclusion

I finally have a portable SDR system that allows me the flexibility to make spectrum recordings while travelling. The whole setup is compact and can easily be taken in a carry-on bag when flying.

The glory of this is, I can tune through my spectrum recordings in real time and DX when I’m back home, or even on the way back home, in the car, train, or airplane. It’s simply brilliant.

If you don’t already own an SDR, I can highly recommend the AirSpy HF+ Discovery if you’re primarily interested in HF and MW DXing. If you need a wideband SDR, I could also recommend the recently released SDRplay RSPdx, although it’s slightly heavier and larger than the AirSpy.

Thankfully, I am now an SDR enthusiast that can operate in the field, and this radio has had a lot to do with it. I’ll be logging many hours and miles with the AirSpy HF+ Discovery: its incredibly compact footprint, combined with its brilliant performance, is truly a winning combo.

Click here to check out the Airspy HF+ Discovery

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A Compact RSPdx & Wellbrook Loop Kit for the Beach — My Approach

I have enjoyed three to four medium wave and shortwave DXpeditions per year since 1988, to sites on the Washington and Oregon coasts. I love the chance they give to experiment with antennas in a (hopefully!) noise-free location, and concentrate on catching stations that might not be heard from home.

All of my DX trips have been via car–until now! I’ve just returned from nine vacation days in Hawaii (Waikoloa Beach, on the Big Island), and I thought others might like to see the radio related items I chose to take along for air travel. I’m pleased to report that everything worked as planned, and I have five days of SDR IQ WAV files of the MW band for review, all recorded in the time frame surrounding local dawn.

My goal was not the smallest, most compact portable setup, but one with high performance and modest size. Fitting everything into a day pack was another requirement. A simple wire antenna and an even smaller Windows tablet or laptop than the one I’ve used (and a smaller SDR like the HF+ Discovery, for that matter) would make a much smaller package. However, the items I’ve assembled worked excellently for me during my enjoyable Hawaii vacation. The directional loop antenna provided nulls on medium wave of 30 dB during preliminary tests indoors, a less-than-ideal test situation.

Waikoloa Beach–just one of a zillion picturesque scenes in Hawaii.

Here is a list of what I’ve put together for my DXing “kit”:

    • SDRPlay RSPdx receiver
    • Short USB cable for receiver<>PC connection, with two RFI chokes installed
    • Lenovo X1 tablet— a Windows 10 device with magnetically attached keyboard; this model is a competitor to Microsoft’s Surface Pro tablet
    • Wellbrook Communications’ ALA1530 head amp module, modified for female SO239 connectors enabling use of large diameter LMR-600 coaxial cable as a 2-turn loop element. My antenna setup is similar to Wellbrook’s commercial flexible loop
    • Wooden base for the antenna (ALA1530 is bolted to the base)
    • 20 feet of lightweight RG-174 coax
    • Wellbrook DC interface module for the ALA1530
    • 3.0 Ah LiFePO4 rechargeable battery for the Wellbrook antenna
    • 15 foot long section of high grade “Times Mfg.” LMR-600 coax cable with PL259 connectors (bought from Ebay already assembled/soldered)
    • Fold-up beach mat
    • Small day pack to hold everything

All the contents of this DXing setup fit a standard size day pack.

You’ll note the absence of headphones in the list. This is because my intent from the start was to record all the DX (MW band) as SDR WAV files for DXing post-vacation. That said, I did have headphones in my travel luggage for later spot checks of a few frequencies. That’s how I found 576 kHz Yangon, Myanmar lurking at their 1700 sign-off with national anthem and English announcement. The remainder of the DX to be uncovered will have to wait until I’m back home near Seattle!

The LMR-600 is a very thick and stiff coax cable, whose diameter approaches that used in the standard aluminum tubing ALA1530 series from Wellbrook. It has the benefit of being self-supporting in a 2-turn configuration and will also coil up into an approx. 12-inch package for transport. It just barely fits within the day pack I’m using. As I understand it, magnetic loops with tubing or large coax as the active element, versus simple wire, are more efficient in operation. Whether or not this holds true in practice remains to be seen.

I fashioned a wooden disc 3/4″ thick to attach the ALA1530 head amplifier, as I didn’t want to bring along a tripod or other support stand. The Wellbrook antennas all work well near or at ground level, so I was able to get great reception with the antenna right on the beach. The diameter at two turns of the coax is only a few inches smaller diameter than Wellbrook’s aluminum tubing loops. Three strips of strategically placed Velcro straps help keep the turns together when deployed as well as during storage.

In theory a two-turn loop should give 5 dB less gain than a single turn version; however, my older ALA1530 module has 5 dB more gain than the newer “LN” type, according to Andrew Ikin of Wellbrook Communications. The net result is that my two-turn antenna should have equal gain to the larger one-turn variety. Future experimentation with this DIY coax loop antenna is in order!

The Wellbrook loop antenna, RSPdx receiver, and Windows 10 tablet on the beach in Waikoloa, Hawaii.

Another view of the DXing position. Being this close to the water with my radio gear was unnerving at first, but the wave action on a calm Hawaii beach is totally different from the Oregon/Washington beaches with waves that can move in and out by a hundred feet or more.

The Wellbrook “DIY FlexLoop” works fine at beach level, and is less conspicuous this way, too.

The ALA1530 module is bolted to the 11-inch wooden disc for support. I’ve modified the module’s sockets to securely hold SO239 female connectors.

The commercial Wellbrook FLX1530LN is a fine product, and worthy of your consideration as a compact and high performance travel antenna. Full details can be found at this link.

SDR WAV Files for Download

One of my goals from the start for my Hawaii trip was to bring back SDR “IQ” WAV files for sharing with others. These approx. 900 Mb files cover the entire medium wave band as heard from my beach location in Waikoloa.

The overall page is: https://archive.org/details/@4nradio   Clicking on any of the entries will bring you to a details page. From there just right click on the “WAVE” link, and choose “Save as…” to download. For a few of the recordings I also posted the file that precedes the one that goes across the top-of-the-hour, because things seemed a bit more lively prior to 1700 (which  was at local sunrise, give or take a couple of minutes).

The IQ WAV files are only playable with suitable SDR radio software: SDRuno is first choice (but you need a RSP receiver connected). The files are also is compatible with HDSDR and SDR-Console V3. It may also play on Studio 1 software.

I hope other DXers enjoy the chance to tune through the MW band, as heard from the Big Island of Hawaii.

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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New Product: Tecsun AN-48x (now available)

Anon-Co just announced that Tecsun has released their new portable, active loop antenna – the AN-48x (27.99 plus shipping) – and it is available for purchase.  Copied below is their announcement:

Tecsun has launched its latest antenna which is now available at Anon-Co! This active loop antenna has a portable design and aims to enhance AM (LW, MW, SW) frequencies. The antenna comes with three types of connector cable and a ferrite coupler for connecting to different types of radios.

Personally, I like my TG34 (DE31MS equivalent).  Though I have *no* experience with this model – as it is new – this is the type of antenna users either love or hate.  My TG34 and the equivalents will amplify everything, including noise, but it has helped me make inaudible or barely audible signals audible.  It’s inexpensive, portable, easy to deploy and store (great for travel) – but it’s really geared towards the SWL hobbyist who can’t invest in, or erect, something bigger and/or more expensive.

The biggest advantage that I can see with this new model: the antenna has three types of connections including BNC & RCA sockets.

Click here for more information: Tecsun AN-48x

Guest post by Troy Riedel

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It’s not a travel radio if it doesn’t have an alarm clock

The CC Skywave SSB is set to wake me at 3:30 to catch a 5:30 flight.

I have a pretty accurate body clock. Regardless of when I doze off, I always wake up at the same time.

When I’m at home on my regular schedule, I trust my “internal chronometer” so much, I haven’t set an alarm in years.

When I travel, it’s a completely different story…

It’s a rare occurrence when a flight, train, or even road trip allow me to wake up at my normal time, so I rely on an alarm clock.

In fact, I’ll let you in on a little secret: I’m a nervous Nellie when I’m forced to break my sleep cycle to catch an early flight. My fear of missing a flight may even border on paranoia–I’ll wake up multiple times during the night in a panic unless I feel completely at ease that there’s an alarm system in place to wake me no matter what.

I recently told a friend about this fear and he asked, “Why not just set the alarm on your phone?!”

Simple answer: I don’t trust smart phones and tablets. They’re too complicated with so many nighttime settings, alarm/alert volume levels, short battery life, etc. etc.

Case in point…

Earlier this year, I had to catch an early flight and needed to wake up at 4:00 AM, so I scheduled my iPhone and iPad to alarm at 4:00. (When at home, I try to have my iPhone/iPad wake me first, because the alarm is very gradual and doesn’t disturb my wife.) Of course, I also set my travel radio’s alarm clock for 4:10, as a fail safe.

Knowing I had a total of three(!!!) alarm clocks set, I slept like a baby.

At 4:10 AM, my travel radio alarm started beeping. The iPhone and iPad were completely silent.

Turns out, the iPad decided to do an operating system update during the night. For some reason, after rebooting, it simply forgot about the alarm. (Thanks, iPad!) And the iPhone? I’m still not sure how/why, but the mute switch on the side of the phone was engaged and if it vibrated to wake me, I never heard it rumbling on the night stand.

Thank goodness the travel radio had my back, else I would have missed that flight.

Travel radios: Never leave home without one!

I like to be a self-sufficient traveler even though I only travel with one bag and pack very lightly. I never rely on my destination to have a functioning alarm clock (with battery backup, of course) or effective wake up call service. Regardless of how minimally I pack, I always take a travel radio.

In February, for example, I travelled to Philadelphia for the Winter SWL Fest. Even though my trip was nearly a week long, to keep from paying a carry-on fee with Frontier airlines, I packed everything in a bag that met their strict “personal carry-on” bag size.

Regular readers know I’m a bit of a pack geek, so my bag of choice was the Tom Bihn Stowaway.  Here’s the bag fully packed out at my feet in the airport:

Here’s a photo of everything I packed in the Stowaway for that trip:

This particular trip really pushed the limits on my minimalist travel philosophy. Honestly? It was a fun challenge! I had to hone my pack contents down to only the essentials (don’t make fun of me for believing three flashlights were essential–the previous year, our hotel was without power for several days).

Still, I made room for one of the smallest travel radios in my arsenal: the County Comm Marathon ETFR:

I chose the ETFR because it has a custom case that could attach to my belt or pack strap if interior space became too tight. The ETFR radio hasn’t been in production for a decade, but it’s an effective radio companion and the alarm works without fail.

Choosing a travel radio

Most modern digital portables are based on DSP chips that have clock and alarm functions, so you might already own an effective travel radio.

With that said, I always prioritize radio features that benefit a traveler, of course; here are some that I look for:

  • Small size: Naturally, it’s sensible to look for a travel radio that’s small for its receiver class for ease in packing.
  • Overall sturdy chassis: Any travel radio should have a sturdy body case that can withstand the rigors of travel.
  • Built-in Alarm/Sleep Timer functions: We’ve already exhausted this topic, right?.
  • Powered by AA batteries: While the newer lithium ion battery packs are fairly efficient, I still prefer the AA battery standard, which allows me to obtain batteries as needed in most settings; a fresh set of alkaline (or freshly-charged) batteries will power most portables for hours on end.
  • Standard USB charging cable: If I can charge batteries internally, a USB charging cable can simply plug into my smart phone’s USB power adapter or the USB port on my laptop; no extra “wall wart” equals less weight and less annoyance.
  • ETM: Many new digital portables have an ETM function which allow auto-scanning of a radio band (AM/FM/SW), saving what it finds in temporary memory locations–a great way to get a quick overview of stations.  (As this function typically takes several minutes to complete on shortwave, I usually set it before unpacking or taking a shower. When I return to my radio, it’s ready to browse.)
  • Single-Side Band: While I rarely listen to SSB broadcasts when traveling, I still like to pack an SSB-capable receiver–especially for longer trips.
  • RDS: Though an RDS (Radio Data System) is FM-only, it’s a great feature for identifying station call signs and genre (i.e., public radio, rock, pop, country, jazz, classical, etc.)
  • External antenna jack: I like to carry a reel-type or clip-on wire external antenna if I plan to spend serious time SWLing. Having a built-in external jack means that the connection is easy, no need to bother with wire and an alligator clip to the telescoping whip.
  • Tuning wheel/knob: Since I spend a lot of time band-scanning while travelling, I prefer a tactile wheel or knob for tuning my travel radio.
  • Key lock: Most radios have a key lock to prevent accidentally turning a radio on in transit–but with a travel radio, it’s especially important to have a key lock that can’t be accidentally disengaged.
  • LED flashlight: Very few radios have this, but it’s handy to have when travelling. Note that the County Comm ETFR (above) does!
  • Temperature display: Many DSP-based radios have a built-in thermometer and temperature display; I like this when I travel anytime, but especially when I’m camping.

While I don’t have a portable that meets 100% of the above travel radio wish-list, I do have several that score very highly.

Since this is a favorite topic, I’ve written a number of articles with reviews of travel radios. In my CC Skywave SSB review last year, I list a number of current favorites.

I should also mention that one great deal at time of posting is the Eton Executive Traveler.

It’s a brilliant little radio for $34.99 shipped (note this affiliate link supports the SWLing Post).

One of our readers has been following the price of this little radio for months–it’s being sold at an all-time low at present.

What’s in your travel pack?

What’s your favorite travel radio? What features are important to you? Anyone else paranoid about missing early flights? 

Please comment!


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Dan seeks a comprehensive travel radio

Many thanks to SWLing Post contributor, Dan Srebnick, who writes:

Here’s a question to put to your blog readers. I’m looking for a compact portable receiver for travel purposes.

It must have AM, FM and shortwave coverage. It should support SSB and RDS. Synchronous AM is a plus, as is FM band coverage starting at 76 MHz (trip to Japan in the near future). Accurate digital readout is a must. But most importantly, MP3 and or wav recording at 48k should be supported. This last point seems to be a showstopper.

But, I’ll be in Brazil, Uruguay and Argentina soon and hope to capture some hard to hear signals. So, any ideas would be most appreciated.

Digitech AR-1780 (left) and XHDATA D-808 (right)

The XHDATA D-808 should fit the bill with two exceptions: synchronous detection and audio recording. The very similar Digitech AR-1780 should as well, although I’m not certain you can switch it to Japan FM frequencies (I bet there’s a hack to do it, although I’ve never tried).

As you suspect, built-in recording is certainly the feature that’s most difficult to find in a portable shortwave radio. The only shortwave receiver I’ve tested recently that has decent built-in recording is the Audiomax SRW-710S (a.k.a. Tivdio V-115). However, it lacks many of the other features you noted and isn’t on par with the D-808 in terms of receiver (it is quite cheap though). I’m not sure I’d rely on it for extended travels.

In your shoes, I might combine the XHDATA D-808 and the Zoom H1n to achieve all of your goals. True, it’s not all-in-one, but it should perform well and the H1n would allow you to do other types of field recording.

Update: One more thought… Although this isn’t a traditional portable radio, you might also consider grabbing the new AirSpy HF+ Discovery SDR and pairing it with a tablet or laptop. It’s a phenomenal receiver and ticks all of the boxes above.

Post Readers: Can you think of other options for Dan? Has another recording shortwave radio hit the market?  What radio or kit do you use for travel and field recordings?  Please comment!

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