Author Archive

Hams on Strava

Count me amongst those who consider DXpeditioning and radiosport contesting true sports on par with chess, professional poker, America’s Cup sailing, and similar pursuits. Operating SO2R for 48 hours straight in CQ WW, chasing WRTC qualification, and pounding out 160m Qs all night from sub-Antarctic Islands are not for the faint of heart, literally!

No surprise, then, that many DXers and Contesters also participate in endurance sports such as running, cycling, and triathlon when not on the radio. The ‘king’ contester/endurance athlete must be Thomas OZ1AA who spent five years cycling around the world and operated contests from whatever country he happened to be riding through along the way. Thomas’ amazing Cycling The Globe Blog is here:

Thomas logged his cycling travels on Strava, a smartphone app that uses GPS to track cycling, running, and other sports, with share/compare social media functionality. Think of Strava as Logbook of the World for cycling and running. Thomas’ Strava feed is here:

Are there other hams on Strava? Yes! At Force 12, yours truly (AA7XT, triathlon) and Jon (KL2A, running) are both active Strava users:

If you look at the Strava users that Jon and I follow, you’ll see many DXers and contesters including Juan TG9AJR, Mark N5OT, Jeff N5TJ (CQ WW World Record Holder and an accomplished bicycle racer), and many more. There are also numerous ham oriented Strava Groups. I’m a member of  the “DXCC” and “DX Runners” groups.

If you’re on Strava or are going to sign up (it’s free!), please do connect with Jon and myself. Maybe we can have a meetup at Dayton and go for a morning group run? Or create a combo annual contest points + mileage Strava Challenge?

I should note that Force 12 engineer/builder Jeremy KE0CGU is the best athlete at the company but does not use Strava (Jeremy prefers his time outside to be away from gadgets – purist!). Jeremy commutes to F12 via bike regardless of the weather and also has competed in mountain ultra-running and long distance mountain bike events.

Ionosondes, the “Fish Finders” of the Ionosphere, and How Ham Radio Can Help Advance Ionospheric Science

Part 1 of a 3 part Blog
Part 2 will cover the RBN – Reverse Beacon Network &
Part 3 will describe the RBN Node @ WØLFA

An ionosonde is a portmanteau for “ionospheric sounder,” instruments managed by educational, government, military and scientific agencies around the world 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. A thorough history of ionosondes written in 1998 by Dr.Klaus Bibl is downloaded in PDF from the Annals of Geophysics Website here:

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.

One of the four crossed-loop receive antennas used at the now-decommissioned ionosonde site in Lerwick, Shetland Islands (

Ionospheric weather, like tropospheric weather closer to earth, is in constant flux. The global ionosonde network is periodically mapping the ionosphere measuring the highest frequency reflected back to earth (this is Fc, the critical frequency) and at what height above earth that occurs (which reveals which ionospheric layer is in play). 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. Here is an example of an ionosonde ionogram (vertical axis is km above ground, horizontal axis is frequency in MHz):
Ionogram produced by a Lowell Digisonde, with explanations for various indications and recordings.
Annotated ionogram from Wikipedia (

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.

Q: why is the MUF so much higher than the Fc? A: 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.

(In addition to electron density profiles, ionosondes can measure Doppler shifts and polarization of ionospheric echoes. Why hams should care about ordinary and extraordinary waves and the polarization of ionospheric propagated signals will be the topic of a future WØLFA Blog post.)

How many ionosondes are in regular operation around the world and are reporting their data publicly? Best I can tell, it’s something around one hundred. The UK Solar System Data Centre has an interactive map (reproduced below) with data on each site, more info at
World map of ionosondes
A hundred ionosondes (+/-) is ‘not nothing,’ however, the world’s a big place, and there are large ionospheric regions going unmapped by the ionosonde network. That’s where ham radio comes to the party.

The number of amateur radio operators communicating long distances over shortwave on any given day vastly outnumbers active ionosondes by orders of magnitude. Two of the most popular ham activities are contesting, making as many contacts with as many other hams in as many countries as possible in a given period, typically over a weekend, and DXing, contacting as many countries as possible in one’s lifetime during or outside of contests, the more obscure and hard-to-contact, the better.

“Contesters” and “DXers,” which are not mutually exclusive groups, 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 snag an elusive country.

Hams have developed several innovative tools to collect, correlate and analyze the large number of ionospheric observations taking place on the ham bands every day. Every successful contact, a “QSO’ in ham-speak, is a data point. The American Radio Relay League’s Logbook of the World database is closing in on a billion QSO records from over 80,000 contributors! More data = better science.

Part 2 of this Blog will discuss two of the ways hams are collecting and analyzing ham radio-generated ionospheric propagation data in real-time: RBN, the Reverse Beacon Network, and
Part 3 will describe the RBN Node @ WØLFA.

Satellite Operation @ WØLFA

I recently set up a satellite station at WØLFA to see how well the GØKSC-designed InnovAntennas LFA Yagis, which work so well on VHF and UHF terrestrial weak signal modes, would work with the amateur radio satellites. Up went a five element LFA for 2m (2 LFA 5) and a ten element LFA for 70cm (70 LFA 10). The 2m LFA was tuned for 146 MHz and the 70cm LFA was tuned for 436 MHz to put them near the center of the satellite subbands, simple adjustments of the LFA driven element loop in each case. The LFAs were mounted vertically so that the aluminum cross-arm would not disrupt their highly-optimized, low sidelobe designs.

Both Yagis are relatively compact and sit about eight feet above ground on a Glen Martin Engineering ‘Quadpod’ tower mounted just behind the WØLFA shack. SSB-Electronic LNA SP-200 & SP-70 preamps with VOX sensed T/R relays are mounted on the tower close to the antennas to optimize system performance. Since satellite operation is low power, I opted for the simplicity of the VOX capability built into the SSB LNAs; less wires is always a good thing!

Positioning is provided by an AlfaSpid RAS rotator controlled by a rack-mounted AlfaSpid MD-01 controller. Rig is a Yaesu FT-847, the only non-SDR radio @ WØLFA, which I kept around solely for satellite use as our SDR rigs, as much as I love them, don’t (yet) have the full-duplex features needed for serious satellite operation. Satellite tracking is handled by SatPC32 software running on a Windows 7 64 PC. SatPC32 communicates with the FT-847 via a serial port null modem cable and with the MD-01 via a standard straight-through serial cable on a second serial port.

Here is what the XW-1 (Xi Wang 1 aka Hope OSCAR or HO-68) ham satellite sounded like at WØLFA on Aug 10, 2015 at around 03:30 UTC. XW-1 was launched in 2009 from the Taiyuan Satellite Launch Center in Shanxi province, China. After about a year, the transponder failed, however, the little ‘bird’ (68 x 48cm) continues to orbit and its 200 mW (2/10th of one Watt!) Morse code beacon continues to transmit. Note the manual Doppler correction! (I have since enabled the automatic Doppler correction feature in SatPC32.)

All of the antenna system items used here, from InnovAntennas, AlfaSpid, and SSB-Electronic, are available from the Force 12 Superstore.

My first 50-MHz QSOs with Japan from new Colorado QTH

I made contact with 19 Japanese stations yesterday afternoon (June 14, 2013) on the 50-MHz (6 meter) band between 2314 and 2356 UTC.  This was my first “JA opening” on 50-MHz in a LONG time; my last Japanese QSOs on 50-MHz were back in the ’90s when we lived in Tiffany, Colorado (grid square DM67), a bit south of our new home in Glade Park, Colorado (grid square DM59pa). During the years we lived in Vermont the furthest west I ever reached on 50-MHz was Guam, a bit short of Japan.

If I’m anywhere near my radio (and sometimes when I’m not – thank you, smartphone) I point a Web browser at the “ON4KST 50 MHz IARU Region 2″ chat page to read late breaking 50-MHz DX related news, spots, rumors and general chatter especially during during times of the year when 50 MHz propagation is known to be possible:

  • Around the spring and autumn equinoxes for Trans-Equatorial Propagation (TEP)
  • May through the first half of August for the northern hemisphere summer Sporadic-E (Es) season
  • A few weeks either side of New Year’s Day for the northern hemisphere winter Es season sometimes with propagation links to the southern hemisphere
  • And – if we had more sunspots than Cycle 24 has seen fit thus far to bequeath – the northern hemisphere autumn and winter for F2 propagation

(Of course 50-MHz can open at any time of day and year and much of what happens on “The Magic Band” is poorly understood.  But the periods above are the ‘prime time for six.’)

It all began yesterday afternoon at 2200 UTC (which was 4 pm Colorado time) when Han JE1BMJ, a noted 50-MHz enthusiast and propagation theorist, was reported on 50,090.5 kHz by Jay K0GU on the ‘KST chat which grabbed my attention.  Jay lives in Wellington, Colorado (grid square DN70mq) about 230 miles east of me and is a dedicated, experienced 50-MHz DXer.  Jay hears a lot of stations before any one else in the Rocky Mountain region and his ‘KST posts are always worth noting.  I turned my new 50-MHz antenna (thanks to K7JA for assistance in building and installing this last month and of course G0KSC for the design) towards Japan – 312 degrees azimuth – and started listening.  At 2226 UTC I started hearing Han’s CW (Morse Code) signal slowly fade and out.

Green Heron RT-20D controlling a Spid RAK rotator

Green Heron RT-20D controlling a Spid RAK rotator

When I first attempted to make contact with Han but he was unable to hear my complete callsign and was responding to me as “AA7X” (leaving off the final T, I am AA7XT).  I eventually stopped calling JE1BMJ – I didn’t want to ‘hog the DX’ as Han and other Japanese stations were being heard over much of the US.  For a two-way contact to be considered legitimate in ham radio circles each party must copy correctly the other parties callsign and preferably some other information such as a signal report. caught the action! caught the action!

At 2314 I noticed Han’s signal had gotten louder so I called him again and made a solid contact straight away.  Success!  I was amazed my ‘barefoot’ (no amplifier, only 80 Watts output) Elecraft K3 transceiver and InnovAntennas 8 element LFA Yagi (an awesome antenna but it was on a tower parked at only 3 meters [10 feet ]above ground due to recent high winds) were making the 9,000 kilometer journey!  At ten feet up towards Japan my antenna was looking into a hillside!  I listened to Han work other stations for a few few minutes and savored the moment.

InnovAntennas 8 element 50-MHz LFA Yagi

InnovAntennas 8 element 50-MHz LFA Yagi

Here’s a short YouTube video I made of JE1BMJ’s signal yesterday:

I would have likely made many more contacts if had started calling CQ earlier!  For a long time I was only hearing JE1BMJ so I didn’t bother calling CQ until around a full hour after opening started.  I had an ‘instant pileup’ after first my CQ call; clearly I should have started CQing much earlier – Doh!  I proceeded to work 18 more Japanese stations before the path closed:



Toshi ,JA0RUG, who I worked during this opening, sent me a MP3 recording of my signal as heard in Japan (click on link to listen to the audio):


Here are the grids I worked during yesterday’s opening:

The WG7J Gridmapper is a great post opening analysis tool

The WG7J Gridmapper is a great post opening analysis tool

The first hop was certainly Es as I was hearing loud stations in Oregon, Washington and British Columbia at reasonable Es single distance, but how about the rest of the way?  Han, JE1BMJ, the first station I worked in this opening, has developed a theory on these openings – which cluster around the summer solstice – and he has dubbed the mechanism “Short-path Summer Solstice Propagation” aka SSSP.  Articles on SSSP by JE1BMJ, W3ZZ, WB2AMU and KH6/K6MIO have been published in Dubus, CQ VHF, Six News and elsewhere.  Here are a few links:

So far, SSSP, if it in fact exists (such mysteries make 50-MHz DXing a fascinating avocation!) seems to be unique to the 50-MHz band.  I look forward to learning more about SSSP as more and more DXers become aware of the mode and watch for it.  Ham Radio is the exception to the ‘watched pot never boils’ rule of thumb.  In DXing, an unwatched band never opens!  One interesting note is that propagation like SSSP frequently repeats itself the next day so you can be sure I will be at my radio this afternoon!

73 and CU on the Magic Band!

Bill AA7XT


PS:  Some interesting recordings of 50-MHz DX signals heard in Japan by JE1BMJ can be found here (including yours truly):

Pipeline To The Arabian Peninsula Over The South Pole

Over the past three days I have made two-way amateur radio contacts (a “QSO” to hams) via an unusual short wave propagation path – the long way, over the south pole – from my home in Glade Park, Colorado to amateur radio stations in the Arabian Peninsula, each day in the late morning my time.  Signals have been surprisingly strong and audible for hours.

Short wave radio signals usually follow the shortest path from point A to point B, the ‘great circle path.’  From my house to the United Arab Emirates this is approximately 13,000-km.  Since the circumference of the earth is just over 40,000-km the long path to the UAE is around 27,000-km and crosses the equator twice!  The DX Atlas Map below has markers for my home (QTH), where the map is centered, and the UAE and also shows the location of the sun, dusk/dawn zones and areas of darkness for 1744z on January 5, 2013 (this is the time for one of the YouTube videos I made of this event).

DX Atlas A65BP -> AA7XT 2013-01-05 1744z

Here are the QSOs I’ve made over this path (so far, fingers crossed this path will be here tomorrow and beyond):

  • Jan 3     1805z     A65BR     28076-kHz     JT65A
  • Jan 4     1839z     A65BP     24893-kHz      CW
  • Jan 4     1844z     A45XR     24902-kHz     CW
  • Jan 5     1702z     A45XR     28009-kHz     CW

My four contacts were made with a simple vertical antenna and 100-watts transmitter power (except for the JT65A mode contact which was made with a mere 10-watts).  The footprint of the propagation was very specific – the southern Arabian/Persian Gulf area on one end and western North America on the other.  Here is what the A65BP DX Cluster spots looked like as of this morning.  You can get a feel for the where the signals were landing in this part of the world from the spotting stations’ locations:

Screen Shot 2013-01-05 at 6.35.36

Why did this path open now?  A recent spike in the solar flux above 140 helped refract the 25/28-MHz radio waves a long distance, a ‘quiet sun’ (low Kp and Ap indexes) helped the signals transverse the auroral zone around the south pole and a double crossing the trans-equatorial zone – where radio waves from the upper HF all way up to low UHF can get a turbo boost plus the seasonal geometry of the sun and earth which puts a lot of solar radiation in the southern hemisphere all played a part.  I wonder if higher solar flux would have resulted in a rare (for the USA) long path opening in the amateur 50-MHz (6 meter) band?

Here is a recording of A65BP operating from the United Arab Emirates with a great signal on 28,012.26-kHz as heard in Glade Park, Colorado (DM59pa) today 2013-Jan-05 morning at 1743z with a simple vertical antenna. The signal was propagating via long path over the south pole. A45XR was also strong on 10m CW on this path around this time. I completed QSOs with A65BP and A45XR on 24.9-MHz long path on January 4th and had a 28,076-kHz JT65A QSO with A65BR on January 3rd. Nice to hear some 10m long path in Cycle 24!

Here is a recording of A65BP operating from the United Arab Emirates just a little later with a great signal on 24,902.00-kHz, also captured with a simple vertical antenna.

These last few days have really lit a fire under me to get off my ass and build the 3-element 12-meter LFA Yagi and 5-element 10-meter LFA Yagi from InnovAntennas that are sitting in my shed.  If I can work stuff like this on my vertical what will I be able to do with a pair of state-of-art antennas?  Who cares that hasn’t been above freezing here since December 17th when there is DX to be worked!

(Sunday morning update – A92GR & VU2XO are audible on 10m SSB at approximately 1600z, looks like another good morning on the long path.)

Planning My New QTH (Ham Radio Station) Part II Of III: Modern Contesting Tools

I’ll be writing a lot in future postings about how FlexRadio’s new 6000 series transceiver technology has influenced my new station’s design.  Today’s post will focus on these rigs’  ‘Slice Receiver’ capabilities.

First, however, allow me a digression on 21st Century Radio-Sport a/k/a “Contesting.”  There are hundreds of radio-sport events spread across the calendar each year from state QSO (QSO = radio contact) parties to major global events such as the CQ World Wide DX Contests (CQ WW DX, ‘DX’ = long distance radio contact) held across two weekends – one for CW (Morse code) and one for Phone (Signal Sideband = voice) –  in the northern hemisphere autumn.  The smaller events have a friendly ‘small town’ vibe.  On the other end of the scale, the big DX contests are hard fought struggles that test technology, skill and endurance (you try averaging two international contacts via morse code per minute for 48 hours straight!).

The big contests have a multitude of classes to parse the competitors.  Single operator, multiple operators with one transmitter, multiple operators with multiple transmitters, high power, low power, really low power (also known as ‘QRP’), assisted and unassisted.  You compete against others in your class in your country and in your class on a regional and global scale depending on your ambition.

I mentioned ‘assisted’ and ‘unassisted’ classes in the previous paragraph.  This can mean various things but the major source of assistance during a contest is the so-called ‘cluster’, Internet resources that reports what stations are active and on what frequencies.  These networks started in the ’80s with hams transmitting short reports of the distant stations they were hearing, generally on the HF (short wave) bands, via the amateur VHF digital networks which were generally local, within a city or region.  These were know as ‘DX Packetclusters’ back then and I used to operate a node in Tiffany, Colorado in the ’90s.

These networks later migrated to the Internet, became interconnected and are now global in scope passing literally millions of ‘spots’ (as each report of a station and its frequency is called).  DX Summit, based in Finland but with visitors from around the world, has reported over 23 million such spots since it launched in 1997!

One of the challenges of big data is finding actionable useful information shooting out of the digital firehose.  The cluster networks go bonkers during the big contests with several spots per second streaming by.  This is not always helpful.  An operator can be overwhelmed by choice; which station do I try to contact?  It’s like getting a restaurant menu with a thousand choices.  And with spots being reported from all corners of the planet much of the data is not actionable.  A station being heard in say Mongolia might not be making it to your shack in Peoria at that time of day on that particular frequency.

I will manage this onslaught of data by disconnecting from the Internet clusters and generating my own spots distilled from radio signals actually being detected at my station in real time.  The data will thus become relevant and actionable.  Many stations are already doing this to supplement the Internet spots that every assisted class station sees.  K3LR and W3LPL, two giants of multi-operator contesting, are doing this effectively using CW Skimmer software written by Alex Shovkoplyas, VE3NEA.  CW Skimmer uses ‘sensitive CW decoding algorithm based on the methods of Bayesian statistics’; in other words your computer listens for Morse code on your radio and tells you who is transmitting and on what frequency.  CW Skimmer, of course, is not much use in Phone (voice) contests.

There are several challenges to using CW Skimmer effectively.  The first challenge at most stations is receiver bandwidth.  Most ham radios can only listen to relatively small segments of radio spectrum at any one time limiting the size of the net CW Skimmer can cast.  If a particular contest has its competitors spread out over say 70-kHz and your radio can only monitor 2.8-kHz you are going to miss a lot of the action.  So called SDRs (Software Defined Receivers) overcome this limitation and can look at much larger chunks of spectrum at once.  An operator using one of these radios (older generation FlexRadios for example) can actually look at a visual spectral display showing where signals are and indicate their relative strength; a CW Skimmer software working with one of these radios can decode and report on the activity of dozens of stations with this set up.

That hurdle jumped, another one looms ahead.  If you are monitoring stations on one band how do you know what’s happening on other bands?  Most contests are spread across several of the amateur radio bands.  Some bands are good during the day, some are good during the night and propagation on all the bands is always changing.  Europe might be good in the morning on a particular band , say the 21-MHz (15m) band, Africa in midday and Japan in the afternoon.  The general propagation trends are predictable but there are large daily variations in propagation that are not predictable (in other words, what signals are being refracted back to earth and where).  Some stations (K3LR, for example) have separate SDRs for each amateur contest band.  Other stations (W3LPL for one) uses the QS1R receiver which can listen to several bands at once.

The Flex 6000 series radios listen (via direct sampling, more on that in a future posting) to 77-MHz of spectrum at the same time.  That is truly spectacular!  With my multiple Flex-6700s (I have two on order and plan on ordering a third unit later in 2013) i will be able to assign ‘Slice’ receivers (each Flex-6700 can have up to eight of these, created in software and 384-kHz) to each amateur band from 1.8-MHz (160m) to 144-MHz (2m) and let them run all the time, during contests and in between.  I will have live, actionable intel on what CW (Morse) signals are propagating to Glade Park, Colorado at any given time on all the amateur bands.  I will be feeding this data out to the Reverse Beacon Network (RBN) and using it for my own contesting and day-to-day DXing operation.  (More on the RBN in a future Blog posting.)

How I plan to keep transmissions on one frequency from overloading and possibly damaging receivers listening – and running CW Skimmer software – on other frequencies on co-located (and sometimes the same) antenna will be covered in a future posting.  The Flex 6000 series radios are full-duplex (in other words, they can transmit and receive at the same time) so the listening on the same band I’m transmitting on becomes a possibility but one with significant challenges.

I should point out here that many hams operate without any kind of assistance in contests whatsoever.  These are some of the world’s most skilled and motivated amateur radio operators and I admire this type of contesting.  However, my personal current motivation is to see where I can go with technology in contesting and amateur radio in general.  Assisted, in so many words, but seeking innovation.


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