All posts by Thomas Witherspoon

QRP DX: Pairing the MM0OPX EFHW & Icom IC-705 during an impromptu activation

Turns out, if you go to Canada for nearly two months, when you return home you’re going to have about two months worth of catch up .

It’s all explained in one of Einstein’s theories. If memory serves, Einstein stated:

“One cannot simply ignore stuff for two months and expect no repercussions. Time lost must be accounted for due to the principles of the conservation of energy. Plus…what in creation were you thinking?”

When we returned from Canada in early August I had some pretty big plans about the parks and (especially) summits I would hit here in North Carolina. But after returning, I quickly realized I had so much work to do around the house and a number of DIY jobs I’d postponed at our investment property. They all immediately took priority.

Indeed, in the one month span after returning from Canada, I only performed three park and no summit activations. There was a three week period of time without activations of any sort. I simply didn’t have the time to fit anymore in my schedule. This all gave me a serious case of activation withdrawal.

If you’ve been following my field reports, you’ve no doubt noticed that I never do multi-hour activations at one site unless I happen to be camping at a POTA park.

I’m asked about this fairly regularly (why I don’t do longer activations to achieve Kilo awards, etc.) but the truth is I make POTA/SOTA fit in my busy family schedule. This often equates to short (30-60 minute) activation windows.

Then quite often, I’m on the road or doing errands in town and realize I have a short opening for an activation, so I squeeze it into the day. This is why I always have a fully self-contained field radio kit in my car. At a moment’s notice, I can set up a station, and play radio.

In a way, I find this style of quick activation fun, too. “Can I seriously validate a park during this short window of time–?”

These activations remind me of that scene in A Christmas Story where the father get’s a small thrill out of timing himself as he changes a flat tire on the side of the road. I totally get that.

Except with me it’s deploying antennas instead of managing lug nuts.

Hamfest time!

Friday, September 2, 2022 was a big day for me. On the way back from visiting my folks that morning, I spent a couple of hours at the Shelby Hamfest.

The Shelby Hamfest typically has the largest outdoor tailgate market in all of North Carolina and likely one of the larger ones in the southeast US. I had no items on my wish list, I just wanted to see what was there.

This was the first hamfest I’d attended in a little over a year. It was a lot of fun and I got to meet a number of friends and readers/subscribers.

If you’d like to see the treasure I found at the Shelby Hamfest, by the way, check out the large photo gallery I posted over on the SWLing Post.

Back to the topic of impromptu activations…

South Mountains State Park (K-2753)

Driving home after the Shelby Hamfest that early afternoon, I realized I was passing dangerously close to the Clear Creek access of South Mountains State Park.

I had a couple of errands to run back home before the post office closed at 17:00 that day, but in my head I believe I had just enough time for a quick activation. The total amount of detour driving would only be about 15 minutes; I’d just need to keep the activation (including most set up and pack up) under 45 minutes or so.

At the last minute, I took a right turn and headed to the park!

Fortunately, the one lonely picnic table at the Clear Creek access was unoccupied.

I grabbed my IC-705 kit and a new antenna!

The MM0OPX QRP End-Fed Half-Wave (EFHW)

A few weeks prior, Colin (MM0OPX) reached out to me and asked if I would consider testing a new high-quality, highly-efficient QRP EFHW he’d designed.

Of course, there’s nothing new about an EFHW–it’s one of the most popular field antenna designs on the planet–but Colin’s goal was to make one with the lowest insertion loss possible in a compact, lightweight (50g), and durable format.

I say he succeeded.

In fact, this activation was actually the second one where I used Colin’s QRP EFHW. The previous day, I paired it with a then very Beta version of the Penntek TR-45L at Tuttle Educational State Forest (K-4861).

In short, the antenna made for a wildly successful QRP activation. Here’s the QSO Map (you’ll need to click and enlarge to see the number of contacts):

QSO Map from the previous day with the MM0OPX QRP EFHW

The Penntek TR-45L was still quite new at the time and even though  I got John’s (WA3RNC) blessing, I didn’t post the activation video and mini overview on YouTube. Keep in mind the TR-45L was still in Beta so not all features had been finalized.

I did, however, post the entire TR-45L activation video on Patreon.

Quick side note: Why this video only on Patreon?

As I mentioned in a previous post, I’ve now invested in a Pro account with Vimeo that allows me to post completely ad-free videos  that my Patreon supporters can enjoy and even download. I recently discovered that YouTube unfortunately inserts ads even though I have monetization turned off. I pay for Vimeo’s bandwidth and server space, so I also can control the ad experience completely (basically eliminating any possibility of ads!).

My Patreon supporters are the ones making it possible for me to pay the annual $420 fee to Vimeo and I am incredibly grateful, so I pass along the benefit to them.

Continue reading QRP DX: Pairing the MM0OPX EFHW & Icom IC-705 during an impromptu activation

The FX-4L QRP SDR HF transceiver is on order!

This year, I’ve had a couple of readers very kindly offer to loan me their FX-4C transceivers to take to the field and review.

Those offers have been very temping because I’ve only heard positive comments from owners of this wee feature-packed SDR transceiver designed by Yu (BG2FX).

Earlier this year, I learned that Yu was retiring the FX-4C and would be introducing two new radios, so I decided to hold off on an FX-4C review for this reason.

My buddy, Don, informed me that the new radios were now available for pre-order, so I checked out the option on Yu’s website, and placed an order.

Details (features and specs) are still a little sparse because BG2FX is still finalizing the design and lining up production, but here’s a snapshot of the two models based on Yu’s preliminary info:

The FX-4CR

I was very pleased to read that my buddy John (AE5X) has one of these on order.

The FX-4CR can push 15-20 watts on most bands according to John, which is most impressive for a one pound radio that fits in the palm of your hand! It covers 80 – 6 meters, sports a color screen with a 48 kHz wide waterfall display, an internal sound card for digital modes, built-in speaker and microphone, 9 – 18 VDC input range, and even sports Bluetooth!

That’s an impressive array of features for $550 US (on pre-order).

The FX-4L

I pre-ordered the FX-4L and am told by Yu that it should ship by end of October or early November 2022. I wouldn’t be surprised if that’s an optimistic projection.

The FX-4L is essentially a more basic QRP version of the FX-4CR; it’s maximum output power is around 5 watts.

It’s very similar to the FX-4CR in many respects: it has the same display from what I can tell, covers 80 – 6 meters, has a wide voltage range 9 – 18 VDC, sports an internal sound card, and is super compact and lightweight.

The FX-4L doesn’t appear to have Bluetooth. Lu doesn’t mention a built-in speaker or microphone, but there’s an obvious speaker grill and even a small hole that might be a microphone. I’ll try to confirm this. Yu does note that there’s room in the chassis for the user to add a battery or ATU.

I’ve been more interested in the FX-4L because, as you likely know, it’s very rare for me top operate over 5 watts of power.

That said, I certainly see the appeal of a 15W+ radio like the FX-4CR.

(Many thanks to Yu for sharing all of the FX-4L photos above.)

Stay tuned!

I’m really looking forward to checking out the FX-4L and also reading AE5X’s assessment of the FX-4CR.

I’m curious if anyone else has pre-ordered one of these radios. Also, if you’re an FX-4C owner, I’d love to hear your comments!

What are my favorite QRP field radios in terms of audio quality–?

Many thanks to QRPer.com reader, Charles, who recently sent me the following question:

Thomas, I’ve watched a number of your videos and read your activation reports. I’m studying for both my Technician and General class license right now and hope to pass both in one session later this month. I’m also learning CW.

I consider myself an audiophile and appreciate good audio fidelity. I know that amateur radio modes are narrow and by their very nature have less audio fidelity than commercial broadcast modes. 

I’ve already obtained a Kenwood TS-590G for the shack. It was practically given to me by a friend. I’m very pleased with its audio fidelity especially when I connect it to an external speaker.

Next year, I plan to buy a dedicated QRP field radio. Out of the radios you’ve owned, what are your favorites in terms of audio fidelity. Also, what are your least favorites?

Thank you.

What a great question, Charles!

Being an audiophile, I’m sure you understand that this is a very subjective area: one person’s idea of good audio might not match that of someone else’s.

I can only speak to how I evaluate a transceiver’s audio.

What makes for good audio?

A lot goes into what I would call “good audio” in an amateur radio transceiver.

To me, “good audio” means the radio

  • produces clear accurate sound,
  • has stable AGC (Auto Gain Control),
  • has audio properties that benefit amateur radio modes like CW and SSB,
  • has enough audio amplification to be heard in noisy field conditions,
  • and has little to no internally-generated noises leaking into the audio amplification chain. (In other words, a low noise floor.)

In contrast, radios with poor audio

  • sound noisy/harsh,
  • have a high noise floor or produce audio hash making it difficult to hear weak signals,
  • have speakers that become distorted at higher volume levels,
  • have poor AGC characteristics which lead to pumping,
  • and are simply fatiguing to listen to during extended on-air sessions (like long activations or contests).

I would add that a good receiver front end is an important part of audio because it keeps imaging and overloading at bay, thus producing a less cluttered and noisy audio experience.

My field audio favorites

I’ll keep this discussion limited to QRP field portable radios. There are numerous 100 watt desktop radios with excellent audio because those models aren’t trying to limit their current consumption like field radios typically do. They can use more amperage to benefit audio amplification and push a much larger speaker.

In addition, I’ll limit the scope to field radios with built-in speakers. There are some great CW-only radios out there that lack an internal speaker but have great audio (thinking of the Penntek TR-35 and the Elecraft KX1, for example); choice of earphones or headphones can have a dramatic effect on audio. That’s a different discussion altogether!

Best audio: My top three picks

The following are three of my favorite portable field radios in terms of audio quality. I limited myself to three simply because all of the radios I use regularly in the field have what I would consider good and acceptable audio.

The following are simply stand-outs, in my opinion:

Continue reading What are my favorite QRP field radios in terms of audio quality–?

Taking the Mountain Topper MTR-4B on a quickie activation at South Mountains State Park!

The entire time I was in Canada this summer–about two months–I  used two field transceivers: the Elecraft KX2 and the Discovery TX-500.

I did sneak in two extra radios under the floor of my trunk/boot space, but they both were limited to three watts and conditions were so rough during many of my activations, I wanted the option of a QRP “Full Gallon” (5 watts). Thus, I stuck with the TX-500 and KX2 (which are both actually capable of 10 watts output).

When I got back to the States, I was eager to do a POTA activations with my other radios–many of you know I like to rotate them–but there was one, in particular, I was eager to put back on the air…

The Mountain Topper MTR-4B.

This MTR-4B V2 is on loan to me from a very generous reader/subscriber. In fact, get this: he ordered the MTR-4B early this year and had it drop-shipped to me directly from LnR Precision. He knew I’d be in Canada for the summer, so has been incredibly flexible with the loan period (basically leaving it open ended).

My review of the MTR-4B will be published in the November or December (2022) issue of The Spectrum Monitor magazine. Then I’ll be sending the MTR-4B to its rightful owner!

In the meantime, I built an ultra- compact field radio kit around the MTR-4B and in my Tom Bihn HLT2 EDC pouch.

This kit is nearly identical to the one I made for my MTR-3B (just a different color, really).

It contains the radio, a battery, an antenna (although I used a different one during this activation), fused power cord, paddles, earphones, RF choke, RG-316, logbook, pencil, and even a full throw line and weight. I’ve listed all of the components with links below.

It’s hard to believe it all fits in such a compact kit and it works so well. It’s nice to know that with the kit it in my backpack, I’ve got everything I need to play SOTA or POTA at the drop of a hat.

South Mountains State Park (K-2753)

On August 8, 2022, I drove to my hometown to check in on my parents. I didn’t have a lot of time, but I wanted to fit in a quick activation with the MTR-4B along the way.

One of the easiest parks for me to hit en route is the South Mountains State Park Clear Creek Access–it’s maybe a 10-15 minute detour off of Interstate 40.

The weather was amazing that day, although I’ll admit I had to get used to the heat and humidity after spending so much time in Canada this summer!

This access point of South Mountains only has one picnic table. I’m always prepared with a folding chair if that table is occupied, but so far it’s always been available. I’m sure the reason is because this particular South Mountains access point is way less popular than the main entrances. Most of the visitors here come to fish at the reservoir.

Setting up

The great thing about having your whole station in a pouch is that setup is quick and easy.

Continue reading Taking the Mountain Topper MTR-4B on a quickie activation at South Mountains State Park!

The New Penntek TR-45L: A Video Tour/Overview, then a full POTA activation!

Yesterday, John (WA3RNC) opened orders for his long-awaited Penntek TR-45L 5 band, CW-only, QRP transceiver.

As I mentioned yesterday, I’ve had the pleasure of helping John beta test this radio for the past month. In that time, I’ve gotten to know the radio from the inside out and have even taken it on a few POTA activations. In fact, with John’s permission, I just posted my first TR-45L activation video for Patreon supporters yesterday. The radio was using an early firmware version in that video.

TR-45L Video Tour and Overview

Yesterday, after an early morning appointment, my schedule opened up; a rarity in my world.

I then got the idea to take the TR-45L out to a park, do a full video overview of its features, then put it on the air in a POTA activation.

Hazel loved this idea too.

So I packed the TR-45L, a log book, my throw line, and two 28′ lengths of wire. Hazel jumped in the car before I could invite her.

I’ve used a wide variety of antennas on the TR-45L over the past weeks, but I hadn’t yet performed a park activation only using two lengths of wire and relying on the TR-45L’s optional Z-Match manual antenna tuner. This would make for a great real-life test!

Quick note about video timeline

Side note for those of you who follow my field reports and activation videos

I pushed this video to the front of the line since the TR-45L just hit the market. I wanted to give potential buyers an opportunity to see and hear this radio in real world conditions thinking it might help them with their purchase decision.

I’m currently about 7 weeks behind publishing my activation videos. Much of this has to do with my travel schedule, free time to write up the reports, and availability of bandwidth to do the video uploads (I’ve mentioned that the Internet service at the QTH is almost dial-up speed).

I was able to publish this video within one day using a new (limited bandwidth) 4G mobile hotspot.  Patreon supporters have made it possible for me to subscribe to this hotspot service and I am most grateful. Thank you!

So that I can publish this report quickly (this AM), I’m not going to produce a long-format article like I typically do. Instead, this is one of those rare times when the video will have much more information about the radio and the activation than my report.  I’ve linked to and embedded the video below.

Now back to the activation…

Continue reading The New Penntek TR-45L: A Video Tour/Overview, then a full POTA activation!

Introducing the new Penntek TR-45L

If you’re a fan of the Penntek TR-35 or its predecessor, the TR-25, I’ve got some good news for you.

John (WA3RNC) announced this morning that he is now taking orders for his latest design: the long-awaited TR-45 Lite (TR-45L).

I’ve been helping John Beta test this radio since mid-August. I’ve activated a number of parks with it and have used it almost exclusively from home.

In short? I really love it.

Here’s the announcement John (WA3RNC) has posted on his website along with a form to fill out if you’re interested in purchasing from the first run. John notes:

The TR-45L 50-unit pilot run construction is now underway! These first units will be factory wired, tested, and aligned. These units will be available for shipment over the next several weeks. The plan is to have kits available in about 6 to 8 weeks. The kit price is expected to be $430.00. Please understand that this will not be a kit for beginners…

Pricing has been set at $580.00 for wired and tested pilot run units, with an additional charge of $22.00 for USPS Priority Mail shipping. There are two available options: The first is an internal 5200 MAH Li-Ion battery pack and charger with a price of $80.00, and the second is an internal Z-Match antenna tuner for easy matching in the field to simple wire antennas. The Z-Match tuner option is priced at $60.00. Note that the Z-Match ATU can be added later but will require that you drill some rather precise holes in the back case housing and a do a bit of soldering. [Continue reading…]

This radio is pricier than the TR-35, of course, but I would argue it’s very well worth the money: the receiver and audio are superb. The radio has a fun factor that’s hard to describe.

I’ve just updated the radio with the latest firmware and will be taking it on an activation this morning (Monday, Sep 26, 2022). Check the POTA spots page for me.

I’ll make a video including a full tour of the radio, then perform the activation.  If the hotspot bandwidth gods are on my side, I may have this posted later today or early tomorrow.

Note that John (AE5X) has also been testing the TR-45L and will also have updates and videos.

The upshot?

If the TR-45L looks like the sort of radio you’d enjoy taking to the field, just go ahead and get one.  I think it’s brilliant.

I suspect his first production run will sell out in very short order.

It’s a simple radio with simple–almost Apollo era inspired–controls. The audio is gorgeous and I’m pleased with the filtering options. The internal battery option will power it for ages and the Z-match tuner options works beautifully.

Again, if you want to hear it on the air, check the POTA spots for me sometime between 16:00-18:00 today!

Stay tuned!

Biplanes, Canoes, Callsigns, and POTA: Looking back on our summer in Canada and final field report from Québec

Our travels in Canada this summer exceeded our expectations.

Looking back

Les Escoumins, Québec (click to enlarge)

If you’ve been following my Canada POTA activations and field reports, you’ll get an idea where we traveled and a small sampling of the many amazing parks Canada has to offer.

We started off our trip in Ottawa where we spent four days.

Only moments after arriving at our hotel that first day, Vince (VE6LK) made time in his schedule to administer my Canadian Basic exam remotely. That evening–despite being a bit bleary eyed after a fairly long day of driving–I passed my Basic with Honours. (I’m still chuffed about that!)

By the next morning, I already had the callsign I requested: VY2SW. My mailing address in Canada is in Prince Edward Island hence the VY2 call. Since essentially every new call in Canada is a vanity call, I chose the suffix SW to reflect my US call. PEI is one of the few provinces where as a Basic license holder you can request a 2×2 call.

My first activation in Canada was at Hog’s Back Conservation Reserve.  I had the good fortune of meeting up with Andrew, one of my subscribers, at the park. It was great getting to know him–what a nice fellow–and to start off a series of activations in Canada on the right foot.

St-Anne River in Saint-Ferréol-les-Neiges

After leaving Ottawa, we made our way to Saint-Ferréol-les-Neiges, Québec where we’d reserved a condo/townhome for 6 weeks. That served as our home base as we traveled around Québec City, Saguenay, the Charlevoix region, and the North Shore of the St-Lawrence.

At our local farmer’s market in Saint-Ferréol-les-Neiges, I especially loved the VW campervan bookstore.

I noted in many field reports how surprised I was to discover that a number of popular parks were still ATNOs (All-Time New Ones) in the POTA network. Then again, POTA hasn’t been in Canada as long as other similar programs like WWFF and SOTA.

Many of the POTA activations I made in Canada were in urban parks–especially the ones in/around Québec City. These activations took me outside of my comfort zone; I’m used to activating state and national parks back home that are expansive and largely in rural areas.

Continue reading Biplanes, Canoes, Callsigns, and POTA: Looking back on our summer in Canada and final field report from Québec

Sam builds a compact external speaker and 200 Hz filter for the Penntek TR-35

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


A Compact CW Filter and Speaker Build for the TR-35

by Sam Duwe, WN5C

I recently built a Penntek TR-35 and, like seemingly everyone, I love it.

Once the rig passed the smoke test I was having too much fun and wasn’t quite ready to put away the soldering station. I had two non-essential wants for this project: a narrower CW filter for listening comfort, and an external speaker. Here’s a quick description of how I crammed both of those into an Altoids tin. Nothing is new or groundbreaking here, but it has been a fun and useful project for me and hopefully will give some inspiration for others.

The Hi-Per-Mite

The heart of the project is a Hi-Per-Mite 200 Hz CW filter, designed by David Cripe NM0S, and sold as a nice kit for $28 by Four State QRP Group. Hans Summers G0UPL uses the circuit in the QCX so many will be familiar with the filter’s sound. It’s nice and narrow with no ringing, and makes using my base station (a Kenwood TS-520 with the 500 Hz crystal filter) a joy.

To be clear, the existing narrow filter in the TR-35 is great, but I like the option of going narrow(er). It’s a Pixie-level build difficulty so it should come together in an easy couple of hours. I originally built mine in an Altoids tin using inspiration from Phillip Cala-Lazar K9PL’s review and it worked very well. It sips current and is powered by a 9-volt battery. With a DPDT throw switch connected to both the audio path and the power you can easily switch the filter on and off.

The Speaker

A neat aspect of the TR-35 is that there is a lot of audio gain so you can drive a non-amplified speaker. I have a little Bluetooth speaker that does this trick when I want to use CW to annoy people, but I figured if I’m already hauling an Altoids tin to the field maybe I could get it to talk, too. I looked around my junk box and found a broken Baofeng speaker mic and salvaged the speaker. It works really well: a robust but comfortable volume.

I’m sure any little speaker would do the trick… nothing fancy here, it gets hot glued it to the lid of a mint tin after all.

The Build

After I built the Hi-Per-Mite here’s what I did: first I ate a tin of Altoids and felt a little sick. Then I drilled some holes. The one on the left is for the audio input, the one on the bottom for the headphones (both of these are 1/8” stereo jacks), and two on the right for two mini DPDT switches. I also drilled holes in the lid for the speaker sound to come through. I gave the tin a good sanding and tried to remove sharp edges, and then sprayed the lot with black primer and spray paint.

Continue reading Sam builds a compact external speaker and 200 Hz filter for the Penntek TR-35

Activating Plaines d’Abraham in Old Québec with the KX2 and AX1 combo

When we spend the summer in the province of Québec, we always set aside at least one day to hang out in Old Québec. This portion of the city of Québec is simply stunning: it’s a UNESCO World Heritage site and the birthplace of French North America.

No other place in North America reminds me more of the years we lived in Europe than Old Québec.

We’ve been to Old Québec a countless number of times over the past two decades; we enjoy checking out the architecture, the window boxes full of flowers, and the numerous museums.

Old Québec is, of course, quite touristy–especially if you visit on a weekend. It can be incredibly busy and also challenging to find parking especially if, like us, you have a cargo box on top of your car (many parking decks have strict height restrictions).

On Tuesday, July 26, 2022, we decided to make a trip into Old Québec to visit some of our favorite book shops, small businesses, enjoy a lunch together, and soak in some of the amazing weather.

My wife encouraged me to find a nice POTA site and–wow–is one spoiled for choice! There are no fewer than 10 POTA parks in/around Old Québec. Check out the POTA map–each yellow dot is a park:

I know Québec City well enough to know that some of these parks wouldn’t be terribly easy to activate since they’re historic buildings and sites–I think it could be done, but you might need to seek permission in advance. I think it would be incredibly fun to set up a multi-park rove on foot; in fact, I’ve put that on my bucket list for a future trip!

The park I was eager to activate is the largest in central Québec City: The Plains of Abraham. It’s a beautiful and open urban park that overlooks the the St-Lawrence river. It’s Québec City’s version of Central Park.

Plaines d’Abraham (VE-1019)

I was very fortunate: after we dodged a little road construction, I found parallel parking on Ave Winfred-Laurier next to the Parc Jeanne d’Arc.

Continue reading Activating Plaines d’Abraham in Old Québec with the KX2 and AX1 combo

Fold-out feet for the Penntek TR-35

I must thank my buddy John (AE5X) for this excellent tip.

I was watching one of his YouTube videos some time ago and noticed that he added fold-out feet to his Penntek TR-35.

Like John, I appreciate my radios sitting at a bit of an angle as I operate and these fold-out feet looked like the perfect addition to my TR-35.

These feet are designed for laptops which are much heavier than the TR-35 or pretty much any similar field radio.

They arrive in a small package with an alcohol wipe to clean the bottom of the radio. The adhesive pads on the feet are made by 3M and high quality. I doubt they’ll ever fail. Since they’re designed to allow airflow under a hot laptop, I believe the adhesive should withstand hot summer days in the field as well.

Continue reading Fold-out feet for the Penntek TR-35