Tag Archives: Field Radio

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

WN5C: Notes from a homebrew POTA adventure

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Many thanks to Sam (WN5C) who shares the following guest post:

Notes from a homebrew POTA adventure

Sam (WN5C)

I recently wrote about the homebrew transceiver I built to operate on a month-long trip through the American Southwest. Upon arriving back in Oklahoma here’s the final outcome: 27 days, 40 parks, and 669 QSOs. I honestly can’t believe that the rig went the distance, or that I made so many contacts on 2 watts or less!

The priority of this trip wasn’t radio, though. I’m an archaeologist and I’m starting a new research project that marries my historical interests with my love of two-way communication. In short, I’m studying the effects of how communication technology aided the American colonization and transformation of the western United States around the turn of the twentieth century. This means I walked and mapped single-wire telephone lines strung up in pine trees in northern New Mexico (used to connect fire lookouts with Forest Service ranger stations), a fascinating story of dramatic changes in land management. I also visited heliograph (sun-mirror signaling) stations established in southeastern Arizona by the U.S. Army Signal Corps in 1886 to assist in apprehending Geronimo.

Working Fort Bowie NHS (US-0815) in Arizona. The peak in the distance, Helen’s Dome, had a heliograph station on top. From the fort telegraph lines would have connected remote operations to the rest of the Army’s 1880s communication network. Next time I’m climbing up on top!

I look forward to relocating and studying the artifacts from more of these heliograph sites (mostly on remote peaks) to reconstruct this communication network and understand the lives of both the soldiers and the Apache, and how this novel surveillance system altered the battlefield. Based on the artifacts I’ve seen so far there are many cans of Army-issued proto-Spam and beer bottles surrounding the signaling station where American Morse Code would have been sent and received via flashes of sunlight. The original Field Day?

But back to radio. I covered a lot of ground and activated parks in Oklahoma, Texas, New Mexico, Arizona, Utah, Colorado, and Kansas.

The POTA sites that I activated (click image to enlarge).

At some locations I was camping so I was able to do multiple long activations and work the lower bands well into the evening. These were some of my favorite moments of the trip, being the only spot on the POTA app and leisurely working with no time or weather-based worries. It also gave me a chance to hear callsigns I was unfamiliar with, essentially exploring a new area of the country.

Working closer states after hours on 30 and 40 meters at Colorado NM (US-0918).

For other times, due to time constraints or weather (thunderstorms or that it was unbearably hot), I got my 10 contacts and moved on. Sometimes I packed the equipment for a long hike, often carried it from the car to a picnic table, and a few times deployed my antenna and operated from my vehicle.

Not every activation was a grand adventure. Sometimes, like here at Rocky Mountain Arsenal NWR (US-0226) in Colorado, I worked from the passenger seat in the car.

Every activation was memorable in its own way. I worked folks from 44 states, five Canadian provinces, and an unforgettable contact from Italy.

A map of the contacts I made (not including those in northern British Columbia, Alaska, and Italy).

The radio held up surprisingly well. Aside from it looking like a Dalí painting as the 3D printed box continued to deform in the heat, and some hot glue remelting, the electronic components worked as they should. I look forward to printing a stronger case and making some upgrades going into the fall. I do now have a real respect for the engineering that goes into designing field radios, especially those that are thrown into a pack!

Setting up a portable shack on Vail Pass in the White River NF in Colorado (US-4410). This was near the end of the trip, the plastic case was looking pretty bad.

After I began feeling less anxious about the homebrew radio (it kept turning on!) I could start focusing on the trip itself: an amazing POTA adventure with an often-uncooperative sun. Here’s a few themes I noted. Continue reading WN5C: Notes from a homebrew POTA adventure →

Articles, Field Reports, Guest Posts, Kits, Morse Code, News, Portable, POTA, QRP, QRP Radios, QRPers, Travel

Sam’s Thunderbird Mk 1 Takes Flight: A Homebrew Radio Field Report from the American Southwest

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Many thanks to Sam (WN5C) for sharing the following guest post:

Homebrew in the Field

by Sam (WN5C)

What a week it’s been!

I have the opportunity to spend a month traveling through and camping in the American Southwest (specifically, New Mexico, Arizona, and Colorado) doing archaeological work. And of course, that means the prospect to operate portable at weird times and in lots of places.

I’ve been planning for this trip for a couple of months, about the same length of time that I’ve been trying to achieve my amateur radio dream: to build a complete transceiver. So why not try to do both things at once?

This is just a quick note of my experiences in the first quarter of my trip of taking a homebrew rig into the field.

First off, I have absolutely no background in RF engineering, or electronics at all. But the literature is good and Elmers are priceless (thanks Kenn KA5KXW!). I started small, with kit projects, and then very basic transmitters.

I’ve always appreciated how much satisfaction my father gets by building things by hand, and finally I have a similar hobby. I called the radio I designed the Thunderbird Mk 1 based off the fact that I cut my CW and POTA teeth at Lake Thunderbird State Park in Oklahoma and will probably continue to work there the most. It’s a 6-band (40, 30, 20, 17, 15, 10) CW QRP transceiver with SSB receive.

The receiver is direct conversion and is an amalgamation of VU2ESE’s DC40, KK7B’s Classic 40, and W7EL’s Optimized QRP Transceiver. The VFO is an Arduino/si5351 combo based on the schematics and code written by VK3HN (who has helped me from afar, thanks Paul!). It’s crude, but I use a 6-position rotary switch to manually switch between the band-pass filters.

The transmitter is based on W7ZOI’s Updated Universal QRP Transmitter, married with VK3HN’s Arduino code that acts as the oscillator, keyer, and side tone generator. I get about 3 watts output for 40, 30, 20, a little less for 17 and 15, and about a watt on 10 meters. Like the receiver, I manually switch the low-pass filters.

Here’s a picture of the digital parts (ignore the second Arduino Nano, I thought I would need it but did not), the power board, and the filters. It’s on the bottom:

On top is the main board with the receiver, the transmitter, and T/R switching. Also, you’ll notice the green PCB. I *really* wanted to build NM0S’s Hi-Per-Mite from scratch but I couldn’t get the circuit to run right before my trip so I opted to install one that I built from a kit. It’s a fantastic CW audio filter that I can switch in and out (everyone should have at least one!).

I can switch in a little speaker and added a straight key jack. I printed the box on a 3D printer at the local library. It works great for the shack. In the sun, it’s starting to warp in the heat, so I’ll have to address this, but things still work!

Getting out the door on time with a finished radio was tough! I had finished right before I left on my trip (end of May 2024) and had no time to field test. The best I got was taking the rig to the table in the back yard and firing it up during the WPX contest.

I made amazing DX contacts on all the contest bands I had and called it good. But working superstations isn’t real life, and over the next week I’ve had to MacGyver the radio (rigging a car jump pack, an inverter, and a soldering station together at a picnic table to replace a bad transistor, for example). I think I’ve finally shaken out (literally) all of the loose solder joints and bad grounding. Continue reading Sam’s Thunderbird Mk 1 Takes Flight: A Homebrew Radio Field Report from the American Southwest →

Comparisons, News, Pedestrian Mobile, Portable, QRP, QRP Radios, Videos

The Elecraft KH1 or KX2? Which one should you buy?

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Even before I started taking my Elecraft KH1 to the field and generating reports and activation videos, I started receiving questions from readers and subscribers about how the KH1 might compare with other field-portable radios.

At least 70% of all of these questions asked specifically about the venerable Elecraft KX2.

Making a purchase decision

I’m not surprised so many are trying to make a purchase decision between the KH1 and KX2.

For one thing, the KH1 and KX2 represent some of the smallest, most compact and lightweight shack-in-a-box HF field radios on the market. We’ve a lot of QRP field radios to chose from these days, but few have options for both internal ATUs, internal batteries, and attachable paddles. Very few are as light and compact as either of these two radios.

Another reason for the comparison is that many are in the long queue to purchase a new Elecraft KX2. At time of posting this article, if you place an order for the KX2, you are going to wait a few months for delivery.  The KH1 also has a lead time, but it’s likely shorter than that of the KX2 (check out the Elecraft Shipping Status page for more info).

Comparing models

While the KH1 and KX2 have a lot in common, they’re also quite different in many respects.

We radio ops like to compare features and specifications and Elecraft knew the KX2 and KH1 would be compared frequently, so they created a handy chart:

Click here to download Elecraft’s KX2 v KH1 comparison chart (PDF).

At the end of the day, though, I would argue that one’s enjoyment of a radio has more to do with how well it fits the operating style of the owner.

The KX2 is one of the best portable QRP field radios ever made, in my humble opinion. It’s a little high-performance machine that can handle any mode you care to use between 80-10 meters.

The KH1, on the other hand (pun intended), is designed to be an exceptional handheld radio for pedestrian mobile use and as a super lightweight, low-impact, field portable station. It’s essentially CW-only and operates on 5 bands (40-15 meters).

If you can be honest with yourself about how you plan to use the radio, it’ll help you make this purchase decision.

For example, if you never see yourself operating pedestrian mobile–you’re more of a sit down at a table sort of op–there’s a good argument to go for the KX2. If, however, you’re an avid SOTA/POTA portable activator who is primarily a CW op and you like the idea of a super quick deployment and handheld operating from anytime, anywhere, you should consider the KH1.

Video

To dig into this comparison a little deeper, I decided to make a video where I discuss the differences between the two radios and also speak to different styles of operating and which radio might suit that style best:

Click here to view on YouTube. 

I would be curious which radio you prefer and why. Please consider commenting!

Thank you!

I hope you found this post and video useful.

As always, I’d also like to send a special thanks to those of you who have been supporting the site and channel through Patreon and the Coffee Fund. While certainly not a requirement as my content will always be free, I really appreciate the support.

Patreon supporters have access to 100% ad-free, and downloadable videos for off-line viewing via Vimeo. The Vimeo account also serves as a third backup for my video files. This is how your support truly helps this site and channel!

Cheers & 72,

Thomas (K4SWL)

Antenna Tuners, Antennas, Homebrew, How To, News, Portable, QRP

BD4LB’s Simple Homemade L-Match for Field Operating

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Many thanks to HUAQIANG Gu (BD4LB) who shares the following information about his homemade L-Match. Note that BD4LB doesn’t speak English, and I don’t speak Chinese, so the following was machine-translated via Google Translate:

Homemade L-Match for Field Operating

by HUAQIANG Gu (BD4LB)

L-MATCH has a simple structure and is easy to make.
It is mainly composed of a coil and an adjustable capacitor.

  1. The coil is made of copper wire with a diameter of 1.8mm, and the outer diameter of the coil is 50mm.
  2. The capacitance of the thin film adjustable capacitor is 0pF–200pF.
  3. When using, a balanced ground wire needs to be installed.
    (Different bands, multiple quarter-wave length wires, and together. I use a row of wires. For example: two balanced ground wires 10 meters and 5 meters long, respectively 40 meters band and 20 meters band balanced ground wire.)

After many outdoor communications, I adjusted the end-fed antenna. The length of the radiator was 10 meters, which was appropriate.

One end of it is hung from the top of a 6-meter-long fiberglass fishing rod. On the other end, connect the red binding post of L-match.

Balance the ground wire and connect it to the black binding post. Spread it out on the ground.

The L-match is placed on the ground and connected to the HS1B or KVE60C antenna analyzer using a one meter long 50-3 coaxial cable. (This reduces the length and weight of the coaxial cable.)
When using an inverted V antenna, the length of the coaxial cable needs to be at least 8 meters.

My outdoor communication is mainly on the top of a hill in the park, or on the beach by the sea.

On the beach, there is plenty of space. In addition to setting up end-fed antennas, you can also set up inverted V antennas.

On the top of the mountain in the park, the space is limited, and it is difficult to deploy the 20-meter-long antenna oscillator. Only 10-meter end-fed antennas can be used.

After fixing the fishing rod, installing the antenna radiator and balanced ground wire, first connect the antenna analyzer KVE60C.
Use copper alligator clips to clip on the coil and adjust the adjustable capacitance to minimize the standing wave ratio of 7.023 MHz.
(Change different coil taps, adjust the adjustable capacitor, and try several times.)

I carry a compass to adjust the transmitting direction of the end-fed antenna. I won’t get lost.

The actual communication effect is quite good.

In the 40-meter band, it is suitable for short-distance communication within 800 kilometers.

In the 20-meter band, it is suitable for communication within 1000-2000 kilometers.

Accessories, Articles, Field Radio Kits, Field Reports, Grab And Go, Morse Code, News, Portable, POTA, QRP

Testing my new Headrest QRP POTA Field Kit!

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I love field radio kits.

If you’ve read my “Anatomy of a Field Kit” series, you’ve likely gathered that field kits are a bit of an obsession. [Yeah, understatement alert!]

My field kits roughly fall into two main categories: modular and fully self-contained. My modular kits are ones where components like the battery, antenna, throw line, key, and radio are in separate pouches and can easily be combined to make a complete station before I leave for an activation.

My fully self-contained kits are ones that quite literally have everything needed to perform a park or summit activation in one pouch or box. A good example that I’ve documented here is my MTR-3B field kit.

For more on this, again, check out my “Anatomy of a Field Kit” series.

Vehicle kit

If you’re a devoted park and/or summit activator, I think it’s important to keep a dedicated kit kit in your car at all times. Why?

  • It’s ready to grab for impromptu activations
  • It’s handy in case of road-side emergencies in remote areas
  • It’s always  accessible to demonstrate amateur radio to those who are curious
  • It’s always always there for those times when you hadn’t planned to play radio, but the opportunity presents itself

I always have a full radio kit in my Subaru and over the years, I’ve changed and adapted it. For the most part, though, it’s been located in the trunk/boot and lives with anything and everything else I keep back there. Sometimes, it’s in the way when we need to fill that trunk space with family items for a trip or when we’re hauling things around town. Other times, it’s floating/sliding around freely in the back.

On long family trips, I’ve been known to store radios under the floor, but it’s a true hassle to remove them because I have to remove anything in the trunk before lifting the floor.

Contraband I hid in the car during our two month Canada trip last year.

I’ve always wanted a way to store my kit in the car in a dedicated space. In the past, I’ve tried to make a kit that could fit under the driver’s seat–thinking that might be ideal–but there’s very little clearance under it and it’s difficult to remove.

Enter the BROG Headrest Pouch Kit

Before I placed my initial order for the Blue Ridge Overland Gear (BROG) Gadget Bag, I checked out other items on their website. One that immediately caught my attention was their Headrest Kit.

It consists of a Velcro panel that fits around a vehicle headrest and a pouch (or pouches) attach to it.

BROG caters to Overlanders and vehicle storage/organization is huge in that community. The headrest kit makes a lot of sense: it’s using space that’s accessible, doesn’t interfere with any passengers, is off the floor, and is otherwise underutilized!

The big questions, of course:

  1. would the pouch offer enough space to store an entire radio kit,
  2. and would the kit weight too much for the Velcro back to hold it in place?

I asked for the Headrest Pouch Kit ($47.99) to be sent with my Gadget Bag order.

BTW: Big thanks to BROG for giving me flexibility with this order. Since I had no experience with their gear, I asked that they send me a list of items and allow me to evaluate them, then pay (full price) for what I decided to keep. 

Would it work?

I knew I’d need to store a very small transceiver in this dedicated pack. A few could potentially fit the bill–namely the:

  • Mountain Topper MTR-3B
  • Venus SW-3B
  • QCX-Mini
  • TEN-TEC R4020

I eliminated the QCX-Mini from this list because it’s mono band (mine is set for 20M) plus, I really love the field kit I already designed for it. Same for the MTR-3B–the kit I built for it is now time-tested and I love it as-is. The R4020, while quite compact, is the largest in this group of wee rigs. Continue reading Testing my new Headrest QRP POTA Field Kit! →

Guest Posts, How To, Radio Field Craft

Radio Field Craft: Rand explores the handy Prusik Knot

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Many thanks to Rand (W7UDT) who shares the following guest post:

The Prusik Knot… strain relief for Wire Antennas and Coax.

By W7UDT, Randall ‘Rand’ Tom

The Prusik knot is a simple, yet effective means to provide needed strain relief to wire antennas and coax, while deployed. It’s comprised of a simple loop or length of suitable cordage (of smaller diameter than the shank, Coax or Wire, it secures).

The link below, is from our friends at Animated Knots…. It’s a brief video tutorial on how best to tie the Prusik knot. Having the Prusik in your ‘bag of tricks,’ will help make your next field deployment be a successful one.

https://www.animatedknots.com/Prusik-knot

As seen in the instructional video, the knot is comprised of a simple loop of cordage, sufficient in length for the task, which is fine, but, I would recommend NOT making a loop. Rather, keeping tag ends for easier anchoring. These tag ends should be at least 12” in length. This is called an open-ended Prusik. Either way, both have utility.

To do this, fold a 24” of cordage in half, to make a ‘bite.’ Lay the bite over the shank of the coax or wire, and feed the tag ends inside the bite loop. This forms a larks-head knot. Wrap two additional turns around and through, then dress and test the knot to form the Prusik. Simple. Anchor (tie) the tag ends at a point where strain relief is best positioned. Then adjust (slide) it to load.

After deployment, I would also recommend leaving the Prusik attached. It comes in handy, when coiling your feed lines or elements later for proper storage.

The Prusik allows it to slide along the wire or coax while free of tension, yet it holds fast under load. Much like a monkey’s fist hanging onto a vine. The tag ends, can then be affixed to suitable anchor where needed. The key here, is using a smaller diameter cordage, than the wire or coax itself.

The Prusik, along with similar ‘Friction Hitches’, can be used in any number of applications in Ham Radio. e.g. Anchoring coax, joining linked antenna elements, power cords, and adjustable guying. The list is long, wherever strain relief is needed.

I would encourage you to tie it, try it, test it, and judge for yourselves. As well, I would encourage you to check out other useful climbing friction hitches… YouTube is a great place to start. I hope you find this useful afield, and to hear you ‘On the Air!’

73! de W7UDT (dit dit)

W7UDT, ‘Rand’, lives and operates near Boise Idaho, with his lovely wife Stacy. Portable QRP operations, along with his Jeep and Harley are his ‘vices.’ Your comments and questions are welcomed. My email is [email protected].

Hams, Morse Code, News, Portable, QRP

Treetop Antennas: Featured with my friend Wlodek (US7IGN) on BBC Radio 4 Short Cuts

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I’m very honored to be featured with my good friend Wlodek (US7IGN) in a short radio documentary on BBC Radio 4 today.

Wlodek is long-time reader and subscriber here on QRPer.com and the SWLing Post. Wlodek lives in Kiev, Ukraine and we keep in touch these days over email. Like me, he is passionate about field radio work and before the Russian invasion, you’d often find him in nearby forests experimenting with some pretty impressive field antennas.

Sadly, when Russia invaded Ukraine earlier this year, it very quickly brought an end to all of that for Wlod. Not only were amateur radio operators not allowed to transmit under the state of emergency, but it’s no longer safe to venture into nearby forests.

Radio producer, Cicely Fell, learned about our love of all things field radio and put together an audio piece that airs today on BBC Radio 4:

BBC Radio 4 Short Cuts

From the forests of North Carolina, USA to the city of Kyiv, Ukraine – two ham radio enthusiasts seek each other out and a voice from the past prompts a dialogue on listening between a rabbi and a radio producer.

Click here to listen via the BBC Radio 4 website (note that the audio can be streamed shortly after the program airs today).

Many thanks to Cicely and her talented team at Falling Tree Productions for spending a little time with us in the forest and on the air! Truly an honor.