All posts by Thomas Witherspoon

Alex builds a simple sideswiper

Many thanks to Alex (W3AVP) who shares this photos of his homemade cootie/sideswiper originally posted on the POTA Faxcebook page. Alex notes:

I didn’t want to lug my Begali key to the parks so I made my own using the plans from KA8VIT. Worked great! I had a little QRP key but my fat fingers would make so many mistakes. The DIY aspect of this hobby is extremely entertaining!

And I bet your “cootie” serves you well in the field! I love the simple design and the fact it even has an adjustable action. At the end of the day, keys are merely switches so are perfect for homebrewing!

If you have a sideswiper/cootie or any other key you’ve built and would like to share it here on QRPer, contact me (K4SWL at

Thanks for sharing, Alex!

642 Miles Per Watt with the new Icom IC-705 QRP transceiver

Thursday, I set out to test how long the Icom IC-705 could operate during a Parks On The Air (POTA) activation with one fully-charged Icom BP-272 Li-ion battery pack. This, following my listening endurance test.

I knew conditions were pretty terrible Thursday in terms of propagation, but that didn’t really matter. I intended to call “CQ POTA” in CW until the ‘705 finally shut down due to low voltage. In my head, I imagined this wouldn’t take much longer than 1.5 to 2 hours and during that time, despite propagation, surely I’d work 10 stations to validate the activation, right–?

Sandy Mush Game Lands (K-6949)

I picked Sandy Mush Game Lands as my test site. Since I’d been there before, I knew there were ample trees to hang the Vibroplex EFT-MTR end-fed antenna, and I knew I’d likely be the only one in the parking area as this site is secluded and this was not a designated hunting day.

The Vibroplex/End-Fedz EFT-MTR antenna

Setup at the site was pretty straight-forward. I quickly deployed the EFT-MTR antenna–using my arborist throw line–in a “V” shape hanging over a high tree branch.

I picked the EFT-MTR because it’s resonant on my three favorite POTA bands: 40, 30, and 20 meters. Note that the IC-705 does not have an internal ATU.

Although I have an mAT-705 external ATU on loan to test, I didn’t take it to this first activation–I wanted to keep the set up simple for testing battery endurance.

On the Air

I started calling CQ at 16:30 UTC on the 40 meter band and set the IC-705 to beacon mode call “CQ POTA K4SWL.” No replies for 10 minutes. At that point, I discovered the POTA spots website was down for a scheduled upgrade (I have impeccable timing!), so I posted my spot on the POTA Facebook page.

Then my buddy Mike (K8RAT) sent a text message stating that the Reverse Beacon Network (RBN) had spotted me, but with a very low signal report. Hmmm….why would that be?

Turns out, I still had the IC-705 power level set to “0” watts (this story might sound familiar). Doh!

Note to IC-705 owners: zero watts is not zero watts!

I turned up the power to 5 watts (the max the IC-705 will achieve on a 7.4V battery pack) and was greeted by an instant CW pile-up.

What a blast! I started on 40 meters in CW, but eventually worked both 40 and 20 meters in SSB and CW. I then lowered the antenna, removed the SMA cap on the EFT-MTR coil, and worked 30 meters CW for the remainder of my time.

I logged my first contact at 16:28, my last at 18:18 UTC. So 1 hour 50 minutes of near constant operating.

Remaining battery capacity after 1:50 of operating.

The IC-705 battery pack was still going strong and had about 40% capacity left, but I simply ran out of time as I needed to run an errand in town, so had to shut down the radio and pack up.

I must admit: the IC-705 is doing a much better job managing battery usage than I would have expected. I’m guessing I could have operated for 3 hours or so at 5 watts without needing to recharge the BP-272 1880 mAh Li-ion battery pack.

I do believe I’ll invest in the larger BP-307 battery pack which has a capacity of 3100 mAh. It’s a pricey battery, though, at $130 US.

How does the IC-705’s battery endurance compare with the Elecraft KX2? I’m not sure yet, but I’m guessing the KX2 will have even better longevity as its current drain is less than half that of the IC-705. The KX2 will operate at 10 watts output for about 1 hour 15 minutes with the internal battery pack, before decreasing to 5 watts output. I’ve never tried a battery endurance test with the KX2 at only 5 watts.

Of course, with an external 12 volt battery, the IC-705 will pump out a full 10 watts of power as well.

Five watts and a wire–wow!

The biggest surprise of the day?

I worked stations from Oregon, and Saskatchewan to the Azores…in single sideband!

Here’s a map of my contacts–red signal paths are SSB, CW in green (click to enlarge):

This was one activation where 5 watts SSB actually snagged more DX than CW. Great fun!

While I’d like to think it was a little IC-705 “mojo” on its first field outing, in truth it had everything to do with the EFT-MTR antenna and what must have been a moment of propagation stability.

This was also my maiden voyage with the CW Morse Single Lever paddle. CW Morse sent this paddle, along with their double lever paddle and a selection of straight keys, for me to evaluate. If you’ve been considering an affordable, portable single-lever paddle, this is a brilliant one. I really enjoyed using it and the action is very easy to adjust.

I’m already regretting the decision to send it to my buddy Eric (WD8RIF) for a proper evaluation. (Just kidding, Eric! (Maybe.)) He only uses a single lever paddle for his numerous field radio adventures.

Eric will give this single-lever paddle a proper workout and give us a full report.

I must admit, I had a lot of fun with the IC-705/EFT-MTR antenna combo.

Of course, I’ll be taking the IC-705 to the field a lot in the coming weeks.

IC-705 Questions?

Feel free to comment and ask any questions you may have about the IC-705. I’ll do my best to answer them.

The new Portable Operations Challenge this weekend!

(Source: Southgate ARC)

Portable Operations Challenge

The final rules for the FMH Portable Operations Challenge are now posted on the POC webpage at N1MM+ users, need to select FMHPOC as the contest and VKContest Logger users just POC.

The organisers wish all other contests taking place this weekend success and lots of fun – the bands will be busy again and we’re hoping propagation plays along.

We hope many amateurs give this new-style contest a go whether from a home QTH station or out portable.


Proud ham family…

Apologies in advance, but I need to brag a bit…

This weekend, both of my middle school-aged daughters passed their amateur radio exams with colors flying. Volunteers with the WCARS VEC were kind enough to meet us at a local park to conduct the test in a covered picnic area.

At the test site I was more nervous than my girls were, but I really had nothing to fear. Both were hitting a 95% pass rate on practice exams in advance.

Even though the girls have obviously learned a bit about radio through osmosis in this household, they did all of the exam prep on their own. Funny story: I remember allowing them both to send CW to my buddies K8RAT and WD8RIF on my lap when they were maybe 2 years old? Of course, they had no idea what they were sending, but they loved playing with the “clicky thing” (my paddles). I think WD8RIF actually copied their code to paper. 🙂 

I purchased both of them an FT-60R handheld radio from Universal Radio. I think these HTs should serve them well for many years to come!

I know one of my daughters is already chomping at the bit to pass her General now.

Anyway, thanks for letting me brag a bit here. I’m certainly a proud papa!

POTA Portable, Picnic, Paddles, and Unpredictable Propagation

Practicing left hand lunching, right hand keying/logging!

It seems like lately I’ve had to work hard to log 10-15 contacts during my Parks On The Air (POTA) activations.  Propagation has been so flaky, I use every trick in the book to snag at least my ten contacts for a valid activation: change antenna configuration, run up to 40-50 watts output, employ both CW and SSB, have friends spot me on the network, and try every band possible (typically from 80-17).

Note that the majority of my activations are proper QRP and rarely do I spend longer than 60 to 90 minutes actually on the air. Indeed, many of my activations are only 60 minutes long including set-up and take-down. That may seem short to most POTA folks, but that’s what works in my schedule and family life: quick hits. It’s one of the reasons I’m not more active in Summits On The Air (SOTA)–I need more time for those sites as they’re not as accessible as our numerous POTA entities.

Still, our local star has been misbehaving, and I had not planned to do an activation on Sunday (September 28) because I saw the propagation forecast and it was rather discouraging (A index 26, SW 505, Bz -2).

From home that morning, I chased a few parks but found it challenging to hear most of them. QSB was incredibly deep–strong stations gone in an instant.

Still, my wife suggested we take a picnic to one of our favorite local spots and how could I possibly visit a park without activating it? Right–?

Zebulon B. Vance Birthplace (K-6856)

What we, as a family, love about this site is the large covered picnic area and historic log cabins. Also, the site receives very few visitors on Sundays when the main museum is closed.

Each time we visit the Vance site, we bring my MSR liquid fuel stove and make lunch/dinner.

I set up the stove, got lunch started and my wife took over food prep.

Knowing propagation was unstable, I opted for more than QRP power this time–at least, at first–so I chose the Mission RGO One transceiver (capable of 55 W output) and CHA Emcomm III Portable antenna for this activation.

I deployed the Emcomm III in a sloping configuration with the end of the 73′ radiator high in a nearby (dead) tree and the counterpoise on the ground. I also suspended the winder/balun from the corner of one of the shelter’s rafter’s with paracord.

Since it’s difficult to see a wire antenna in photos, I’ve labeled the components in the following image (click to enlarge):

I didn’t know if this configuration would prove useful, but I knew it would be better than attempting this activation with my Wolf River Coils TIA vertical antenna.

I hopped on the air starting on 80M CW (at the request of my buddy WD8RIF), worked him and three stations in rapid succession. After a few minutes of silence, I moved up to the 40 meter band and worked 16 stations. I then moved to 30 meters and worked 11 stations.

I was working more stations than I would have ever guessed beforehand.

Since I only had about 10 minutes to spare after working 30 meters, I decided to plug in the microphone and work some park-to-park contacts. While I always intend to hunt for other parks while I’m in the field, more times than not, I don’t have the luxury of an Internet connection to check the POTA spots page like I did at Vance on Sunday.

I worked 5 parks: 3 in SSB and 2 in CW.

Speaking of CW, this was my first field activation using CW Morse Double Paddles.

CW Morse recently surprised me by sending a few of their products to evaluate in the field (guessing they saw my previous post asking about keys–?).

I must say, I really love the CW Morse double paddles. They’re fully (and easily) adjustable, the action is responsive and smooth, and with the base, they’re incredibly stable on a hard surface. I highly recommend them.

At a setting like we had at Vance, I love the heavy base plate, but if I planned to hike into a site, I believe I’d remove the base to save on weight.

Unpredictable Propagation?

Perhaps there was a brief window of stability between solar events and I was able to take advantage of that while I was on the air? I’m not sure.

I never expected to log 37 contacts in the space of a little over an hour (with some of that time being off the air to help with picnic prep). Not on that Sunday when the solar numbers were in the dumps.

I’d like to believe it was a combination of things:

  • A large wire field antenna with decent gain and the ability to work multiple bands
  • 40 watts of power (at first, I backed down to QRP on 30 meters)
  • Using CW for 34 of the 37 contacts
  • Perhaps unintentionally good timing

All I know is, I had a blast! It’s hard to beat a combination of good radio, good food, good scenery, and good weather!

I suppose this was also a lesson in simply hitting the field and ignoring the propagation.

Or as Rear Admiral David G. Farragut once famously said, “Damn the torpedoes, full speed ahead!”

An Introduction to the uSDX transceiver kit

Many thanks to Pete (WB9FLW) who shares the following article by Bob (KD8CGH) regarding the uSDX transceiver kit.

I reached out to Bob who has kindly given me permission to share his article on QRPer:

An Introduction to the uSDX

by Bob Benedict (KD8CGH)

There is a new open source, home brew multi band, multi mode QRP transceiver that grew out of the QRP Labs QCX. Through some serious wizardry  it retains an efficient class E RF amplifier for SSB and digital modes. It crams impressive SDR capabilities into an Arduino.

This has an interesting international development process conducted on with contributions by many, including the usual gang of suspects: Hans Summers G0UPL, Guido Ten Dolle PE1NN, Barbaros Asuroglu WB2CBA , Manuel Klaerig DL2MAN, Kees Talen K5BCQ, Allison Parent KB1GMX, Jean-Marie T’Jaeckx ON7EN, Ashhar Farhan VU2ESE,  and Miguel Angelo Bartie PY2OHH. I apologize to the many others whose names I didn’t list. A summary is in the WIKI

The basic work uSDX appears to have been accomplished by Guido Ten Dolle PE1NNZ. It uses pulse width modulation of the PA supply voltage to transmit  modes other than CW while retaining class E efficiency and uses a direct conversion SDR receiver.

The basic idea behind Class E nonlinear amplifiers is that transistors have little loss when they are switched fully on or off. The losses occur when devices are limiting power flow in linear amplifiers. The idea behind a Class E amplifier is to use transistors in a switching mode to generate a square wave to drive a resonant circuit to generate RF power.

This method is used in the popular QCX QRP CW transceiver kit line developed by Hans Summers and sold through QRP Labs  More than 10,000 of these great transceiver kits have been sold (I built one). There is a good discussion of the circuit and particularly of the class E amplifier in the excellent QCX documentation

The QCX was the base for the QCX-SSB which starts with a QCX and modified the circuit and software to add SSB capabilities. The wizardry that  Guido accomplished uses pulse width modulation of the PA supply voltage to control the amplifier in an Envelope Elimination and Restoration (EER) technique To generate SSB a DSP algorithm samples the  audio input and performs a Hilbert transformation to determine the phase and amplitude of the complex signal.  The phase changes are transformed into temporary frequency changes which are sent  to the  clock generator. This result in phase changes on the SSB carrier signal and delivers a SSB-signal with the opposite side-band components is attenuated.

On the receive side a direct conversion SDR receiver is used with the I and Q signal digitized and all further processing carrying out digitally. Attenuators are included to help not overload the ADC range.  Documentation is at .  In addition to a good description of the theory and hardware mod there is also a good description of the software command menu.

From there development took off in several directions. One is by Barbaros Asuroglu WB2CBA  and Antrak that uses through hole components (mostly) and replaceable band boards that  hold the low pass filter and band dependent class E amplifier components (an inductor and capacitor). Barb also includes boards designed to be a case top and bottom, battery pack and a PA.

Another development track by Manuel Klaerig DL2MAN uses SMT components in a stacked board layout and has a relay switched band pass board  and uSDX-Sandwich Files. A new revision has been released that uses serial resonance class E amp design and easier to obtain relays, uSDX-Sandwich Files with new Serial Resonance Class E Multiband Circuit .

Other development streams include one by Kees Talen K5BCQ uSDX Board Schematics and Jean-Marie T’Jaeckx ON7EN

I built the variant designed by Barbaros Asuroglu WB2CBA   and I’m pleased with it’s performance. I ordered 10 main boards and 40 LP filter band boards PCBs from PCBWAY, but now you can also purchase single boards sets from

I also designed and 3D printed a case for the transceiver and a small box to carry band boards. Info at and at and also in the files section printed case for Barb WB2CBA V1.02.

In an example of hams collaborating at its finest, Hans Summers  announced on 9/11/2020 that his new QCX mini product, a QCX in a smaller package,  will include a daughter board that can be used to give the QCX mini a uSDX like SSB capability. The QCX mini has the same circuit as the QCX but uses SMD components packaged it into a two board stack that is less than half the volume of the original QCX. The mod is unsupported by QRP-LABS but may be supported by the uSDX group. 

More information at and don’t forget the WIKI


Bob,  KD8CGH

Many thanks again, Bob, for sharing this excellent uSDX introduction. Thanks again for the tip, Pete!

Pete also notes that there is a very active uSDX experimenters discussion group on with over 100 members:

W9FKC’s suitcase portable

Many thanks to Pete (WB9FLW), who writes:

Found this link on the Soldersmoke Blog this morning.

Click to access W9FKC.pdf

Interesting to compare this 70 year old Rig with your KX2 or KX3!

We’ve come a long way since then.

Indeed we have, Pete! But, man oh man! What a gorgeous vintage portable–absolutely beautiful vintage example of form following function!

Click here to download the PDF.

Seven Park Activations in Six Days: A review of the adaptable Chameleon Emcomm III Portable antenna

Weather in North Carolina has been absolutely stunning over the past week, with the exception of two days where the remnants of Hurricane Sally dumped torrential rain. Two cold fronts provided us with gorgeous clear skies and dry conditions before and after Sally’s visit.

Of course, what better way to enjoy the outdoors than taking my radios to the field?

Last Wednesday, after several hours of knocking out home projects, my wife and I decided to enjoy the fall-like weather and get lost in Pisgah National Forest. My daughters were also keen for a little outdoor adventure, waterfalls, and hiking.

And our canine family member, Hazel? Always up for an outing!

“Let’s go, daddy!”

Of course, my wife was throwing me a bone as she knew I was chomping at the bit to try the new-to-me Chameleon Emcomm III antenna.

CHA Emcomm III antenna

Photo Source: Chameleon Antenna

I decided I’d pair the Emcomm III with the amazing Mission RGO One transceiver (a rig I’ll be reviewing in an upcoming issue of The Spectrum Monitor magazine).

Up to this point, I’d never used a Chameleon antenna in the field.

Chameleon Antenna kindly sent me both the CHA Emcomm III and CHA P-Loop a couple weeks ago for an honest field evaluation (and disclaimer: at no cost to me).

And being honest? The overall length of the Emcomm III wire antenna was intimidating.  I’m used to field-ready wire antennas that are perhaps 30-41 feet in total length. The Emcomm III has a 73 foot long radiator and 25′ counterpoise! Holy smokes!

In my head, I imagined the only places I’d be able to use the Emcomm III would be in an open park with large, widely-spaces trees.

Turns out, I was wrong.

Two things make deploying the Emcomm III a breeze–even in the middle of a forest:

1.) An arborist throw line: this piece of kit has revolutionized my  field antenna deployments. Not only does it give me the ability to suspend antennas much higher than I could before, but also to raise/lower antennas with ease compared with fishing line.

2.) The Emcomm III also has a floating dielectric ring on the radiator wire that allows you to create a suspension point. In fact, there are a number of ways you can deploy the Emcomm III which, I see now, makes it such a popular antenna among POTA operators.

To the field!

The first activation was actually a “two-fer”–meaning, two geographically-overlapping POTA park entities.

Wednesday, September 16: Pisgah National Forest (K-4510) & Pisgah Game Lands WRC (K-6937)

Propagation conditions on Wednesday were so crappy I found myself breaking with QRP to run 40 watts with the Mission RGO One into the Emcomm III. (The Emcomm III can actually handle up to 50 watts CW, 100 watts SSB.)

I first deployed the Emcomm III by pulling the radiator over a tree branch about 50′ high with the balun and winder near the ground. I then unrolled the counterpoise stretched out on the ground.

After only snagging about eight contacts in 50 minutes (a very meager amount for the typical park activation), I decided to re-configure the Emcomm III Portable so that it would act more like a NVIS antenna and perhaps grab a few regional hunters on 80 meters. There was no way I was leaving the forest without my 10 contacts to validate the activation!

I reeled in the radiator and re-attached my throw line to the floating loop and reconfigured the antenna to roughly match this “V” shape with a lower (roughly 25 ft) apex point:

NVIS “V” configuration (lifted from the CHA Emcomm III Portable product page)

I used the RGO One’s internal ATU to match the 80 meter band 1:1.

I started calling CQ on 80 meters CW and, evidently, the POTA site auto-spotted me via the Reverse Beacon Network (RBN) because within a minute, I found myself at the other side of a mini pile-up! I very rapidly worked 8 stations–most of them were in nearby Tennessee. These were callsigns I was not used to logging because typically they’d be under my skip zone–a little too local.

It was nice to get solid copy on 80 meters without the deep QSB on 40, 30 and 20 meters.

The thing that struck me about the Emcomm III at this first activation was how easy it was to reconfigure in the field despite the lengthy radiator. The wire is Copper Clad KEVLAR PTFE (Telflon-coated) and doesn’t easily tangle. It slides so easily through the trees–there’s no coil or bulky bits to get caught in the limbs.

When packing up, it wraps around its built-in winder very easily. Kudos to the designer.

Saturday, September 19: Pisgah National Forest (K-4510) & Pisgah Game Lands WRC (K-6937)

Last Saturday, I wanted to try the CHA Emcomm III in a different region of Pisgah National Forest and see how well it might pair with my Elecraft KX2.

We found an ideal spot to set up: a forest service road that had obviously been closed the entire season.

I deployed the Emcomm III Portable in the same “V” configuration as I did during the first activation, but this time raising the apex of the “V” up to 45 feet.

It’s important to note here that being a random wire antenna, the Emcomm III relies an an ATU to get good matches on each band. The Mission RGO One’s internal ATU did a brilliant job finding matches and, turns out, my KX2 did as well.

In fact, before I started calling CQ, I moved across the bands to see if I could get good matches with the KX2 ATU. From 80-20 meters, I think the highest SWR I had was 1.3:1. (The KX series ATU is truly a benchmark in my book!)

That day, even though the weather was gorgeous, propagation was terrible.  I read a few reports from experienced POTA and SOTA folks who couldn’t snag the needed 10 contacts for a valid activation earlier that day. There were contests and QSO parties on the bands so lots of signals–but more than once on the phone portion of the 40 meter band,  I could hear two stations calling CQ on the same frequency and trying to work the same stations totally unaware of each other. Not a good day to play radio in the field and was starting to wonder if I could even snag my needed ten contacts.

Turns out, I had nothing to fear.

Since I could, quite literally, pick any band the KX2 could transmit on, I was able to float across the HF spectrum, call CQ, and the RBN would make sure I was spotted properly to the POTA network.

Getting that first ten is a great feeling!

I pretty effortlessly snagged my ten, and then a number to boot.

When I seek a spot to set up in a national forest, I often look for forest service roads with locked gates. When I set up on an unused road, it typically means I’ll have a high branch to hang the antenna and also a little space to deploy it without touching other trees. Our spot on Saturday was ideal.

Again, hanging and deploying the Emcomm III was effortless. I did bring about 12 feet of paracord with me this time allowing me to tie off the end of the radiator if I chose the “V” shape.

Monday, September 21: Mitchell River Game Land (K-6926) & Stone Mountain State Park (K-2754)

Monday was another stunning weather day.

I decided I wanted to finally make a pilgrimage to an ATNO (All Time New One) POTA site I’d been eyeing for a few months: Mitchell River Game Land.

Because propagation was fickle and this site was a good 3 hour round trip from where I was staying with family, I planned to use the Mission RGO One and run 40-50 watts or so.

However, when I got to the site, I realized I’d left the RGO One’s power cable at home. Fortunately, I still had my Elecraft KX2, so 10 watts would have to do.

I found a large parking pull-off area surrounded by trees. There was a ton of room to deploy the Emcomm III.

I decided to extend the radiator in a sloping configuration and elevate the 25 foot counterpoise.

The configuration was Identical to the one above , but the balun/center winder and counterpoise were suspended about 4 feet off the ground.

I fired up the KX2  and started calling CQ on 80 meters. The RBN picked me up and the POTA site auto spotted me. In a couple of minutes, I snagged my first three stations, then I heard no other calls, so moved up to 40 meters where I worked a big pile-up of stations. It felt like a mini-DXpedition at times. I loved it!

I even hopped on the phone portion of the 40 meter band and worked a few stations, getting respectable signal reports despite unstable propagation.

This activation went so well and the weather was so ideal, I decided to fit in another park that was only a 30 minute drive and was new to me: Stone Mountain State Park.

The thirty minute drive was relaxing and reminded me how much I enjoy this portion of the NC foothills leading up to the Blue Ridge Parkway and escarpment.

By the time I reached the park it was 1:30 pm on a Monday and I essentially had the place to myself (even though in my head I was preparing for crowds).

I had my pick of picnic spots so I found the one with the highest branches. One shot with the arborist throw line and I snagged a branch that must have been 45-50 feet high.

I first deployed the Emcomm III by simply running the radiator over a tree branch and laying the counterpoise on the ground–much like I did in the first Emcomm III activation and deployment.

I started calling CQ and worked about 4 stations, then nothing. The bands simply died on me!

After 30 minutes, I reconfigured the Emcomm III into a similar “V” shape I used at Pisgah National Forest with the apex at about 40 ft and the center winder and counterpoise elevated about 3 feet.

After some persistence, I finished off my ten contacts and then packed up–I spent about 70 minutes on the air and needed to grab lunch!

I honestly believe I would have found this activation even more challenging if I didn’t have an antenna that could snag stations on the 80 meter band since it was in the best shape that afternoon.

Again, I was very impressed with how easy it was to reconfigure the Emcomm III.

Tuesday, September 22: Tuttle Educational State Forest (K-2754)

After staying two nights with my parents in the Piedmont of North Carolina, I made my way back home to the mountains Tuesday afternoon. Again, the weather lured me back out to make just one more activation! (Let’s face it: the weather is a bit of an excuse).

One of my favorite parks that’s only a 20 minute detour off my path is Tuttle Educational Forest. It’s never busy there and they have a large picnic area with ideal trees for hanging antennas.

After searching through my main field pack (a Red Oxx C-Ruck), I found a spare power cord that would work with the Mission RGO One transceiver.

I didn’t have a microphone, though. That’s okay: it would be a CW-only activation.

Although I had the park to myself, I didn’t want to take up a large portion of the picnic area by deploying the Emcomm III in a sloping configuration similar to my activation at Mitchell River. I decided, instead, to be space efficient and use the “V” configuration once again with the apex at about 35 feet and the counterpoise on the ground. By doing this, the antenna footprint could almost fit within my picnic table area (although my counterpoise did snake into the woods).

I can’t remember how long I was on the air, but I do remember it was a breeze logging contacts that afternoon. Very enjoyable. I do love the Mission RGO One–the receiver is amazingly quiet, sensitive, selective, and signals simply pop out of the ether. It also sports silky-smooth QSK. Again, although I’m 90-95% a QRPer, it’s nice to push the juice a bit when propagation isn’t kind. The RGO One will push 55 watts.

The Mission RGO One ATU also snags excellent SWR matches across the band with the Emcomm III.

Emcomm III initial impressions

This past week, I gained some serious respect for the Emcomm III.

What impresses me most is its versatility and robust quality.

Don’t get me wrong: it’s not a magic antenna or anything. It’s essentially a random wire antenna.

What makes it such a fabulous field antenna, though, is its configurability. That and its uncompromised military-grade construction.

I shouldn’t have been so concerned about the radiator length as it’s actually pretty easy to accommodate and helps make this an efficient antenna on the low bands. (Look for me activating parks on 160 meters this winter!)

I believe I can deploy the Emcomm III anytime I have a half-decent tree nearby. I believe I could also use my 31′ Jackite fiberglass pole to extend one end or even the middle of the antenna if I wanted to go NVIS, but I would have to be careful to accommodate strain relief since the Emcomm III Portable is made of heavier materials than my EFT Trail-friendly antenna, for example.

I’m not sure I’d ever reach for the Emcomm III for a SOTA activation when I’d need to take a close look at weight and size. But for POTA? It’s brilliant. And, of course, for emergency communications (as the model name implies). The Emcomm III would also be an excellent addition to a radio club’s antenna arsenal.

The Emcomm III, like all Chameleon products, is designed and made in the USA. Since they use military-grade components, you pay a premium.   The Emcomm III is one of their least expensive products at $139 US.  Is it worth the price? Absolutely. In fact, I’m thinking about buying a second one to keep in my camper.

Click here to check out the CHA Emcomm III Portable.

Moreover, the Emcomm III has earned its place in my main field radio kit.  Now let’s just hope Chameleon doesn’t ask for it back anytime soon!

Note that there are actually two models of Emcomm III antennas: the Portable version ($139) I reviewed here, and a Base version ($149) which is much larger designed for permanent installation.

Thank you, Chameleon Antenna, for sending me the Emcomm III Portable for a proper field evaluation. I’d also like to thank Chameleon Antenna for agreeing to be a sponsor of! 

A review of the Par EndFedz EFT-MTR triband antenna

Note: the following post originally appeared on our sister site, the SWLing Post.

The Par EndFedz EFT-MTR triband (40/30/20M) antenna

In July, I purchased a tiny QRP transceiver I’ve always wanted: the LnR Precision MTR-3B. It’s a genius, purpose-built little radio and a lot of fun to operate in the field.

It’s also rather bare-bones, only including a specific feature set built around ultra-portable CW operation.

While the MTR-3B has features like CW memory keying, a wide operating voltage (6-12 VDC), extremely low operating current (20 ma in receive), real-time 24 hour clock, and a full compliment of keying adjustments, it lacks other features like a volume control, SWR meter, speaker, and built-in antenna tuner.

Some of those may seem like big omissions but SOTA and POTA activators who like extremely lightweight/portable gear love the MTR-3B for being so purpose-built.

The MTR-3B (and its predecessors) operate on three bands: 40, 30, and 20 meters. These are, without a doubt, my favorite bands when operating portable since antenna lengths are reasonable.

Since the MTR-3B doesn’t have an internal ATU, you need to pack an external tuner or, better yet, a resonant antenna–ideally, one that can be used on all three bands.

Although many of my portable transceivers have built-in ATUs, I rarely use them because I primarily operate with resonant antennas. Resonant antennas are more efficient–giving you the maximum mileage per watt. In addition, they’re also more simple: connect them to the rig and hop on the air. No tuner or tuning required.

Since I keep self-contained field radio kits, my MTR-3B needed a dedicated resonant antenna.

The EFT Trail-Friendly antenna is incredibly compact and quite easy to deploy.

I’ve mentioned in previous posts that I’m a big fan of the Par EndFedz Trail-friendly EFT tri-band antenna (above) which is resonant on 40, 20, and 10 meters.  I’ve activated well over 130 parks with this little antenna.

After I took delivery of the MTR-3B, I borrowed the Trail-friendly EFT antenna from my KX2 field kit. It worked well on 40 and 20 meters, but it doesn’t cover the 30 meter band. Also, by borrowing the EFT from the KX2 kit, I broke one of my rules: never borrow from one field kit to feed another. This led to me leaving the EFT hanging in a tree at a remote park and returning a week later–a three hour round-trip(!!!)–to retrieve it. (FYI, in all fairness, I also blamed my trusty canine companion for this mishap!)

Enter the Par EndFedz EFT-MTR triband antenna

A few months ago, Vibroplex purchased the Par antenna line from LnR Precision.

I was very pleased with this decision as I’m guessing LnR Precision wanted to hand off antenna production so they could focus on the very popular Mountain Topper transceiver line.

Vibroplex is owned by my buddy, Scott Robbins (W4PA), who is not only a successful entrepreneur, but also an award-winning contester and DXer. I’ve known Scott for years and knew he’d not only be a great steward of the Par product line, but also push new innovations.

I emailed Scott asking if Vibroplex had a field-portable antenna that would be resonant on 40, 30, and 20 meters. Turns out, there’s a Par antenna designed specifically to pair with the MTR-3 series transceivers: the Par EndFedz EFT-MTR.

Scott pointed me to a description of the antenna on the Vibroplex website:

The new EndFedz ® EFT-MTR is a 40m/30m/20m tri-band QRP antenna rated up to 25 watts. The “MTR” name was selected as LNR Precision developed this antenna to be the perfect companion to the wildly popular 40/30/20m Mountain Topper QRP transceiver. The EFT-MTR’s total length is 65′ of 22 AWG polystealth wire and weighs less than 4 ounces! It is built with the same high level of workmanship and quality that you have come to expect with all EndFedz ® antennas.

A particular innovation on this antenna: This EndFedz is a little different than previous designs. The user has the option to remove an SMA connector at the end of the 30M resonator to enable just 30 meters, or keep the SMA installed for 40 and 20 meters. Because of the broad bandwidth of the antenna, it is unlikely that it will require tuning in the vast majority of deployments. This is particularly true of 30 meters where the band is very narrow. As our tagline states, “They Just Work!”

Included with the EFT-MTR is the EndFedz Antenna Winder. Conveniently allowing winding up the antenna line to not have a tangled mess at the end. The winder will hold both the antenna and 25 feet of RG-174U coaxial cable (optional accessory).

Scott offered to send me an EFT-MTR to evaluate in the field (disclaimer: at no cost to me) and I accepted without hesitation, of course!

An EFT-MTR field review

I’ve taken the EFT-MTR antenna to three park activations at this point and have formed some opinions about it.

The EFT-MTR fits perfectly in a slide-in pocket in the main compartment of the Boot Boss.

First of all, I couldn’t be more pleased with the size as it fits perfectly in my MTR-3B field kit built around my Red Oxx Booty Boss pack.

I really like the built-in antenna winder: it’s larger than that of the EFT Trail-Friendly, but also much easier to wind up and manage post-activation.

I’ll admit, the length of the EFT-MTR was a bit surprising the first time I deployed it: 65 feet.  Keep in mind, though, I had been used to a much shorter 41 foot radiator on the EFT Trail-friendly. Occasionally, I operate in spots where I simply don’t have the room to deploy a long antenna. I also worried that the EFT-MTR resonance might be negatively affected by winding its way through trees and over a branches. The MTR-3B transceiver does not like high SWR values and has no built-in SWR meter to monitor it. Last thing I wanted to do was harm the MTR finals.

You might be able to spot the feed point of the EFT-MTR at my activation of K-6952 this week.

Fortunately, winding its way through trees doesn’t seem to have a significant impact on SWR.

Each time I’ve taken the EFT-MTR to the field, I’ve also taken my KX2 which I’ve used to read the antenna’s SWR value. So far, the difference has only been negligible and SWR well within the tolerances of the MTR-3B.  Score!

I should note here that since I’ve started using an arborist throw line, I’m also able to hang antennas much higher than I could before. This has had a huge impact on all of my field activities.

Removing the SMA cap changes the EFT-MTR from a 40/20 to a 30 meter resonant antenna.

To be resonant on 40, 20 and 30 meters, the EFT-MTR requires a field modification. On the coil about 2/3 the way up the antenna, there’s an SMA connector with a small screw on cap (see above). When the cap is on (thus completing the connection) the antenna is resonant on 40 and 20 meters. You must remove the cap for it to be resonant on 30 meters.

Since I’ve been using the EFT-MTR, I start an activation on 40 meters (which is typically my most productive band), then move to 20 meters (typically, my least productive). If I have the time, or need the extra contacts to confirm a valid activation, I lower the antenna, unscrew the SMA cap, and raise the antenna again.

I thought at first this would be a major pain, but it hasn’t. Now that I’m using an arborist throw line, it’s super easy to lower and raise antennas. But even when I’ve used fishing line, it really hasn’t been an issue.

The only issue I see is I’m afraid I’m going to lose that little SMA cap in the field. To prevent this, I’ve made it a routine to immediately put it in the internal zippered compartment of the Booty Boss pack. I might find a source for those caps, though, just in case I still lose this one.

I’ve been very pleased with the EFT-MTR’s performance. I’m guessing it’s actually higher gain than my beloved EFT Trail-Friendly antenna. On my last activation with the EFT-MTR, I knocked out eight 40 meter contacts in about eight minutes during a period of poor propagation. Note that the MTR-3B was only pushing 3 or 4 watts of power.

I then moved to 20 meters where, frankly, propagation was so crappy I didn’t hang out there long. Instead, I lowered the antenna, removed the SMA cap, and started calling on 30 meters. Within a few minutes, I racked up the rest of my contacts.

I was very pleased with how quickly the Reverse Beacon Network picked up my CQs and was thus auto-spotted on the POTA website.


If you own a Mountain Topper MTR-3 series transceiver, I highly recommend the EFT-MTR antenna. As with my EFT Trail-friendly and Par sloper, the quality is top-shelf. I expect the EFT-MTR will last even longer than the EFT Trail-friendly since the winder is so accommodating and the in-line coil is designed so that it doesn’t snag on branches as easily.

I’m looking forward to much more field fun with the MTR-3B and EFT-MTR combo!

Click here to check out the EFT-MTR at Vibroplex.

Click here to check out Vibroplex’s full line of antennas.

Many thanks again to Scott at Vibroplex for sending me the EFT-MTR for evaluation!

A field antenna’s best friend: The amazing arborist throw line

At least 95% of the time I’m playing radio in the field, I use wire antennas and suspend them in trees.

Since I do a lot of park activations for the POTA program, trees are typically very easy to come by and most of the time the park office doesn’t care if I hang an antenna in their tree for a couple of hours.

For years, I’ve been using a heavy steel nut–a nut that would fit a very large bolt–as a weight and attach it to fishing line. I then simply throw the nut into a tree and pray the fishing line deploys properly. I have reasonably good aim, so–on a good day–I typically only need one or two throws/tries to get the fishing line over a branch. On bad days? Well… let’s just not talk about that.

There are some inherent weaknesses in the fishing line/monofilament system:

First of all, I’m lobbing a heavy metal object into the trees. If it ricochets–and it eventually will–it can come back down to earth and land where you might not want it to (for example, on your radio, on your car, or on your friend’s head).  Fortunately, I’ve never hit anything or anyone as I’m careful to clear the area first, but unfortunately, I once had the nut hit a tree and come back down near me. That was a little scary.

Secondly, fishing line isn’t exactly recyclable and you simply can’t use it over and over. I get at most three deployments with a section of fishing line before it gets too stretched and unworkable.

Finally, fishing line is incredibly prone to tangle, especially near the end of the spool.

A Better Solution? The Arborist’s Throw Line

The arborist throw line is no recent innovation. For years, I’ve read recommendations from other ham radio operators who swear by arborist throw lines but I only recently decided to take the plunge after one very frustrating park activation where my fishing line knotted and almost got permanently stuck in a gorgeous tree. I’m very much a “Leave No Trace” kind of guy, so I was incredibly relieved when I was finally able to work the fishing line out of the tree.

When I got home from that activation, I ordered a Weaver Throw Weight and Line and a Throw Line Storage Cube. (Note: these are Amazon affiliate links that support this site.)

Forester Throw Rope folding/collapsible Storage Cube

I once talked with an arborist about throw lines and he stressed the importance of getting not just the line, but also a throw line storage cube. The cube allows you to both deploy and take up the line without any tangles or knots.

All in, I spent about $50.00 US for both.

Preparing the throw line

My arborist buddy gave me an important tip: the throw line needs to be stretched.

As you can see in the photo above, the throw line is packed in a bundle that’s easy to unroll. After you unroll it for the first time, though, the line has a “memory” of all those bends from its life in the package.

You can remove much of the throw line memory by tying one end of the line to a tree and stretching the line to its full length. The line is 150 (or so) feet long, so you’ll need an open space to do this.

The arborist in this video shows how this is done (I’ve queued it to the point in the video where he shows how to do this):


You’ll need to attach the throw line to the throw weight, of course.

There are a number of knots arborists use, but I’m a fan of the slipped simple noose knot. Perhaps it’s because it’s easy to tie even with semi-rigid line, it holds quite well and, most importantly, it’s easy to untie.

Looks like arborists use it too because when searching for an instructional video, the first result was from an arborists’ channel:

Throwing up!

There are a few different ways to launch a throw line into a tree.

Take my advice here: practice at home before you hit the field! It could save you a lot of embarrassment, although, admittedly, my at-home practice sessions gave my wife and my daughters good reasons to chuckle.

I’ve only been using the throw line for a little over a week, so I’m still sorting out which method works best for me. One thing I discovered very quickly, though: no matter which launch method I use, I can send that throw weight into a tree at least 60% higher than I could before.

No doubt, the throw line and weight really put the laws of physics in your favor!

Here’s a great video highlighting different throw line launch techniques:

In practice

I took the throw line to the field today for the first time and I’m very pleased with how effectively it works.

I was able to place my antenna on a much higher branch than I could have otherwise. It took me three tries today, but it had more to do with my poor aim. As with any skill, this will, I think, improve with practice.

The storage cube folds down flat and keeps the line from tangling

Besides the improved antenna height, I love that the line can be used over and over again. Also, it’s strong enough that should it ever get caught in a tree, I can pull it out without the line breaking.

I can also reel in the line at least three or four times faster than I could with fishing line. Simply flake it into the storage cube one foot at a time.

When the line has been stored along with the throw weight, you can fold the storage cube down flat, then fold and secure it into a compact triangle.

Are there any negatives with the throw line system? Here are a few I’d note:

  • Bulk. Even when packed down, the line in the storage cube take up much more space than fishing line. Although it easily fits in even my smallest backpack (the GoRuck Bullet), I’m not sure I’d take it on a long hike.
  • This system requires a little practice and skill–you can’t pull it out of the package for the first time in the field and expect perfect line launches.
  • The throw line is more conspicuous than fishing line. If you’re trying to be a bit stealthy–as many of us are these days during the Covid-19 pandemic–the bright yellow throw line will attract more attention and questions from other hikers/campers, etc.
One happy activator!

Even though it’s bulky by my standards, I see the throw line becoming a permanent part of my field kit and I expect I’ll use it on most of my POTA activations.

Have you been using a throw line to hang field antennas? Or do you use a different system?  Please comment!