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

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

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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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Accessories, News

ABR Industries 20% Off Site-Wide Sale (May 21 – June 2)

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Just a quick note: ABR Industries—known for their high-quality, US-made coaxial cable assemblies—is running a 20% off site-wide sale now through Monday, June 2nd.

Here are links to some of my favorite ABR cable assemblies:

We’re proud to be an affiliate of ABR, so any purchase you make using our links also supports QRPer.com. Thanks as always for your support!

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

A relaxing activation at Fort Harrison State Park

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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.

Events, FDIM, News, QRP

Mike’s 2025 Four Days In May (FDIM) Photo Gallery

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It’s hard to believe that Four Days in May (FDIM) 2025 has already come and gone—and even harder to believe that attendance was even larger than last year!

What an amazing event.

As always, FDIM is my favorite part of the Dayton Hamvention weekend. If you’re a QRPer and haven’t made it to FDIM yet, I can’t recommend it enough—this gathering is pure QRP energy from start to finish.

I truly enjoyed meeting so many QRPer readers and supporters in person. Thank you for stopping by and sharing your stories—it was an absolute highlight for me!

Once again, I was so busy chatting and connecting that I barely had time to snap any photos. Thankfully, my friend Mike (VE3MKX) came to the rescue with another fantastic gallery.

Thank you, Mike!

Photo Gallery

Click to view the entire photo album–> Continue reading Mike’s 2025 Four Days In May (FDIM) Photo Gallery →

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

The POTA Babe Tries the CFT1

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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 →

Hamvention, News, QRP Radios

Hamvention 2025 Day 2: I Couldn’t Help Myself…

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Good morning, QRPers!

Day two of Hamvention 2025 was absolutely amazing—and the weather couldn’t have been more ideal. I wish I had time this morning to write a proper recap, but I’m grabbing a quick breakfast and heading back to the Greene County Fairgrounds for day three.

That said, I wanted to drop a quick note and share a photo of a little surprise from the Flea Market…

Even though I told myself I wouldn’t buy another radio at Hamvention, I spotted one I simply couldn’t pass up:

I already own a TR-35 (a rig I absolutely love), so I let that one go. But I didn’t have an MTR-4B in my collection… and that red chassis in the early morning sunlight? Irresistible. The asking price was $200—very fair, in my opinion—so I snagged it.

Later that day, I showed it off to my good friend Joshua (N5FY), and wouldn’t you know it—he gifted me one of his MTR-4B protective covers!

As soon as I got back to the hotel room that evening, I installed it.

She’s ready for the field.

 

I’ve actually wrote a review of an MTR-4B I borrowed from a reader. You can check out that review with links to field report here. I’m looking forward to taking this little red machine out to a summit soon!

More to come after Hamvention wraps up.

Thanks again to everyone who’s stopped by to say hello—it’s truly been the highlight of my weekend!

— Thomas (K4SWL)

FDIM, Hamvention, News, QRP

Day One at Hamvention 2025: Friends, Fun, and One Cancelled Reservation

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Good Morning, QRPers!

Day one of Hamvention 2025 (Friday, May 16) kicked off bright and early!

I started the day with a quick walk-through of the Hamvention Flea Market before the gates opened. I also shared an impromptu video with Patreon supporters—it was a peaceful moment before the weekend’s whirlwind began.

I spent most of Friday at the Ham Radio Workbench Podcast table, which served as a kind of home base. I had the pleasure of chatting with so many HRWB listeners, QRPer readers, and YouTube subscribers.

My dear friend Mike (VA3MW) shows off the new Flex Aurora.

Thank you for taking the time to introduce yourselves—it was a true joy to reconnect with many of you in person! Your kindness and encouragement fuel me through the wonderful chaos that is Hamvention.

First Stop: The Yaesu FTX-1 Field and Optima

As soon as the indoor exhibits opened, I made a beeline to the Yaesu booth to check out their new FTX-1 Field and FTX-1 Optima. They had multiple units on display, ready for hands-on testing.

In person, the rigs look fantastic—the displays are crisp, the fit and finish are excellent, and I really appreciate the modular design with snap-on battery and ATU options.

That said… my first reaction was: “This is bigger than I expected.” I wasn’t alone—I overheard several others expressing the same surprise.

I think that’s partly due to some early promotional material. One Yaesu rep video seemed to suggest the FTX-1 would be just a bit larger than the faceplate of an FTM-500D.

In reality, it has a much larger footprint. Even with just the battery attached, it has noticeable bulk—and with the optional ATU in place, it grows even more.

The Optima version, with its 100-watt amplifier and internal ATU, is larger still—definitely a full-size 100-watt rig. I’d say it’s bigger in every dimension than the FT-891.

I also recorded a quick video with my iPhone while checking out the FTX-1 at the Yaesu booth and shared it on YouTube yesterday, if you’d like a closer look.

Why I Cancelled My FTX-1 Reservation

After spending some time with the FTX-1, I walked over to DX Engineering and cancelled my reservation.

To be clear: I think Yaesu has done a great job with this rig. It’s incredibly feature-rich, well-built, and will no doubt be the perfect radio for a lot of operators. I’m willing to bet Yaesu will sell a ton of these—and rightfully so.

But for my specific needs—especially as someone who values small, minimalist radios for portable field use—the FTX-1 simply isn’t the right fit. Even the head unit of the FTX-1 Field is larger than I prefer. I could tell that, as much as I might enjoy the radio at home, I’d likely leave it behind more often than take it to the field.

So this was a personal decision, and canceling also frees up over $2,000 in funds for other gear that better aligns with my style of operating.

One thing I heard repeatedly throughout the day–a number of folks who had pre-ordered the FTX-1 Field through Ham Radio Outlet were frustrated. Several told me they were surprised—and disappointed—that HRO had a batch of FTX-1 Field units for sale at Hamvention, even though some customers placed reservations months ago.

These folks followed HRO’s instructions last year to reserve early and expected to be first to receive units in-hand.

Update: Two readers have noted that their FTX-1s reserved via HRO actually shipped on Friday, so perhaps all or some of the reserved orders actually shipped day of Hamvention.

Wrapping Up Day One

Mike (VA3MW) snapped this photo of us at the HRWB table.

Hamvention day one was absolutely amazing—but I’ll admit I was wiped out by the end of it (and I know I wasn’t alone!). I did make it to Club Night at Four Days In May (FDIM), but we headed back to the hotel early—just in time to avoid the intense storm that rolled through Dayton around 8:30–9:00 p.m.

I’m wrapping up this post over breakfast, then heading back to the Greene County Fairgrounds for day two. I can’t wait to see what’s ahead!

Once again, thank you to everyone who stopped by to say hello. Your encouragement and kindness truly mean the world to me.

— Thomas (K4SWL)

FDIM, Hamvention, News, QRP, Travel

Trip Report: Road to Hamvention 2025 and Four Days in May

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I’ve got a few quiet moments this morning as I sit in the dining room of our hotel in downtown Dayton, Ohio. It’s peaceful here—no one else is around, and no one has turned on the TV. Bliss…

Of course, that’ll change in a couple of hours when we pull into the parking lot at the Greene County Fairgrounds for Hamvention 2025!

So far, the trip and Four Days in May have been amazing.

I left Swannanoa bright and early Tuesday morning in the rain, but it cleared up as I crossed into Tennessee. The theme of the day was passing through thunder showers as I made my way north.

The plan was to activate Camp Creek State Park (US-5584) in West Virginia, grab lunch, then head to the QTH of Eric (WD8RIF).

I rolled into Camp Creek around 11:15 in light rain. Eric had confirmed there was at least one picnic shelter in the park, so I figured I’d activate from there to avoid scrambling if a downpour started.

I grabbed my end-fed half-wave and throw line from the back of the car—but then heard a very distant rumble of thunder. It was barely audible, but I decided to play it safe and set up under the metal shelter roof using my AX1 vertical instead. If I could wrap up the activation in 10–20 minutes, I could be packed up before any storms moved in.

It only took two minutes to set up the KX2 and AX1. I started scanning 20 meters for an open frequency, but could only hear one ragchew in progress—the band was otherwise dead.

I called QRL on 14,033.5 kHz, hoping for the best, when a loud clap of thunder hit.

Ugh.

I don’t mix radio and thunderstorms, so I packed up quickly, tucked in my tail, and hit the road. Camp Creek will have to wait for another day.

For lunch, I stopped at Tamarack in Beckley, WV. While the dining area might look like your typical folk art center café, the food is exceptional—the staff are in training for the famous Greenbrier Resort. I had a trout filet with green beans and mushrooms, kale, and sweet potato fries. It was incredible.

After a relaxed lunch, I hit the road again. A couple of hours later, I crossed the Ohio River and rolled into Ohio.

I arrived at Eric’s QTH around 4:30 and was warmly greeted by my canine buddy Theo—“The Great Warg” himself. You might remember him from some of Eric’s previous POTA adventures.

The Great Warg with WD8RIF circa May 2022.

Eric and I packed the car and headed into uptown Athens, Ohio for a quick bite.

On Wednesday morning, we hit the road early and activated Lake Alma State Park (US-1967), then headed to Great Seal State Park (US-1954) for a second activation.

Lake Alma State Park (US-1967)

While conditions were a bit unstable, we didn’t have to work too hard to complete both activations. (Full field reports and activation videos are coming soon.)

Great Seal State Park (US-1954)

Afterward, we drove another 90 minutes to Dayton and made a few stops at Wright-Patterson Air Force Base, including the clothing store—where I stocked up on my usual Rite in the Rain pads—and the Commissary, where Eric picked up his annual supply of Nutella!

We checked into our hotel and later grabbed dinner at Carillon Brewing Co., one of my favorite spots in Dayton.

Yesterday, we left the hotel around 7:00 AM to attend Four Days in May at the Holiday Inn Fairborn.

I wish I had more time to describe what an incredible event it was—truly a highlight of the year!

L to R: Vlado (N3CZ), Thomas (K4SWL), and Phil (W9IXX)

We wrapped up the day at a jam-packed Vendor Night. And I do mean jam-packed—it was shoulder-to-shoulder.

A huge thank you to the many readers and subscribers who introduced themselves. I truly appreciate it!

I’ll cap off this report now because it’s time to hit the road again. More to come!

News

On the Move! Heading to Four Days in May and Hamvention 2025

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Just a quick update: I’m heading out today for Four Days in May (FDIM) and Hamvention—both taking place this week—and will be on the road and fully immersed in the events for the next several days.

While I’m away, things may be a bit quiet here on QRPer.com.

My inbox is likely to pile up, and my posting may be limited while I soak in the energy, fun, and (let’s be honest) chaos of the world’s largest ham radio gathering and one of the best QRP conventions of the year!

Thanks for your understanding—and if you’re also attending Hamvention or FDIM, I hope to see you there!

72,

Thomas (K4SWL)

Field Reports, News, Pedestrian Mobile, Portable, POTA, QRP, Videos

Elecraft KH1 to the Rescue: Squeezing in a 20-Minute POTA Activation

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I feel incredibly fortunate to live in an area where a POTA park—the Blue Ridge Parkway—quite literally runs through town. As convenient as that is, I’ve still struggled to squeeze in activations over the past few months. We’ve had so much going on that even impromptu POTA time has felt out of reach.

Fortunately, I have a secret weapon for making the most of even the shortest activation window:

The KH1!

Left: My accessories pouch with contains a throw line, antenna adaptors, audio recorder, cables, spare key, and extras. Right: My Elecraft KH1 in a Pelican M40 case.

My Elecraft KH1 goes with me everywhere—it’s my proper EDC radio. And on Thursday, April 3, 2025, it came in very handy.

I dropped my daughter off at a physical therapist’s office, which just so happened to be right next to the Blue Ridge Parkway. Instead of waiting in the office for 45 minutes trying to catch up on email, I opted for some POTA radio therapy instead!

I left the parking lot and drove to a nearby gravel pull-off along the Parkway—just about four minutes from the PT office.

I hadn’t originally intended to film an activation, but I happened to have my camera, digital audio recorder, and a new magnetic clip-on camera mount with me.

I purchased this mount specifically to record pedestrian mobile activations. The first time I tried it, the results weren’t great: I mounted it at chest level, but my arms dominated the screen, making it tough to see both the radio and the logbook.

That Thursday, though, I had everything I needed—and I figured it was worth another try, this time clipping the camera mount higher and on my right shoulder.

With the clock ticking, I deployed the KH1 and hit the air!

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Radio and Antenna System

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On The Air

If you’ve done any POTA or SOTA activations in the past six weeks, you’ve probably noticed conditions have been rough—at times, downright miserable.

Luckily, I picked a day with reasonably good propagation. Continue reading Elecraft KH1 to the Rescue: Squeezing in a 20-Minute POTA Activation →

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