Category Archives: Guest Posts

Digital Modes, Guest Posts, Kits, News, Portable, QRP, QRP Radios

From idea to kit: Adam introduces the Arduino Digital Modes HF QRP Transceiver (ADX-S) kit

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Many thanks to Adam (BD6CR) who shares the following guest post about his latest project:

From Open Source Project ADX to Kit ADX-S

by Adam (BD6CR)

BD6CR @ CRKits.COM

Original Design: WB2CBA

Modification and Kitting: BD6CR

I knew Barb, WB2CBA from his uSDX design a few years ago and I introduced both DL2MAN and his designs in my blog. So, when I came across the ADX – Arduino Digital Xcvr a few months ago, I immediately ordered both the ADX (through hole) and the ADX UNO (surface mount) PCB samples.

I started building the ADX UNO and put it in a dental floss case and made a few contacts on park bench. However, the soldering is too much for my eyesight. So, I turned back to the ADX because I don’t need to solder any SMD parts, since both the M328P and SI5351 are module based. I could build the project in 3 hours and it worked the first time.

However, I felt unsatisfied with the strong BCI since the CD2003 radio receiver chip was connected as a direct conversion receiver. JE1RAV mentioned in his QP-7C modification project that he tried JA9TTT’s idea to build a superhet SSB receiver with the TA2003 or CD2003, so I tried and it worked very well. I have decided to name the new circuit as ADX-S, where S stands for Superhet.

I shared the great news with Barb and he encouraged me to carry the flag to make it a kit, since my design D4D was his first digital radio and he loved it.

You can refer to Barb’s page on ADX here.

My hardware modification can be outlined in this schematic. I have added an FL1, PFB455JR ceramic filter by Murata and a C25 coupling capacitor from CLK2 of SI5351 module. The RX audio comes from pin 11 instead of pin 4.

I modified it by cutting two traces on the ADX PCB and it looked ugly, so I redrew the PCB. Continue reading From idea to kit: Adam introduces the Arduino Digital Modes HF QRP Transceiver (ADX-S) kit →

Antennas, Articles, Comparisons, Digital Modes, Guest Posts, News, QRP

Guest Post: Extreme QRP–Testing the AX1 with WSPR and 20mW

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Many thanks to Keith (KY4KK) who shares the following report:

Extreme QRP – Testing the AX1 with WSPR and 20mW

by Keith (KY4KK)

Thomas, thanks for all of your activation videos related to the Elecraft AX1 antenna.  I ordered one the day you announced the package deal, and it arrived in less than a week.  I’ve activated a few parks with it already (20m SSB).  Like you and many others, I’m impressed.

I was very interested in Thomas Barris’ (DM1TBE) March 12 QRPer post using WSPR to test his POTA antennas in Germany.  Then I saw Bob’s (K7ZB) post about his ZachTek Flea with 300 milliwatts in CW mode.  To me, extreme QRP represents some of the magic of HAM radio.  I’d like to share one of my most recent WSPR experiments related to the AX1.

About a year ago, a friend (NG4S) loaned me his pair of WSPR transmitters and suggested that I explore building and comparing antennas. I’ve been hooked on antennas of all kinds and WSPR since then.

I began doing WSPR tests on the AX1 the day after it arrived.  With two transmitters set to the same frequency and power output, you can do direct comparisons between two antennas under identical propagation conditions.

I’ve already done a couple of comparisons between the AX1 and other commercial antennas.  But I think the test I just completed might be of particular interest because it pits the AX1 against an antenna I’ve seen you use many times – a 28.5’ end fed with a 28.5’ counterpoise.  I used 24 AWG silicone insulated wire. The end of the radiator was placed on a 19’5” telescoping fishing pole.  This is my preferred POTA mast when I can’t use a tall tree.

I spent some time trying to control other variables so that the only significant difference during the test would be the antennas themselves.

For example, the SOTA Beam WSPRLite Classic transmitters don’t have an ATU.  So, I had to make the antennas resonant on the 20-meter WSPR frequency of 14.097 MHz.  For the AX1, Thomas’ videos helped a lot.  I used a clip-on capacitance hat and adjusted the counterpoise to 15’ 2”.  This gave me an SWR of 1.17:1.  For the end fed, I tried the two UNUN’s I had available and settled on the 49:1, which got me the closest (2.2:1).  I then used a manual tuner to achieve an SWR of 1.29:1.

I also wanted to deal with the difference in power output between the two transmitters.  Although they’re identical, and both set to 20 milliwatts, there is no way to ensure both are actually producing that output level.  Based on tests by NG4S, one of the transmitters runs at 19 milliwatts.  The other actually outputs 27 milliwatts.  So, my plan was to run the test for 48 hours. At the end of 24 hours, I would switch the transmitters (and callsigns) so that both antennas would benefit (relatively equally) from one of the transmitters being stronger.

At the end of Day 1, I reviewed the data from the two transmitters on dxplorer.net/wspr.  The end fed averaged a 5.7 dB gain over the AX1 based on reports from receiving stations that spotted both transmitters in the same 10-minute block (simultaneous spots).

On Day 1, the stronger transmitter was on the end fed.  The maps below are from WSPR.rocks.

AX1 – Day 1

End Fed – Day 1

I was pretty impressed that the AX1 got into Europe and Africa on only .019 Watt!  I always have good luck with end feds, so was not too surprised to see this one perform well. Continue reading Guest Post: Extreme QRP–Testing the AX1 with WSPR and 20mW →

Articles, Field Reports, Guest Posts, Portable, POTA, QRP, SOTA

A story about a gluttonous dragon, a princess, a knight, and many DX contacts to the US from a volcano in Germany

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by Thomas (DM1TBE)

Intro

If you have read my previous activation reports, you may remember that the temperature was more often than not below 0° C / 32° F. I am tired of the winter. So I was very pleased when the weather forecast indicated 18° C / 64° F on a Saturday.

In one of my previous posts (How I found the best antenna for my SOTA/POTA activations) I have outlined, that I like using the 30-meter band for being reliable on short and medium distances – in my case, Central Europe. However, I wanted to try an activation with an antenna that is more appropriate for DX. The wire winder for my 30-meter antenna had plenty of space left, so I decided using a commercial 12/17-meter band wire antenna that I have discussed briefly in the report linked at the beginning of this paragraph.

The day before, I built a 20-meter end-fed with parts that I found in my basement and a tiny 1:49 transformer from K6ARK. I added a short coil, so the feed point wouldn’t be at or too close to the ground when using my 10 m / 33 ft fiberglass mast. I know it needs some polish.

The Limburg

The Limburg is a conical summit about a 30-minutes drive from my home. It can be activated for a couple of programs like SOTA (DM/BW-110), POTA (DA-0203), WWFF and COTA.

The Limburg is, or better was, a volcano; technically, a volcanic vent of the Swabian Volcano, a volcanic area of 50 km / 31 mi radius with over 350 volcano vents. Seventeen million years ago, it produced massive gas and dust explosions. Be careful when ramming your antenna groundspike into the ground ;-). So it became a steep summit, elevated around 200 m / 650 ft over its surrounding area.

Earliest traces of population around the summit date to 3000–1800 BC.

Around the year 1050 Duke Berthold I., picture below, built one of the oldest Romanesque castles on the top of the summit. It was the seat of the House of Zähringen, who were related to the House of Hohenstaufen, about whom I wrote in an activation report here earlier: DM1TBE Field Report: Shivering with 18 WPM on the ruins of the medieval Hohenstaufen Castle

Around 50 years later, his son Berthold II. built a new castle some 150 km / 90 mi away and moved the seat of the family. Shortly thereafter, the castle was destroyed (probably, nobody knows exactly). It was rebuilt and destroyed again in 1130 and rebuild again. After the year 1150 a new, larger castle was built not too far away and this castle lost its importance and, eventually, gave up. Continue reading A story about a gluttonous dragon, a princess, a knight, and many DX contacts to the US from a volcano in Germany →

Articles, Field Reports, Guest Posts, Portable, QRP, SOTA

Pilgrimage to Summits on the Air

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by Thomas (DM1TBE)

After a rainy and windy Friday, the weather was expected to improve a bit the next day. The temperature was still forecasted with around 0 °C / 32 °F, but no rain was expected. So, my friend Jochen (DG1PSI) and I thought we could operate outside. We have chosen a summit called Bernhardus. The summit is next to “Kaltes Feld” on the opposite side of the valley, where I was a some days before. With an 1.2 km / 0.75 mi trail and an ascent of 124 m / 440 ft, it is not the hardest summit around.

We had an appointment for 10 o’clock. The parking lot was still empty at the time, but the weather seemed a bit more difficult than expected. We have asked some other members of our local ham radio club if they want to join us. But surprisingly, no one wanted to get up early on a Saturday morning, hike and operate a radio in freezing temperatures.

As mentioned, the summit was near “Kaltes Feld”, on the opposite side of the valley. You can see the SOTA activation zone of “Kaltes Feld” on the left, the glider airfield in the middle and some miles in the background another SOTA summit called “Stuifen”.

The peak was easy to reach and invites enjoying the beautiful view.

On the actual summit there is a small chapel. Continue reading Pilgrimage to Summits on the Air →

Guest Posts, Hacks and Hints, How To, Morse Code, News, QRP

Bob pairs his ATS-20 with the Zachtek “Flea” CW transmitter

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Many thanks to Bob (K7ZB) who shares the following guest post:

ATS-20 configured with Zachtek “Flea” CW transmitter

The ATS-20 in HF CW Transceiver Mode

by Bob Houf (K7ZB)

I picked up an ATS-20 last summer and played with it on SWBC and the ham bands but found the telescoping whip antenna to be marginal.

The unit I purchased from Amazon turned out to be solid: no problems have surfaced after 9 months of intermittent listening. By default, I have enjoyed it primarily listening to FM in my office.

When I used my long wire antenna, the performance on shortwave greatly improved – easy copy of DX and the value of the receiver began to impress me.

Recently I came across a Swedish ham who co-developed a line of radios covering a broad range of WSPR and associated designs built to a very high standard.

Already having a WSPR setup I was intrigued by a very low power CW transmitter that Zach co-developed with KB9RLW which puts out 300mW on 40, 30 and 20 meters at a price point that is less than the ATS-20, and – most interestingly – the design of the radio allows it to work in transceive mode with the receiver by providing a T/R switch when used with the proper SMA-BNC cable arrangement.

I bought a “Flea” and configured it with my ATS-20 then used an external antenna tuner to make sure the transmitter had close to a 1:1 SWR.  The “Flea” advertises that it is robust to high SWR and looking over the schematic that is evident, but for the sake of a trial I went with the ATU. Continue reading Bob pairs his ATS-20 with the Zachtek “Flea” CW transmitter →

Articles, Field Reports, Guest Posts, Portable, POTA, QRP

“Return-to-Office Policy” triggered POTA activation

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“Return-to-Office Policy” triggered POTA activation

by Thomas (DM1TBE)

I wasn’t sure if I should write a report about this activation. It was “average” at best. But I thought it might be worth to share that not all activations are perfect, with stunning views in an enjoyable environment.

Intro

I am a relatively new ham and completed my first exam in mid-2019. It took me a while to get my head around all the things that the new hobby is offering. My first successful portable activation was in May 2021 on the SOTA summit Michelsberg (DM/BW-855) – here is a picture of my most recent activation some weeks ago:

This first activation was in the middle of the Corona pandemic. The good thing during the Corona time was certainly the possibility to work from home. Before Corona, I did commute roughly 65 km / 40 mi (oneway), which took me in total 2–3 hours daily. During the first two years, I was in the office two times. In the third year, I was there more often, maybe once every two months.

Two weeks ago, my employer announced a “return-to-office” policy, so the “sweet life” was coming to an end.

After the first disappointment, I thought that this may offer me the chance to work portable at new locations. The next SOTA summit is around 20 km / 12 mi away, but a POTA park begins 2 km / 1.2 mi from the office at the pin in the map below. The park is basically all the green wood in the center of the map.

That comes in very handy, as POTA, with the possibility to operate next to my car, does make it easier than hiking in suit and tie to a SOTA summit.

The Nature Park Schönbuch, POTA DA-0008, located southwest of Stuttgart, is a wooded area of 156 km² / 38,000 acres. In 1972 in became the first nature park of the federal State of Baden-Wuerttemberg. The park is an important recreational area for the region.

Image by Cactus26 – Wikimedia Commons – CC BY-SA 3.0

Activation

Right at the beginning of the park, when coming from my office, there is a parking place and next to it a clearing with a fireplace. I thought that this would be a perfect spot for my activities. Weather was cold and windy on my first “return to office” day, I did not expect too many people to be there.

After working and reading the article about the 2023 QSO Today Virtual Ham Expo, I decided to leave the office early at around 4pm and started my activation.

The parking place at the park was pretty empty, just one old car with four lads in it and doing whatever lads are doing in the woods. I have a 16-year-old son and have given up trying to understand what boys at that age are doing.

The spot was OK, but not as perfect as I had thought. It was in a trough surrounded by large trees. In addition, it was wet, cold and windy.

Due to the wind, I have decided against the 10 meter / 33 ft pole and used the PAC-12 again.

The actual activation did not go as smoothly as my previous one. It might have been due to the time, and afternoon during the week, or the topographical conditions. With a small foldable seat and a tiny desk made of a trunk and a brick, I operated for 40 minutes.

In total, I made 16 QSOs; 10 on the 30-meter band and 6 QSOs on 20 meters.

Although I made a successful activation of the Nature Park Schoenbuch, DA-0008, I think I need to change my plans. Being in the office and therefore close to this park more often in the future, I will be more picky in terms of weather and location. The park has way more to offer than a wet and cold meadow in the middle of the woods. I will look for better weather and locations, such as the following – I just need to find those places.

Image by Martin Rathgeber – Wikimedia Commons  – CC BY 2.5
Field Reports, Guest Posts, Morse Code, News, Portable, QRP, SOTA

CQ From Latvia with Love

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CQ From Latvia with Love

by Leo (DL2COM)

A completely under-prepped SOTA & WWFF activation which turned out to be perfect

In preparation for a tough conversation a good friend once told me: “You know what, just walk into the fire. If you have bad news to deliver, don’t sugar coat it and do it right away. You’ll be fine.” 

“Just walk into the fire.” I believe this can be applied to many other situations in life. While I would consider myself to be well-prepared on most trips, hikes and activations and getting a lot of joy out of optimizing my kits I try to stay open-minded. Imagine the things you would miss out on if you wouldn’t be spontaneous or only do things while fully prepared and 100% safe – even if it means taking risks.

On the road back to Riga
The QCX-Mini silently drying after a successful activation

Last Wednesday, I kind of walked into the fire. Not fire as in fire-fire but fire as in Latvian winter storm. In general this wouldn’t be such a big deal had I brought the right clothes, gear and shoes to my short business trip to Riga.

Due to very strict luggage restrictions I could only bring one small backpack for three days. Inside I had enough room for a laptop, washbag, spare clothes and the compact QCX-Mini Kit I built for exactly these occasions. I was wearing sneakers and jeans. At this point I had not planned a specific activation but I wanted at least to be able to operate YL/ & /p maybe 30 minutes from a nearby park – not a problem if you can jump right back into the warm hotel afterwards.

My rental car rocking summer tires in Winter (yes, I was driving veeeeeeery slowly)

During our stay, my schedule for Wednesday morning freed up so I decided to try activating one out of only three SOTA summits in Latvia: YL/YL-003. It turns out this summit is also located within WWFF territory YLFF-0007 about a 1,5h drive from Riga. Big Thanks to Val (YL2SW), Latvia’s WWFF manager, for assisting me with local rules and processing my log. A quick look at the weather forecast showed freezing temperatures, 90% chance of snow, heavy winds and overcast. Many of you will understand why a SOTA&WWFF combo in a rare country could be a small reason not to use the hotel’s sauna on a day like that. Sometimes things just need to get done.

Summit watchtower
The majestic watchtower on YL/YL-003

I got up early the next morning and was very happy to be able to grab a Bolt rental car from the street and get going quickly. The drive went by without issues up to a point just about 3km away from the mountain (well, 1-pointer hill I should say). The roads were completely covered in snow so I could barely see where I was driving. Latvia is a rather flat country but here it started to get a bit hilly and the tires were certainly not cut out for that. Continue reading CQ From Latvia with Love →

Antennas, Comparisons, Guest Posts, News, Portable, POTA, QRP, SOTA

How I found the best antenna for my SOTA/POTA activations

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How I found the best antenna for my SOTA/POTA activations

by Thomas (DM1TBE)

Intro

Until January this year I had a German “Klasse E” / CEPT-novice amateur radio license (equivalent to the US General Class), which limits the use of HF to the 10-,15-, 80- and 160-meter bands. When I started with SOTA I used homemade single band end-fed antennas most of the time. However, that is only feasible for the 10- and 15-meter bands.

Unfortunately, both bands are very moody and sometimes they have not worked at all. Unlike the UK for example, FM is uncommon for SOTA in my home association DM (i.e. Germany Low Mountains). You can be lucky and get your 4 QSOs, but I did not want to rely on pure luck.

Therefore, I bought an end-fed half-wave antenna for 10-, 15-, 20-, 40- and 80-meter bands, after some experiments with 10-80-meter end-fed half-wave antennas, from a small German company called ANjo.

Although I could not use the 20- and 40- meter bands at that time, the EFW80-10P (en: auto-translated) antenna gave me the possibility to use the 80-meter band. The antenna could also be tuned for 15. It has a mechanical length of 23.6 m / 77 ft and a coil for the 80-meter band. It is pretty lightweight with 0.4 kg / 14 oz and allows up to 30 watts PEP – more than enough for me. 80-meters is not the best band for daytime SOTA activations, but in 21 months doing SOTA activations, it worked 37 times and tipped the scales for an activation from time to time.

It was sometimes a bit tricky to raise the long wire into the air, but it always worked … better or worse …somehow … like here in the woods along a trail.

In January this year, I upgraded my license and a new world of HF-bands opened for me. Although I have learned a lot about propagation for the exam, I am in favour of a German saying: “The difference between theory and praxis is larger in the praxis than in the theory”. Continue reading How I found the best antenna for my SOTA/POTA activations →

Articles, Field Reports, Guest Posts, Portable, POTA, QRP

Guest Field Report: Germany has a new POTA activator!

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My conciliation with Parks on the Air

by Thomas (DM1TBE)

Intro

POTA and I had a very one-side relationship so far.

Roughly a year ago I tried to activate a park, but although I spotted myself, I had not been able to make a single QSO. In April last year, I tried it again, with the same result. Luckily, I was on a SOTA summit and spotting me on SOTA brought me enough QSOs to make it a successful activation for both, POTA and SOTA. So I decided to disregard POTA and my only POTA activity was watching Thomas (K4SWL) nice videos on YouTube.

My bad experience with POTA was probably due to two factors:

  1. I only had an intermediate license previously, which limited me on HF to the 10, 15 and 80 meter bands and
  2. POTA was no as popular in Europe and Germany in particular as it was and is in the US. While SOTA and the Flora & Fauna program already had a very active community in Europe for years, POTA had a hen and egg problem.

However, with the increasing popularity of portable operations, POTA has also gained some traction in Europe. I have the feeling that every time I take a look at the spots on the POTA website, I see more European stations.

Things here in Germany have changed for the better, too. POTA got a German website (parksontheair.de) and a community called “Draussenfunker.de” (“Outdoor ham”) with website + Discord that became very active with those pursuing outdoor activities in general and POTA in particular. Lately, local POTA coordinators have been named, who started to add new parks to the program.


Photo by Carsten Steger CC BY-SA

I thought suggesting a recreation area close to my home would be a good idea. A few days later I had the brand new POTA park DA-0410 30 minutes away. The park has a size of 6.3 km² / 1,567 acres and a peak elevation of 780 m / 2559 ft, which is also the SOTA summit Kaltes Feld (DM/BW-659).

My plan was to operate from the clearing on the top plateau, where there is also a mountain hut with restaurant. The 2 km / 1.25 mi trail was not very difficult with an incline of just 105 m / 344ft as the parking area is already at an elevated level.

Although the park extends to the proximity of the parking area at the Hornberg gliding airfield, I wanted to be in the SOTA activation zone due to my bad experiences with POTA activations. The gliding site was founded nearly 100 years ago.  After the First World War, the Allies largely banned motor flight sports in Germany, so gliding airfields, such as this one, popped up across Germany. Continue reading Guest Field Report: Germany has a new POTA activator! →

Articles, Field Reports, Guest Posts, Portable, QRP, SOTA

DM1TBE Field Report: Shivering with 18 WPM on the ruins of the medieval Hohenstaufen Castle

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Many thanks to Thomas (DM1TBE) for the following field report:

Shivering with 18 WPM on the ruins of the medieval Hohenstaufen Castle

by Thomas (DM1TBE)

Intro

It had been two weeks since my last field activation and my bad conscience grew, so a friend and I scheduled an activation, even with expected temperatures at -2 °C / 28 °F. The choice fell on the summit Hohenstaufen (DM/BW-102).

The Hohenstaufen is one of the two SOTA summits that I can see from home in Southern Germany and one of the so-called group Drei Kaiserberge – the middle one does not qualify for SOTA, unfortunately.

A Little Bit of History

On top of the summit are still ruins from the medieval Hohenstaufen Castle. The castle was built around 1050 and used until 1525, when it was looted and burned down during the German Peasants’ War. The summit has been populated since at least the 8th century.

The castle (picture from 1470 above), was the seat of the Hohenstaufen dynasty to whom belonged several Kings and three Emperors of the Holy Roman Empire, which, at its greatest extent, included the area of Germany, Switzerland and parts of France, Austria, Italy, Czech, Belgium, Netherlands, Slovakia – or easier: almost all of Central Europe.

The history of the House of Hohenstaufen was misused by Nazi-Germany when they named the 9th SS Panzer Division Hohenstaufen.

There is not much left of the castle nowadays, but you can still spot parts of the foundations and walls.

Equipment

Due to the positive experiences during the last two activations, I decided to go with an end-fed half-wave antenna for the 30 meter band along with my Elecraft KX3, a 4Ah LiFePo4 battery, a 10 m / 33 ft fibreglass pole and the BaMaKeY TP-III (a 70 g / 2.5 oz light magnetic paddle). The paddle is too light for me to use, so I usually attach the magnetic base of the paddle to a metallic clamp on a clipboard. Although I studied computer science, I prefer pen and paper for logging. Part of the fun is the guessing of the logged call signs after an activation.

Activation

The summit is within walking distance from home, but the weather and a tight family schedule coerced me to drive the 15 minutes to our starting point. Continue reading DM1TBE Field Report: Shivering with 18 WPM on the ruins of the medieval Hohenstaufen Castle →