Category Archives: DX

Articles and information about DX or distant stations outside the North American continent. Topics include working DX, DXpeditions, DX Stations, DX related antennas, software, and equipment and more.

Chasing those elusive Asian QSOs

Background: On December 4, 2017, I was making some casual FT8 QSOs on 40 meters when out of the blue, JR7AMZ answers my CQ. It was 6 pm local and the band was full of the usual Europeans. What a totally unexpected surprise! Working Asia from New England is a huge challenge usually requiring multi-element direct beams. And my verticals were beaming toward Europe.

 Today, December 15th, I was up at 6 am, a little earlier than usual and for some reason, I had a desire to work Asia. So I configured my verticals for broadside bi-directional pattern of 160 and 340 degrees. ( If not the short path, maybe I can catch an Asian on the long path.)

Contesters and DXer tend to be very knowledgeable about radio propagation from their own extensive observations. Knowing what bands to operate on and at what times given the current state of the ionosphere can give a “contester” a winning edge or help a DXer contact an elusive country. Let’s look at the mechanics of long skip propagation:

If the frequency is too high, your signal will not be reflected and your RF will be ‘out of this world’. But there is one ideal frequency wherein your signal will be reflected for the longest distance. With the proper vertical wave angle, you can get up to 1800 miles. Beyond that, you need multiple hops. The more hops, the lower the signal strength due to reflection losses.

Typical ground reflection losses for DX hops are 3 dB for poorly conducting ground and 0.5 dB for sea water. 3dB represents a loss of half the signal.

With 11-bands to choose, how do I determine the proper band to use on a real-time basis? I could go to the Reverse Beacon Network ( and configure it to display 100 spots received from spotters in Zone 5 and scroll down till I find Asian stations spotted. But remember these are reports of stations already received, worked, and spotted.

Or I could go to VOACAP ( and see the “prediction” for the New England to Asia path. See:

An ionosonde results from an “ionospheric sounder” instrument used to monitor and measure the ionosphere. You can think of Ionosondes as ‘fish finders’ that find, instead of schools of fish, regions of electrons and electrically charged atoms and molecules in the upper atmosphere.

The first ionosondes were invented in the 1920s, grew in sophistication during the 1930s, and were used by both sides during WWII to identify the best shortwave communication frequencies. Ionosonde systems incorporate a transmitter tunable from as low as 500-kHz to as high at 40-MHz (1.6 to 12-MHz sweeps are a more typical range), antennas usually pointed straight up, and a receiver that tracks the transmitter listening for echoes reflected back to earth. It is, in other words, a radar system.

The Ionosphere is in constant flux. The global ionosonde network is periodically mapping the ionosphere measuring the highest frequency that reflected back to earth (this is Fc, the critical frequency) and at what height above the earth that occurs. The critical frequency is proportional to charged particle density in each ionospheric layer. Signals at frequencies above Fc at the F2 layer (highest ionospheric layer) continue off into space instead of coming back to earth.

Knowing the critical frequency at various points around the world enables calculation of MUF (Maximum Usable Frequency) for shortwave radio broadcast and two-way radio communication in those regions. A useful rule of thumb is the MUF will be around three times the Fc. So, for a Fc of 6.2-MHz, the MUF for signals transiting that region of the ionosphere would be around 18.7-MHz. In such conditions, the amateur 17-meter band, centered on 18.1-MHz, would be a great choice for long distance communication, as would the 20-meter band (14-MHz). The 15-meter band (21 MHz), on the other hand, would likely be ‘dead’ for paths across that region.

Why is the MUF so much higher than the Fc? Radio waves propagated over long distances are refracted (bent) back to earth at acute angles, not ‘bounced’ back to earth like a handball off a wall. Less ionization is needed for refraction at low angles than for a return of a signal transmitted straight up. (See

Now the magic begins. To determine the MUF for your location is one thing. But for a circuit, you need the MUF at the destination. Then, for obvious reasons, your band choice would be the lower of the two.

From this website, you will find Sounders around the world:

We are lucky as one sounder is in our backyard: MHJ45 Millstone Hill, Westford, MA. For Asia, I use JJ433 Jeju Island, Korea which is an island off the South Coast of Korea.

It’s 5 am. Millstone shows MUF 9.68 MHz and Jeju 8.57 MHz so 40 meters would be the frequency. Sure enough, the FT8 decoder shows JE7JDL and JH0INP working many stateside QSOs. No luck! Now at 6 am, Millstone shows MUF 15.11 MHz and Jeju 9.15 MHz. Time to switch to 30 meters. There’s JA7WND, JK1IQK, and JE8CIC! I keep calling not to no avail. Maybe next time!

At Least I know I’m on the right frequency! I’m confident I work my share of Asian this winter!

73,  Layne AE1N

DX Alarm Clock Part 2 – Hardware

I recently wrote a blog article about the DX Alarm Clock software – here is Part 2 of the Series on the how I built the hardware for the DX Alarm Clock.

DX Alarm Clock Hardware Components

The DX Alarm Clock is based on a Raspberry Pi 3 computer and an Adafruit Pi-TFT Touch Screen Display.  The list of components, along with links is below.  Since I built the Raspberry Pi almost a year ago and technology is always advancing, some of the parts are no longer available or have better replacements available.  I’ll provide information on what I used and a recommended replacement.  Approximate prices are included.

Raspberry Pi 3
Raspberry Pi 3

Motherboard: Raspberry Pi 3 ($35) – includes a 1.2 GHz 64-bit quad-core ARM CPU, Build in WiFi, Ethernet, 4 USB Ports, an HDMI port and audio port (3.5″) and Bluetooth.

Also, you will need a power adapter  ($10) and Class 10 Micro SD card ($15) for the Raspberry Pi.  Ours is a SanDisk Ultra 64GB Micro SD Card.

Pi-TFT Touch Screen Display
Pi-TFT Touch Screen Display

Display: Adafruit Pi-TFT 2.8″ Display with Capacitive Touch Screen ($45).  A slightly larger, 3.5″ display is now available.

PiBow Case
PiBow Case

Case: Pimoroni PiBow Case for Raspberry Pi and Pi-TFT Display($20)

Kinivo Speaker
Kinivo Speaker

Portable Speaker:  Any small portable/rechargeable speaker will do.  Mine is a Kinivo, but it is no longer available.  Any small speaker will do as long as it is Bluetooth or has a 3.5″ stereo connector.

Completed DX Alarm Clock Hardware
Completed DX Alarm Clock Hardware

The picture above shows the completed DX Alarm Clock Hardware running portable using a USB battery pack.

Raspberry Pi Development Environment

Raspberry Pi Development Environment
Raspberry Pi Development Environment

After constructing the Raspberry Pi, case and TFT Display, the next step was to connect it to a monitor via the HDMI port, a mouse via one of the USB ports and to a Bluetooth keyboard.   Then I loaded the Raspbian Operating System onto the Raspberry Pi via the micro SD card.  I first copied the OS to the Micro SD card using a PC or Mac and then inserted the card into the Raspberry Pi and booted from it.  You can find a good tutorial on how to do this at

Once Raspbian is installed, you will have a windows like GUI (Graphical User Interface) environment with a web browser, and a number of additional applications included.

This gave me a development environment that I could use to build and test the DX Alarm Clock software.  I used the Python language to develop the software.  I used the Python IDLE development environment, which is included in the Raspbian OS.

Interested in Raspberry Pi Amateur Radio Projects?  See the article on a Raspberry Pi Satellite Rotator Interface.

Member Spotlight – B. Scott Andersen, NE1RD

NE1RD on Mt. Wachusett

Bio of B. Scott Andersen, NE1RD

I got my start in ham radio not long ago. In 2002, after years of encouragement from a good friend, I finally looked into the hobby. “You’ll love it,” my friend said. “It’s right up your alley.” I confess I was skeptical, and even a little uncomfortable watching him make a simple call on a 2m radio he had in his car. “Go ahead and talk,” he said. I was well outside my comfort zone.

I’ve tried to remember those feelings as I show new people our world. It can seem strange, and aspects of it still seem strange, even after all these years. “It isn’t just one hobby,” my friend admitted. “It’s 99 different hobbies. You just pick the ones that interest you.”

I have taken his advice, and now I’m involved in some of the ones that most intrigued me. Not long after being licensed, I entered my first contest. It was October of 2002, the sunspots were still active, and I worked over three hundred stations in just a few hours. I was completely hooked on contesting! A lot of the things that made me nervous in the car that day were absent here. There were no long conversations; they just wanted my exchange (5905), and on they went!

The thing that really captured my attention, though, was a DVD of a DXpedition run by the Microlite Penguin team and their trip to South Sandwich Island and Southern Thule. These guys were amazing! Small radios, lightweight gear, well-conceived but modest antennas, and they worked the world. This was something I wanted to do.

So, in the next few years, I spent most of my free time thinking about ham radio, and lightweight DXpeditioning in particular. Contesting just helped me increase my DXCC totals, and hone my skills. The culmination of all that thinking was captured in my blog “The 100 Pound DXpedition.” You can get a PDF of all these brief articles from a link on my website

As part of this DXpeditioning interest, I also spent a great deal of time thinking about antennas, and portable antennas in particular. My book “Buddipole in the Field” was the result of some of this work. You can get the free PDF from the Buddipole User Group on Yahoo!, or from a link on my website. The Buddipole has provided a good platform for many of my experiments, and DXpeditions.

I’ve always been a nerd, interested in electronics, physics, mathematics, and the like. Ham radio has provided me a way to transition from the abstract to the concrete. It is one thing to think about radio theory. It is another to build a working radio. I’ve been building kits since the 1970’s, but ham radio has given me many new opportunities. I’m particularly fond of Elecraft kits having built two K2s, three K1s, and two KX1s. They are all fabulous radios, and building them was deeply satisfying.

I am still working, so ham radio sometimes takes a backseat to my responsibilities, but it is never far from my mind. I’ve also learned just a little patience through all this. Building up a country list for DXCC, and chasing various radio awards must be done over time (usually years) and it has paid off. I now have 8-band DXCC, WAS in both Massachusetts and New Hampshire, ARRL Challenge, and various CQ WPX awards. They look great on my wall and are a reminder that anything worthwhile requires both hard work and patience.

After all this time, I’m still very much a student of the hobby. I’m shameless about asking questions and always try to take advantage of any opportunity to see and try new things. I can only hope that this passion continues through the coming years. It has been a joy for this first fifteen, certainly!

The Bouvet Island DXpedition 2018

Bouvet lies at 54 degrees, 25 minutes South and 3 degrees, 22 minutes East. It’s the product of a volcanic eruption that last occurred in 4,000 B.C.  Bouvet is 97% ice-covered, and with surrounding rocks and small islands, has an area of 19 square miles, with 18.4 miles of coastline.  Its location, ice, rock cliffs, high seas, harsh climate and surrounding pack ice and icebergs isolate it from human presence.  Jean-Baptiste Charles Bouvet de Lozier first saw the island in 1739.  The island was not seen again until 1808.  There was a disputed landing by Benjamin Morrell. But, the first documented landing was by the Norvegia expedition in 1927, which named the island Bouvetoya, and claimed it for Norway. More on the Bouvet Island DXpedition…

Source: The Bouvet DXpedition 2018

The Bouvet Island DXpedition will give us a chance a very rare one! Please consider supporting if you can.

Fred, AB1OC