Category Archives: Guest Posts

Guest Posts, Homebrew, News, Portable, POTA, QRP, QRP Radios

New Summer, New Radio: Field Testing the Thunderbird

15 Comments

by Sam Duwe (WN5C)

I really like homebrew radio. I’m also seeing a pattern: I build through the winter and the spring, get rusty at CW, and then spend the summer operating POTA until my ears bleed. So it’s good to be back! Here’s a quick report of a new radio I built and its maiden voyage.

For the past eight months I have worked on what I call the Thunderbird (v2) named after my local state park, Lake Thunderbird. It’s an 8-band (80-10 meters) 5-watt CW transceiver with SSB receive. I emphasized the latter (decent crystal filter and big speaker/audio amplifier) because while I don’t often use a microphone, listening to voice is both comforting and exciting – I love when the VK and ZL stations drift in late at night. It also works as a somewhat competent general coverage receiver for short wave listening. I built it to operate both in the shack and on a picnic table, it unfortunately is a bit heavy because I got greedy and kept adding bands.

I guess I “designed” this radio, but as I discussed before on this site I’m just a guy with no engineering background who learned to solder and read a schematic diagram. But by doing so I could understand and modify the clever circuits from the radios we love and then figure out how to make them play nicely together.

I built the radio using Manhattan construction on copper boards, and then stacked these and fit them into a metal project box with 3D printed front and rear panels. It’s a bit fiddly and messy, but I feel like I’m ready to challenge my family to a game of Operation! The nice thing about stacking the boards is that I can shield the receiver from the transmitter and digital components.

The bottom board houses the band-pass filters, receiver, and audio chain. This was my first attempt at building a superheterodyne receiver so I was a bit nervous (although this video calmed me down). The receiver takes inspiration from John Dillon’s (WA3RNC) TR-35. He uses a clever design to narrow (for CW) and widen (for SBB) the crystal filter. I also cribbed his excellent idea for the LED signal-strength meter. The audio chain was modified from the Elecraft KX1 which includes an AGC circuit. I learned last summer how important AGC is when I was on Vail Pass in Colorado and actually fell out of my chair and groaned in pain when a guy with an amp called me back. I also hand built an NM0S Hi-Per-Mite to switch in when I want a steep 200-Hz filter. This is an awesome circuit that you can buy in kit form.

Like I mentioned, I got greedy and experienced project creep. Honestly, I would have been super happy with 40, 30, and 20 meters, and 17 would be nice. But so would 15, and 10, and even 12 (a band that I only have a handful of contacts on ever). And why not 80 meters? So I modified Steve Weber’s (KD1JV) Tri-Bander relay-switched band-pass filter design to add them all. I also figured out how to build a preamp for the high bands. I built a secondary audio amp to drive a 3-inch 3-watt 8-ohm speaker for annoying my family at night.

The lower board with the receiver, band-pass filter board, and audio chain.

The top board houses the transmitter and the digital components. The transmitter is based on Steve Weber’s design because it’s perfect and is used in some form by many QRP CW rigs. It gives me between 4-6 watts output on all bands. Like with the receiver, I used his design for the low-pass filter board.

The heart of the transceiver is an Arduino/si5351 combination and the Arduino code written by Paul Taylor (VK3HN). Besides doing the heavy lifting of aiding me pull audio out of the ether his code and associated circuits are versatile and clever, including automatic filter switching, CW messages, and both keyer and straight key support.

Although I am mildly terrified of AI, ChatGPT helped me add all kinds of bells and whistles (on my own I’m not a very good programmer) such as RIT, audio filter switching, keyer speed control, and a simple but detailed display that shows the relevant information. The panel controls are all knobs and switches.

The upper board with the transmitter, low-pass filter board, and digital components.

Between the sub-par band conditions as of late, and my neighborhood’s increasingly nightmarish RFI, testing the radio’s real-world performance was difficult. Luckily I have an IC-703 on the bench and it keeps me sane. The Thunderbird isn’t as good but it’s maybe 85% of the way there (when I turn off the DSP and noise blanker on the Icom)? It has been disconcerting when 10-meter FT8 isn’t coming through, but apparently that’s the sun’s fault and not mine. But this radio was built for POTA, so onwards to my park!

For an activation it was a rush job. I had just finished with the fixing a few loose connections when I realized I had about an hour of time before picking my kid up from camp. So I headed to the park with the radio, my favorite easy-to-deploy antenna [QRPer affiliate link], and my ATU-10 (doubles both as a tuner and check to see if the radio actually works).

There has been a lot of rain here lately so my usual spot was underwater. As I was setting up on the high ground a car drove past me multiple times. I figured I was either in trouble or it was a ham, and fortunately it was the latter. Larry (WA5NTF) and I had a nice chat and he graciously drove across the bay to absolutely clean up on digital. For me, I spent about 30 minutes on 20-meters, got 25 contacts, and then failed on the high bands. This is my first solar-cycle peak: get it in gear, Sun.

A few observations: I really liked the speaker! I was away from others and could use it without invoking ire, and it was freeing. Same with the message function which helped because it wasn’t a day of pileups. I also am so used to an S6 noise level on 20-meter SSB that when I first started the radio I assumed it was broken, so quiet. What a difference being out of the city makes.

But it worked! I have some trips planned for the summer and fall to the Southwest so I can’t wait to lug this box to some weird places. And I’ll hopefully be operating locally quite a bit more. Hope to hear you on the air, hopefully on the high bands!

And a postscript, I’m not going to be a homebrew proselytizer, but if you have an inkling to try something new a great project is the SolderSmoke direct conversion receiver (I started with something similar). On this page there is a link to their active Discord server with friendly people and lots of guides on how to hand build a 40-meter receiver. Paired with a simple transmitter it would make POTA (even more) ridiculously fun.

72, Sam

Guest Posts, News

QRPer Discussion Board: Three Years of Community and Collaboration

4 Comments

Three Years of the QRPer Discussion Board

by QRPer.net Admin

Purpose

Many of us who regularly visit the QRPer.com Web Log really enjoy the content created and curated here by Thomas Witherspoon, K4SWL.  His unassuming style, broad knowledge, and humility have encouraged trust and loyalty among his followers.  Many of us openly defy the YouTube algorithm to follow his real time, real life, activation videos.  We have come to rely on the knowledge he shares in his thorough and comprehensive reviews of new equipment.  We also value his thoughtful and encouraging response to our burning questions.  In short, Thomas’s followers can happily consume as much time as he is willing to devote to meeting our needs, and we have him greatly outnumbered!

The QRPer.net Discussion Board was conceived as a means to ease Thomas’s burden by empowering the QRPer community to crowd-source answers to detailed questions, to provide a forum for discussion among QRP and Field Operating enthusiasts, and to educate and encourage newer operators.  Selfishly, it was hoped that this community involvement would enable Thomas to use his limited time to create more of the unique content that we all crave.

Three years ago, this free resource came into being.  Not only did it serve the desired purpose, but it also built a library of information gained through discussion, answers to questions, sharing opinions, and generally fostering enthusiasm and shared passion among the community.  Oh, and as a bonus, existing posts on the QRPer Discussion Board are searchable, making it fast and easy to find posted comments that match your question or your interest!

Growing Pains

To date there are over 800 members, some of whom have contributed to the almost 1400 posted comments related to QRP and field operation.  A group of volunteers moderates posted content (active moderation is rarely required, because Thomas’s followers are a well-mannered and courteous group).  Until mid-2024, setting up an account was simple and easy, but then our community was discovered and targeted by spammers.

We have tried a number of methods to keep spammers out, because spam accounts started posting off-topic, and objectionable content.  First we applied the hosting software’s automated anti-spambot countermeasures, basically a maze that a new user needed to navigate before creating an account.  This worked to a point, but spambots quickly found a path through the maze to create hundreds of new accounts per week.  So, now we require a correct answer to a QRP- or Amateur Radio-related question, changing the questions as the spambots catch on.  We also manually validate each new account before the owner is allowed to post to the Discussion Board.  This validation relies on 2-factors for authentication.

Validating New Accounts

Preferably account creators are validated because they also sent an email containing their account username, the email address that they used to create the account, and their amateur radio callsign (or “Short Wave Listener” if not licensed) to qrpernet@gmail.com.  When such an email is received for a newly created account, that account is activated for use.  This email requirement is only advertised on the QRPer.com Web Log, and spambots have not yet discovered this connection.

Often new accounts arrive without an email.  When this happens, your humble Admin looks at the username and email address for the new account.  If an amateur callsign can be discovered in either, it is manually looked up on QRZ.com.  When the email address of record on QRZ.com matches the email associated with the new account, the account is considered valid and it is activated.  When the QRZ.com page reports a different email address, it really slows down the process.  When time permits, an “Admin Email” from qrpernet@gmail.com may be sent to the QRZ email address of record, asking whether the licensee created the new account.  Frequently this does not elicit a response, likely because the Admin Email itself is deleted as spam.

Many times the licensee’s QRZ page does not report an email address, so validated communication is not possible.  These accounts are kept on the pending accounts list for a few weeks awaiting a confirmation email, but are then deleted when the pending accounts list grows to the point of becoming unmanageable.

Admin Email is not sent to the (unconfirmed) email addresses associated with new accounts, because that could be further exploited by the spammers.  Finally, accounts are not activated just based on their reference to a valid Amateur Radio callsign, because it is too easy to pirate callsign information and pair it with a bogus email address.

If you have had difficulty getting an account activated on the QRPer Discussion Board, you have my sincere apology.  Please try again, and send an email to qrpernet@gmail.com to speed validation.  Your Admin (who is not Thomas) chooses to remain anonymous to avoid any personal interaction with spammers and spambots.  Your patience is sincerely appreciated, because in the end, one volunteer from your community is handling the validation and activation process.  So far, the spammers have not found a way around these controls, but likely that is just a matter of time.

Conclusion

So there you have it!  It would be great to have all interested QRPers join and actively participate in the Discussion Board community.  You now know the potential benefits, you understand the challenges we face, and you understand how to get your own account activated quickly.  I hope to see your posts soon on the QRPer Discussion Board!

72,

Admin

Accessories, Guest Posts, Hacks and Hints, News, POTA, SOTA

How “No Fly Zone” Clothing Changed My POTA Activations

7 Comments

By Conrad Trautmann (N2YCH)

QRPer.com is a great resource for all of us field activators. Thomas (K4SWL) posts about all kinds of nifty tools and things to help us while doing our field activations. He recently posted a story about Red Oxx bags (I think I need one), also a recent post about insect repellents,  which made me wonder if he’d consider a guest post about “No Fly Zone” clothing. These are clothes made of insect repellent treated fabric. I asked, Thomas said yes, so here’s my story…

A few years ago, I decided to try and activate all of the parks in the State of Connecticut. During my quest, I was out in the parks a lot…often coming home complaining of bug bites, and covered with and smelling of Deep Woods Off bug spray. If there are 100 people in a room with me and one mosquito, it will find and bite me first. I simply attract any flying, biting insect. I’m a bug magnet. I just accepted the fact that getting bit up and dousing myself in bug spray was going to be part of my quest.

Then, my very supportive XYL, Dianne, decided to gift me two shirts from LLBean’s “No Fly Zone” collection. That was a game changer. These shirts work. Bugs hate them. The shirts are long sleeve to cover your arms with a collar that can be turned up and used to cover up your neck.

Conrad, N2YCH wearing an LLBean No Fly Zone shirt and Peter, K1PCN at POTA park US-1815, Little Beaver State Park in West Virginia

My first outing with one of these shirts was amazing. I called my wife from the park to tell her that the mosquitos were leaving me alone, except for my head. I said, “I wish these guys made a hat out of this material.”

Voilà, Dianne found me a hat, too!

Conrad, N2YCH, wearing an LLBean No Fly Zone hat and shirt at POTA US-1716, Silver Sands State Park in Connecticut

The web site for Burlington Fabrics, the company who manufactures the fabric, says this:

“No Fly Zone® Insect Repellent Technology is a permethrin-based technology that converts gear and garments into long- lasting, effective, and convenient insect protection.

The main ingredient, permethrin, is a man-made, contact insecticide, structurally similar to a naturally occurring chemical derived from the dried flowers of the Crysanthemum.”

The web site claims it will remain effective for 70 washes. So far, mine are still working just fine after a few years. Seeing how effective these clothes have been, Dianne has gotten me more shirts to add to my collection, including some short and long sleeve Tee’s and even a pair of socks.

Connecticut is home to the town Lyme disease was named for and we do have ticks here. I’ve been bitten once, thankfully not by one with Lyme disease. To combat this, I wear the LLBean insect repellent socks along with Merrill Moab 3 boots to discourage them from jumping up on me. Recently, I discovered that Columbia Sportswear makes “Insect Shield” clothing, including pants. I bought a pair of their Cargo pants and they worked great paired with my LLBean socks, shirts and hat.

Conrad, N2YCH wearing Columbia Insect Shield Cargo pants, Merrill hiking boots and a light gray LLBean No Fly Zone long sleeve T-shirt. With Peter, K1PCN at POTA US-0020, Cuyahoga Valley National Park.

One nice thing about the Columbia pants is that they have an adjustable elastic drawstring at the ankle cuff that you can pull tight to keep critters out. Insect Shield’s home page says that their fabric is also treated with permethrin. On a recent POTA outing on our way to the Dayton Hamvention, I was completely left alone by the hoards of flying insects at US-1815, Little Beaver State Park in West Virginia. No bug spray necessary.

Conrad, N2YCH wearing a gold LLBean No Fly Zone long sleeve T-shirt with the Connecticut POTA Activators Support Your Park Spring gathering at POTA US-1728, Wharton Brook State Park in Connecticut

Activated all Connecticut Parks

Thanks to my wonderful and supportive XYL who supports my hobby (and probably enjoys the peace and quiet when I’m off doing POTA), I did finally get to and activate all 150 parks here in Connecticut, most of them while wearing my No Fly Zone shirts and hat. They really work and I recommend them for a bug free activation.

Field Reports, Guest Posts, News, POTA, QRP, SSB

James’ first POTA activation with the IC-705

13 Comments

Many thanks to James (KI5OEB) who shares the following field report:

My First POTA Activation with a New Radio

by James (KI5OEB)

I decided, thanks to the influence of many people, mainly Thomas K4SWL and Steve KM9G, to purchase my first-ever new transceiver. I purchased an ICOM IC-705 from a retailer that had an open box item for sale. This was just before the 2025 Dayton Hamvention, when the new Yaesu FTX-1F was to be premiered. Many hours of evaluating specifications and performance numbers went into my decision, with a bit of influence from other videos as well. Most of the video footage that is available is actually from four years ago when this radio was first released.

Before going into the field, I unboxed the transceiver and made a few clicks on the new transceiver. I charged the attached battery during the week prior to use. A few other things I did were to prep an Apache Case and make sure I had the appropriate external batteries. I wanted to be ready to take this out for a successful first park activation.

Last Saturday, Memorial Day Weekend, I had some free time at about noon to go to a park, POTA US-7687 Drummond Flats Wildlife Management Area, to give this radio its maiden activation. It takes less than 20 minutes to drive there from my house, so this is my second most frequent location for activating. The site is a zero noise floor site on any band, which I have observed in the past, and today was no different.

Some quick history, I have a few years under my belt using both ICOM and Yaesu transceivers. I still ask others about things, but I can usually figure it out if given enough time. I have regularly used IC-7600, IC-7100, IC-706 MKIIG and IC-703+ transceivers with success. My standard antenna setups are 40m-10m EFHW from Coffee and Ham Radios with a 10m mast for a sloper configuration, 17’ Chameleon Whip on a Spike, and if I’m going to be activating for a longer time I use a DX Commander Classic 40m – 10m.

Today was only going to be a short, 1 to 3 hour activation, giving plenty of time for the QRP Single Side Band propagation to get out and be heard, much like I have done with the IC-703+ in the past. I set up the CHA-17 on the spike like normal, driving the 18” spike into the hard dirt with a hatchet from the truck. Nothing difficult, just spread out the nine radials on two crimped alligator clips, raise the mast for 17m to start, connect the RG-8x, and I was ready.

Next, I hooked up the external battery to the new transceiver, but wait, I need to make sure the nanoVNA has the perfect tune for 17m. Let me think, the IC-705 has an SWR sweep function like the IC-7100, let’s try that first and see. Bam, first try I was near 1:1 throughout the entire 17m band.

I placed the microphone and transceiver on the table where I’m set up and ready to go. Opened the screen to start the logging software on the laptop. Opened my phone to the POTA APP and self-spotted. I’m ready, but I’m not. In the 10 minutes it took to set up all the things I wanted to use, I got warm in the midday sun. So, I put the tailgate down, slid the canopy out, and proceeded to put up my 10×10 Sun shade, to include 16” nail spikes on each corner for the wind. Placed the beverage tote next to my chair, and now I was ready.

I turned the transceiver back on and listened. Okay I don’t know how to really run this new gadget, but it probably needs AF gain and RF gain, that is the same knob on this radio. Yes, they were nearly zero; now, with a flick of the knob, they are at 60% each. I am concerned that the waterfall is not showing signals. Well, it was learn as you go day here in the park, but the gain being raised made a difference on the waterfall, too. I saw a few faint signals; this will be okay. I hit the center/fix button and have the entire 17m band in view. Looking at the POTA APP, there are only two stations besides me on the band.

I zeroed in on an open spot that wasn’t being occupied and listened for about a minute. I asked a few times, like I’m supposed to, to find if the frequency was in use, but I heard nothing. Spotted that frequency, and we are off. I called CQ for over five minutes, and no reply. Then, I got two contacts back-to-back! Cool! This is going to be easy. Nope, someone moved in 1k below me and made it impossible. I moved up 3k and listened. Spotted on The POTA APP and started calling. Then, I get a few more contacts, and another intruder moved in above me this time by 2k. So I moved down 7k, to complete my activation. Frustrated a bit, but i now had 10 contacts and that was an activation.

So, I decided to move into the 20m space and hunt there for a bit. Went and extended the 17’ whip and got back to the radio to verify. I did something wrong on the screen, so no worries, I still have the nanoVNA handy, and Bam SWR near 1:1 again this time on the 20m band.

I was ready to hunt now. I did a little fiddling with the screen to let me see the Center instead of the fixed view from 17m. 20m band is packed with signals from 14.225 MHz through the top of the band edge at 14.350 MHz. This should be easy, but I’m hunting QRP!

After zero contacts, I wound up selecting a frequency between two QRO stations and parked on 14.291 MHz. I managed to make quite a few contacts here for the next 30 minutes. Great fun, and I had an ‘almost’ pile-up. Then, for 15 minutes, I used the spots page to find other stations.

In the end, I had made 38 contacts in two hours and twenty minutes. The real takeaway, though, was a realization that this is the finest receiver I have ever used. Through the front-firing speaker, I heard stations that I know no other radio in my collection would receive. I had to adjust my AF gain many times due to the fact that a 100-watt station sounded like they were sitting next to me, yelling. Then, I would hear a whisper, turn up the gain, and talk to a station in the Upper Peninsula of Michigan from Oklahoma, that is a big ask for 10 watts. In those 38 contacts, I was amazed, learning new things about the technology that allows a serious communication jump. This only took 38 contacts and a little over two hours.

If I am asked which transceiver I recommend to an amateur operator, I can’t say any other transceiver than the IC-705. This was a huge eye-opener for me. I hope other people in our hobby/service get the opportunity to use such modern equipment. Please, folks, take the time in the near future to peel the plastic off something new or at least go to a retailer or hamfest to try something new!

James Popham KI5OEB

Field Radio Kits, Guest Posts, Kits, News, Portable, POTA, QRP, QRP Radios, SOTA, Videos

A Strong Case for the (tr)uSDX: Jamie’s Perspective

17 Comments

Readers, there’s a bit of a backstory to this guest post by my friend Jamie (AA4K). During the W4SOTA campout in October 2023, Jamie showed me his favorite field radio: the (tr)uSDX. I’ve used the (tr)uSDX for a couple of activations, but I’ll be honest—I haven’t exactly shown it a lot of love. I’ve even complained about its audio and receiver performance in the past. Jamie, on the other hand, really enjoys using his and makes a solid case for it as a field radio.

Jamie showing me his (tr)uSDX during the W4SOTA campout.

I asked if he’d be willing to write a guest post for QRPer, and he agreed (eventually!). When I saw him at Hamvention this year, he told me the article was ready—and in true form, he sent it to me via Winlink… using his (tr)uSDX.

A Case for the (tr)USDX

by Jamie (AA4K)

Introduction

There are many factors that must be considered when choosing a field radio. How big and heavy is the radio? How hard is it to repair or replace the radio if it becomes damaged or lost? How hard is the radio to operate? How power-efficient is the radio? Does the radio have the desired/required modes and features? Of course, the most fundamental question is, “Does the radio work?” I will try to answer these questions as I lay out… a case for the (tr)USDX as perhaps an almost perfect field radio.

The last two contacts on this page were with my friends Carlos (KB4CO, now AE2W) and Thomas (K4SWL).

How big and heavy is it?

The first question is an easy one. Aside from small home-brew radios such as K6ARK’s “Choking Hazard”, there isn’t a smaller or lighter commercially available radio out there that I am aware of. The (tr)USDX measures 112 x 61 x 50 mm (I trimmed the encoder post and used a lower profile knob), and weighs 5.3 oz, or 151 g. The next closest currently available commercial radio is perhaps the QRP Labs QMX. This radio is very comparable in size (110 x 64 x 38 mm) and cost, but it does weigh more at 7.3 oz, or 207 g. The more rugged metal case probably plays a big part in the weight difference.

(tr)USDX with a modified case I designed to use the radio as the antenna winder.

How hard is it to replace or repair it?

The (tr)USDX is often sold as a kit for about US$86 (+$20 for the case) [QRPer affiliate links]. Any repairs should simply involve desoldering affected components and replacing, or possibly just updating the firmware. I am a relative noob when it comes to kit building and this kit is honestly not very difficult to build… about one day. The instructions and support videos provided by the hardware developer, Manuel DL2MAN, are very thorough. I learned a lot about radios from building the kit. If you have no interest in kit building, the assembled radio can currently be purchased from Amazon for US$138, complete with a case. Whether purchased as a kit, or already built, the band pass filters on the radio board will need to be tweaked to get the most out of your radio.

How hard is it to operate?

The (tr)USDX only has 4 buttons including the rotary encoder: Menu, Encoder, Enter, and PTT. The Menu and Encoder cover the majority of the adjustments, and most of the time I don’t use the Enter and PTT buttons. The PTT functions only as a ptt or cw key depending on the mode (yes, if your key breaks mid activation, you have a built-in backup key). The single-layer menu system is simple to scroll through, and the most commonly used items are near the front of the menu.

The most challenging aspect of operation for some people is the tiny OLED screen which gets obliterated in bright light. Reading glasses do help, although when you become familiar with the menu are not as important. I would love to see a version with an e-ink display and, more importantly, a push-button wheel rotary encoder (to remove the protruding knob).

How power-efficient is it?

This radio sips power. I tested the radio I built using a LiFePO4 battery that supplied 13.56v. The current draw on receive is 66.1 mA, and 570 mA on CW keydown into a dummy load. A properly tuned (tr)USDX delivers about 5w on each of the five bands when fed ~12v. A set of three 18650s in series will provide the proper voltage and power the radio through many activations.

Does the radio have the desired/required modes and features?

The (tr)USDX is not for princesses. It is a minimalist’s radio. But if you start from the perspective of an ultralight backpacker who has to justify every gram in their kit, this radio checks all of the boxes. It is a five band radio (Low, Classic, and High band models available). It is capable of doing voice, cw and digital modes. Thanks to a beta update from the firmware developer, Guido PE1NNZ, this radio will interface with a computer without requiring a soundcard. One of my favorite features of the radio is the built-in SWR meter. With the SWR feature enabled in the menu, just put the radio in CW mode and press the PTT to find out if your radio is happy with the current antenna arrangement.

This photo was taken while sending the text of this article via Winlink to Thomas, K4SWL.

Does the radio work?

Although my total activation count is nowhere near as high as many of you, I have used the (tr)USDX for a majority of my successful POTA (156 as of this writing) and SOTA (72 as of this writing) activations. My confidence in this little radio was demonstrated when I used it on an ATNO activation of Admiralty Island National Monument (US-4537) in Alaska.

Conclusion

One reason why I like to participate in SOTA and POTA is that it gives me an opportunity to practice field radio deployment and operation with the goal of being ready to communicate anywhere and anytime. This level of readiness means that I have the necessary equipment with me all the time. For me, the (tr)USDX is my EDC (every day carry) radio. It can bounce around in my backpack (in its protective case, of course) and be ready to deploy if needed. If it were to get lost or broken, I can fix or replace it easily. And I find it to be easy enough to use with the understanding that it isn’t a luxury radio.

The author at ~11,000’ in Uncompahgre National Forest.

Video

Click here to view on YouTube.

(tr)uSDX Winder Case:

Click here to download the print file for Jamie’s the modified (tr)uSDX case.

Antennas, Guest Posts, How To, News, Portable, POTA, QRP, SOTA

Build a Linked End-Fed Half-Wave Antenna with Bluetooth-Remote Band Switching!

20 Comments

A Remote Control Antenna Link

by Dave (KO4YLZ)

Like so many other SOTA activators, I’m constantly tweaking my gear to optimize it for all the variables we encounter in the mountains. One of my main antennas is, of course, an EFHW. Paired with my KX2, I generally get sub-1.6:1 SWR on 40, 20, 15, and 10. However, 30m has an unacceptably high SWR. I considered switching to a multi-link EFHW, but hopping up to change links to chase an inadvertent S2S on another band is inconvenient, especially when the link for low bands is generally well beyond my reach and requires lowering the antenna.

To fully optimize my EFHW I decided I needed to come up with a way to add a “remote” link for 30m. After a couple of design iterations, I came up with the light-weight and compact remote antenna link shown/described below. The version described here is not my final one. While this “pill bottle” version is still quite small, I’d like to reduce the size even further.

Let’s start with the end…

Here’s the final product. It weighs under 1 oz. and is ~2.5” long. I have included a complete parts list at the end of the article.

My design considerations were:

  • Small and light
  • Range of at least 75 ft.
  • Reasonable battery life
  • Waterproof
  • Durable
  • Able to withstand the current at the 30m position on the antenna
  • Doesn’t adversely impact antenna performance on other bands
  • Easy to connect and disconnect from the antenna

Executive Summary

For those in a hurry, here’s a summary description of the remote antenna link. It consists of a very, very small remote control Bluetooth relay powered by two CR2032 batteries (user supplied). A set of contacts (either normally open or closed) lead from the relay to male and female 2mm bullet banana connectors in the cap of the pill bottle. Two matching bullet banana connectors at the antenna plug into the remote control link.

To operate, you simply open the bottle, switch on the batteries, re-install the cap, extend the antenna, and plug the bullet banana connectors at the antenna into the opposite pair embedded in the cap of the pill bottle. When you are ready to operate, you just push the remote button. When the remote button is pushed, the relay opens or closes thereby making or breaking the link and physically shortening or lengthening the antenna. Below is a picture of both sides of the mini-relay (antenna wire not shown)

The relay can run on 3.5-12 volts and can handle 1A. The included 1-button transmitter sends a signal (455mHz) to the relay and either opens or closes a set of contacts depending on how the user programs the relay.

Wiring It Up

I won’t bore you with a detailed written explanation…it’s a pretty simple build. Below are a simple wiring diagram and a series of photos with build details [click images to enlarge].

Making It work

The relay has three operating modes: latched, momentary, and toggle. Because I wanted the 30m link to be normally connected when the relay is in standby waiting for a signal from the remote control and open and stay open when I pressed the remote button, I had to reprogram the relay. Programming is accomplished by turning the unit on, then putting a 22ga wire jumper between the two “programming dots” and then pressing the remote button until the LED on the relay board flashes the number of times specified in the instructions for the operating mode you want.  The instructions are not very clear, so I recommend connecting the unit to your VOM in continuity mode to figure out the button/LED flashing sequence that corresponds to how you want the relay to behave.

Testing

The unit is rated for 1A so, to be sure I wasn’t going to blow it up when I transmitted with 10 watts, I used ChatGPT to produce a very nice graph showing the current at the 30m position on the antenna for each band when transmitting with 10W. Here’s the graph. Luckily, the maximum current at the 30m position (~43’) is .6A at 7.062 MHz.

I tested the unit on my KX2 by setting my operating frequency and then putting the KX2 tuner in bypass mode and pressing the button on the remote control; Ding…the SWR jumped immediately to the expected pre-determined (and acceptable) SWR value for the 30m band!

The unit draws 7mA when in standby and 32mA when the relay is energized. Assuming 40 minutes of operating off of the 30m band (relay not energized) and 20 minutes on the 30m band (relay energized), I calculated that approximately 17mA would be drawn from the two CR2032 batteries. Given that a CR2032 battery has a capacity of 220mAh, they should provide about 12 hours of operation.

Any questions, please comment.
Dave – KO4YLZ

Parts List

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

A relaxing activation at Fort Harrison State Park

1 Comment

by Vince (VE6LK)

As always there are lots of links within the article. Click one! Click them all! Learn all the things! ?

Dear readers, Hamvention 2025 was a wonderful getaway for me, and I met so many people in 3-D that I’d only ever worked with over teleconferencing. It was super great to see members of the Ham Radio Workbench Podcast crew (and friends of…) and get to hang with them for several days. Naturally, this included QRPer.com host Thomas K4SWL.

I was the last of the group to leave the Dayton area on May 20th and I began my drive back to the Indianapolis airport for the first of two flights home. And, naturally, this means a POTA stop along the way, and it would be my first in Indiana. While I had grand plans to visit WV and KY along the way, those plans fell by the wayside for a simpler and direct route from Dayton to Indianapolis.

When I travel like this, I look for parks that appear to be radio quiet and are not too far off the path of travel. Fort Harrison State Park was my chosen destination. And it did not disappoint in any way at all.  Located in the NW corner of the Greater Indianapolis area, it is 1,700 acres of recreation nestled in a small quiet valley just away from the hustle and bustle of everyday life. Homes outside the park entrance seem to be from an era of yesteryear. I wished I would have had more time to explore!

Arriving at the park and one of the many picnic areas, I chose to be beside the lake. It was raining quite hard until up when I arrived and then let up to an intermittent drizzle. Fortunately there was a picnic shelter and a washroom building within eyesight. Accordingly I set up in the shelter with my KX3, Charmast battery and VK3IL pressure paddle.

I put out my Gigaparts Explorer 20 mast and new-to-me Packtenna 20m EFHW along with my fishing rod holder ground spike, hit tune on the KX3 and got to work.

The contacts didn’t come fast and furious, as the past week or so the SSN, SFI, A and K indicies weren’t really in my favour. Many times I would answer a station and they’d simply disappear. It took 30 minutes on air to complete the activation. This was a stark improvement from the day prior where it took well over an hour.

RBN Screengrab from the video

The Reverse Beacon Network told me my 10W signal was being heard all over the USA and some in Alberta Canada also, despite it putting my outgoing dot (see image above) on Montana where my USA callsign is based.

Denver airport where this article was written – and this is quiet!

Still, after the extreme hustle and bustle of the days prior, this was super relaxing and just the break I needed before dealing with airports, rental cars and plenty of other travellers.

Having spent so much time around K4SWL, I channelled his video style and did an end to end on the activation without any edits – you can see that video on YT.

Click here to view on YouTube.

List of gear used for these activations:

Summary

Sometimes it’s just great to find a place to hang out in the peace and quiet, and this park was perfect and just what I needed after many days of constantly running.

72 and dit dit,
…Vince

First introduced to the magic of radio by a family member in 1969, Vince has been active in the hobby since 2002. He is an Accredited examiner in Canada and the USA, operates on almost all of the modes, and is continually working on making his CW proficiency suck less. He participates in public service events around Western Canada and is active on the air while glamping, mobile, at home or doing a POTA activation. You can hear him on the Ham Radio Workbench podcast, follow him on Twitter @VE6LK, check out his YouTube channel, and view the projects and articles on his website.

Field Reports, Guest Posts, News, Portable, POTA, QRP, QRP Radios, Reviews

The POTA Babe Tries the CFT1

24 Comments
By Teri KO4WFP

Jonathan KM4CFT reached out to me recently to inquire if I was interested in trying his CFT1 QRP transceiver. The inquiry both surprised and delighted me as I’ve never had such an opportunity.

I nearly said no because I am no antenna expert and, as this rig has no internal antenna tuner, I’d need to learn more about antennas, SWR, and resonance.

My limited antenna experience dates back to when I first entered the hobby. I had ZERO antennas and no idea where to start. An acquaintance suggested I make a home-brew linked dipole and gave me a few pointers in doing so. I vividly remember limping through learning how to trim an antenna. That project taught me that I want as low a SWR as possible and to cut the antenna for the portion of the band on which I want to operate.

homebrew linked dipole

Those of you who read my articles here on QRPer know that I use an Elecraft KX2 for my field operations. I’m very happy with this radio and love that it has an internal antenna tuner. But the CTF1 does not. Here is where my hesitation and trepidation at trying this unit entered the picture. I figured the antennas I use on a regular basis might not play nice with the CFT1 and hence my reluctance to say “yes” to this opportunity.

“Craig”, my KX2

But this is ham radio, right? In ham radio, we relish challenges because they are opportunities to learn. This was my opportunity to learn not only about antennas in general but also to be more thoughtful as to how I deploy them in the field. This was an opportunity for growth.

I dug out the RigExpert Stick antenna analyzer I purchased nearly three years ago and tested each of the antennas I currently have, just for jollies. I understand that many factors impact SWR – height of the antenna, coax length, proximity of other objects, etc. For the purpose of this exercise, I just wanted a ball park idea as to what antennas I could or could not use with this rig without a tuner.

I found both the home-brew linked dipole and the Chelegance MC-750 would work fine. Out were the EFRW and AX1. As I’d been hankering for an EFHW in my kit, I purchased the Sparkplug EFHW and trimmed it. These kinds of projects intimidate me because I do not have much experience with them; however, one cannot learn what one does not attempt.

I used the CFT1 on three activations: April 25th at the Savannah National Wildlife Refuge (NWR) (US-0522) with the Chelegance MC-750, April 30th at the refuge again but this time with the Sparkplug EFHW, and Thursday, May 1st at George L. Smith State Park (US-2179) with the Chelegance again.

It was a warm day at the refuge on April 25th. I selected an open area in which I had set up in the past. There were wild blackberries growing directly under the oaks in the shade. The view was lovely and, when not engaged with the activation, the red-wing blackbirds, coots, and other birds kept me entertained. Unfortunately for me, the sun moved out behind the oak trees not long after I arrived and I soon called QRT to avoid being baked.

the field in which I set up
wild blackberries
cooter out sunning itself
water lillies in the impoundments
what is not to love about that view!?

I was pleased with the QSO map for this activation – 27 contacts on 40, 20, and 17 meters over the course of an hour and a half.

QSO Map for Savannah NWR 4-25-2025    Source: qsomap.com

My second experience with the CFT1 was on April 30th, again at the Savannah NWR, however, this time using the Sparkplug EFHW. I found a different spot, one I passed up before but was usable today as it was freshly mowed. There were wonderful, tall oak trees at this location which afforded shade and high, unencumbered branches for installing an antenna aloft. Continue reading The POTA Babe Tries the CFT1 →

Field Reports, Guest Posts, News, Portable, POTA, QRP, Travel

Activating on the Road:  The Last Park

4 Comments

by Brian (K3ES)

In case you haven’t seen previous Field Reports in this series, let me set the stage.  In September and October of 2024, my wife, Becky, and I set out with our dog, Molly, for a great cross-country driving adventure.

We left from our home in northwest Pennsylvania on September 18, driving west to spend some time with my parents at their home in California’s Bay Area.  We returned home on October 31, after driving through most of the states of the American West.  One of the goals for this trip was to activate Parks on the Air (POTA) entities in as many new states as possible along the way (it turns out that with good planning and good weather, it is possible to activate a LOT of states).  An overview of our trip can be found in the following Field Report (linked) on QRPer.com:  Six Weeks and 7300 Miles:  Activating on the Road.

On the westward leg of our trip, we zipped through Ohio and Indiana in a single marathon day of driving, without stopping to activate a park.  There was no intent to diminish these fine states of our union, but I had previously activated parks there.

On the return leg of the trip, our priorities and our perspectives had changed a bit, so we made up for our previous inattention by activating new parks in both states on the way home.  The change in priority came with the realization that we had succeeded in activating every state that I had planned to complete.  I have now activated every lower 48 state west of the Mississippi River, save Arkansas and Louisiana (we intentionally left them for a future trip through the southern states).  The change in perspective came from the realization that activating a park made for a nice break during a day of driving.

We planned for a modest 3-1/2 hour drive on our final day of the trip, so that we could arrive home before dark.

We spent the night near Mansfield, OH, and took our time getting breakfast and checking out in the morning.  We had also looked over our maps and found an Ohio park to activate during the drive:  Lake Milton State Park, US-3515.

Lake Milton State Park

Seen from the park, this bridge carries Interstate 76 across Lake Milton

As I-76 runs east-to-west across northern Ohio, it crosses over the middle of Lake Milton.  For radio amateurs familiar with other attractions along the I-76 corridor, Lake Milton is about 20 miles east of the DX Engineering store.

Lake Milton State Park incorporates the lake itself, as well as selected land around the lake-shore.    We decided to head for one of the park’s picnic areas, located on the eastern shore of the lake near the I-76 bridge.  We found a parking lot, a large grassy area running down to the lake, picnic shelters, and comfort facilities.  As Becky took Molly for a walk around the grounds, I set up to operate from a table in a picnic shelter.

A view of the picnic area beside Lake Milton shows me activating from the shelter at left.  I threw a line over a branch on the tree to the right, and used it to hold my antenna as a sloper.
The gull in this picture was riding the wind, but going nowhere fast.
Standing straight out from its flagpole, this flag spoke eloquently of the wind.

It was a nice afternoon at the park.  The weather was warm and sunny, but a stiff breeze was blowing across the lake.  An American flag stood straight out from flagpole, and soaring gulls hung near-motionless in the sky.  Both provided evidence of the wind’s power.  The warmth of the day and the winds cooling effect were in perfect balance to produce a comfortable environment for activating, even though the breeze provided a bit of audio spectrum QRN.

The Activation

Caught from behind, while focused on incoming code…

I tossed a throw-line over a branch on one of the large trees near the shelter, and quickly hoisted up my Tufteln 35 ft end-fed random wire (EFRW) antenna.  With the antenna set up, I connected the rest of the station.  Moments later, my log was ready, and I was on the air.

I was able to spend an hour on the air, and with the EFRW and the KX2’s amazing internal tuner, I was able to rapidly transition between HF bands.  Operating CW mode at 5 watts, I was successful in making contacts on the 40, 30, 20, 17, 15, and 10m Amateur bands.  In total, I logged 30 contacts, including 3 DX stations from Europe, a thoroughly satisfying activation experience.

This map shows the contacts made from Lake Milton.  It was gratifying to get some DX during the last activation of our trip.

Gear

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Conclusion

Becky takes amazing pictures.  Here, another view of Lake Milton.

Packing up the station went quickly, and we were back in the truck and ready for the final leg of our trip.  In about 2 hours of driving, we were pulling into our own driveway for the first time in a month and a half.  It is difficult to fully describe the feeling.  It was really nice to be back home.  The prospects of sleeping in my own bed and relaxing in my own chair were really welcome.

But, at the same time, this adventure was over, and we would soon be back to our old routines.  After 6 weeks together, Becky, Molly and I would again be headed in the different directions occasioned by our day-to-day activities.  So, there was gladness of a return to the familiar, combined with the bittersweet feeling of the end of our travel adventure.

As I think about our trip from the distance of almost 6 months, and a long, cold winter, I realize that I am ready to start thinking seriously about our next driving (and radio) adventure!

Home.  After 6 weeks and 7300 miles, it was nice to get back…

Best 73 de Brian, Becky es Molly

Field Reports, Guest Posts, News, Portable, QRP, Videos

Cherry Blossoms, History, and POTA in Ritsurin Garden

6 Comments

by Mark (JJ5GVY/KB2PIZ)

My wife and I visit Japan every year for 3 to 4 months, usually in the spring. This year, we arrived in early March, and the weather was a bit cold. However, recently, we’ve seen the temperature turn quite warm and mild, with the cherry blossoms just beginning to bloom! It’s a perfect day to play radio!

Since we live in Takamatsu on Shikoku Island, we have easy access to Ritsurin Park (JP-2051).

Wednesday, March 26, was a perfect day for my wife to stroll through the park while I played radio.

Here is the gazebo where I set up shop.

The History of Ritsurin Garden

It is believed that Ritsurin Garden was originally created in the late 16th century, from a garden belonging to the Sato Clan located in the southwest corner of the present garden.

What is now the Nanko Pond was created around 1625, when Takatoshi Ikoma ruled the Sanuki Province (present-day Kagawa).

In 1642, Yorishige Matsudaira began ruling the Takamatsu Domain and inherited the garden. He and the successive generations of his family kept developing the garden over the years, and the 60 scenic spots were named when the domain’s fifth lord, Yoritaka Matsudaira, was in power in 1745. Continue reading Cherry Blossoms, History, and POTA in Ritsurin Garden →