Lunch Box POTA: Pairing the Elecraft AX1 with the Penntek TR-45L!

As I mentioned in previous posts, I’ve been using the Elecraft AX1 in heavy rotation this year. I made a commitment to myself to do a string of activations with it in January and February and also pair it with a wide variety of radios beyond the Elecraft KX2 and KX3.  So far, I’ve paired the AX1 with the:

In truth, the AX1 can be paired with any radio when you use a tripod mount.

It’s a bit trickier when connecting the AX1 directly to a radio and using the Bipod as a support because 1.) the antenna connector on the radio mustn’t be too high off of the surface, 2.) there needs to be enough clearance on the back of the radio to accommodate the bipod legs and 3.) ideally, it’s nice to have a ground point on the radio, else you’ll need to clamp the counterpoise to the shield of the BNC connector.

In addition, if your radio doesn’t have a built-in ATU of some sort, then you’ll also need a capacity hat or external ATU to finish off the impedance match. (For more notes about the AX1 and AX2, check out this previous post.)

Of course, you don’t have to use Elecraft’s bipod to support the AX1 when directly connected to a radio–you can build or 3D print your own support–but the bipod is really convenient when it does work.

Objective: Lunch Box Radio

One radio I’ve been eager to pair with the AX1 is the Penntek TR-45L.

Why? Because I love the form-factor.

Something about having a lunch box-sized radio sitting on a table with a telescoping whip protruding out the back and, with that combo, the potential of making contacts all over the globe.

As a kid, I could imagine some Cold War spy setting up a radio like this, say in some remote part of eastern Siberia, and passing along intel in encrypted CW with an outpost in Alaska across the Bering Strait.

Yeah, I had/have a pretty healthy imagination!

If I’m being honest, I would have attempted to pair the TR-45L with the AX1 much earlier, but frankly I was over-thinking things and making too many assumptions.

The first assumption was that the TR-45L’s BNC connector would be too high for the bipod to work. When I actually connected the AX1 though? I discovered it worked perfectly well.

The bipod legs aren’t at an ideal angle for maximum stability (thinking center of gravity), but on a calm day, it would be very secure, actually. I know I could attach extra support somewhere on the back of the radio, else on the handle to secure the AX1 better if needed.

And it really looks the part!

The next challenge would be finding a grounding point for the counterpoise. While I could always clamp a counterpoise onto the outside of the BNC connector, I wanted a more elegant solution.

The TR-45L has both a BNC connector and binding posts for balanced line. I thought it would be very convenient to be able to use one of the binding posts, but by its very nature, I assumed it would not have one side connected to ground like, say, the BNC port.

I opened my junk drawer and found a small, low profile lug that would work perfectly as a grounding point. My plan was to drill one small hole in the back of the TR-45L, install the lug, and connect it to ground inside the radio. This would be an extremely simple mod.

I literally had the drill in my hand and paused, thinking, “maybe I should ask John (WA3RNC) if, by chance, one of the binding posts was connected to ground with the BNC engaged or at least ask about the best place inside the radio to make the ground connection?”

I shot a quick message to John and his answer surprised me:

On current production units, the black bananas jack is at ground when the [antenna] switch is in the coax position. I don’t remember if I paid much attention to the color of the banana jacks on the early prototype units, because for balanced operation it doesn’t much matter. So, it is possible that it might be the red one that is grounded instead of the black one [on earliest production models like this prototype]. 

I tested the black post and, sure enough, when the BNC port was selected, the black post was connected to ground! (Why didn’t I test this initially?) I also sent John a photo of the Z-Match and antenna post wiring and he also confirmed the black post was grounded.

How incredibly convenient!

I put the ground lug back in the junk drawer for a future project!

The only other lingering question: can the TR-45L’s Z-Match ATU achieve an acceptable SWR? Only way to find out was to take this radio package to the field!

Blue Ridge Parkway (K-3378 NC)

On Tuesday, February 7, 2023, I dropped my daughters off at a class, then made my way to the BRP Folk Art Center for a late morning activation.

The weather was beautiful and there were very few people at the center, save some construction workers doing winter projects.

Setting up the TR-45L couldn’t have been easier.

Since my TR-45L has a built-in speaker, battery and tuner, there were no other accessories other than my paddles and the AX1.

I attached the AX1 to the BNC port and the 13′ counterpoise to the black binding post.

What a handsome pair–!

The Begali Traveler made the field kit look the part, too.

I actually don’t care what radios look like; performance and ergonomics are much more important. What I think makes the TR-45L such a gem of a radio is that its form following function: it has excellent ergonomics, excellent performance, and some serious Apollo era aesthetics.

Next, I tuned to a free frequency on the 20 meter band, sent a steady CW tone and achieved a near perfect SWR using the Z-Match tuner. Woo hoo!

Note that I was careful not to touch any of the conductive part of the AX1 while keying down. Even though the TR-45L was only pushing 5 watts, you’d feel a little RF I’m sure! Fortunately, the clear plastic tube pretty much protects your knuckles as you make the adjustments to the L and C controls.


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On The Air

I hopped on the air and started calling CQ POTA. Within a minute, I was answering hunter calls at a good pace. I logged my first ten contacts in ten minutes thus validating this activation.

Side note: I remember in the early days of POTA, getting “your ten” was the main goal and not always easy to accomplish. I clearly remember activations that took well over an hour to log ten POTA hunters. Keep in mind that the POTA community was a teeny fraction of the size it is now and propagation was much worse. In those early days, CW hunters and activators had a strong bond because there were so few of us out there. Hunters would routinely work you on every band and mode they could to help you “get your ten.”

I continued calling CQ POTA for another twenty minutes, effortlessly logging a total of 25 stations.


Here’s what this 5 watt activation looked like when plotted out on a QSO Map. One thing I noticed immediately was how short the 20 meter band was that morning. The QSO Map looks more like what I would expect to log on 40, or possibly 30 meters. I imagine the band was much longer later in the day.

Activation Video

Here’s my real-time, real-life video of the entire activation.  As with all of my videos, I don’t edit out any parts of the on-air activation time. In addition, I have monetization turned off on YouTube, although that doesn’t stop them from inserting ads before and after my videos.

Note that Patreon supporters can watch and even download this video 100% ad-free through Vimeo on my Patreon page:

Click here to view on YouTube.

Achievement Unlocked: The AX1 + TR-45L = Serious POTA Fun!

If you happen to own both a TR-45L and an Elecraft AX1, I would encourage you to pair them on your next POTA or SOTA activation. Double check to make sure which binding post is connected to ground in advance.

As I mention in the video and above, I find there’s something magical about operating a radio with this “lunch box” form-factor.

Having cut my teeth as an SWL with a Zenith Transoceanic, I often dreamed what it would be like if that radio could also transmit and I could make contacts all over the world.

This, in many ways, feels like that childhood dream fulfilled! What fun!

Thank you

Thank you for joining me on this activation!

I hope you enjoyed the field report and my activation video as much as I enjoyed creating them.

Of course, 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.

As I mentioned before, the Patreon platform connected to Vimeo make it possible for me to share videos that are not only 100% ad-free, but also downloadable for offline viewing. The Vimeo account also serves as a third backup for my video files.

Thanks for spending part of your day with me! Here’s wishing you an amazing weekend ahead!

Cheers & 72,

Thomas (K4SWL)

14 thoughts on “Lunch Box POTA: Pairing the Elecraft AX1 with the Penntek TR-45L!”

  1. Thank you for that report, Tom! That was like poetry!
    What a combination; TR-45, Traveler, AX1, beautiful weather!
    I’m going to read this again on the weekend, and watch it too.

  2. I so enjoy reading your blog
    I was wondering if you seen or experienced using the MMX Multi-Band Morse Code Transceiver? And what your opinion of encoder/decoder’s?
    I’m interested in working qrp but I have serious hearing issues. I know there are digital modes I can use , but I like the low power radios.
    73, N9ztn

  3. Thanks, Thomas for another great write up and the very fun pairing of radio and antenna! I’m about 1.5 months into my wait after placing my order on this rig. I know the anticipation is half the fun on getting new gear, but hoping to see an email that it’s ready to ship sooner than later… 🙂

    I think I’ve watched every video on YT on this cool radio, so seeing that you had posted a new one this morning was a great way to start the day.

  4. Yet another fine post. My AX1 has arrived already. Still waiting for the TR-45, esp since hearing all of your fine reports about both of these. Thanks for the reports Thomas!

    Regarding the N9ZTN reference to hearing problems. I too have had hearing damage and wear hearing aids. Today’s hearing aids are marvelous; most all have built-in Bluetooth. So, put a Bluetooth xmtr in the phones jack and pipe that sound directly into the hearing aids. It works great for all sorts of audio. Soon, I’ll see if it works well with the TR-45. I’m slightly apprehensive since the plug-in Bluetooth xmtrs have some latency delay, and I don’t yet know if they’ll keep up with keying. But hey, at less than 12 wpm the latency might not matter. 🙂 (I’m still in the Morse rehab program.)

  5. Michael, you will love it. I keep it in the car and ready for an activation when the opportunity presents itself.

  6. You wrote “the antenna connector on the radio mustn’t be too high off of the surface”.

    If it is, just put one or more books underneath the bipod legs.

    David VE7EZM and AF7BZ

  7. Great review Thomas, the Begalli key and TR-45 go together so well (and sit on my radio desk next to my KX3/PX3 combo. Having a TR-35 didn’t envisage using the TR-45 in the field, but after watching this video….

    As for the AX1, I’m a huge advocate, it has allowed me to operate in so many places that I wouldn’t have normally been able to. It sits as part of my potable field kit alongside my KX2.

    Not sure you’ve tried it yet (my apologies if I missed that one) but the AX1 works fabulously with the KX1 too! If you haven’t tried that I’d highly recommend it.

    And yes, I’m a bit of an Elecraft KX and Penntek TR series fan!

    Richard M0RGM

    1. You know, as I finished the field report yesterday it hit me that I hadn’t pair the AX1 and KX1! I’ll be doing that next! 🙂

      Thank you,
      K4SWL / M0CYI

  8. “One thing I noticed immediately was how short the 20 meter band was that morning.”
    That’s something I’ve noticed frequently when I use a compromise antenna like a magloop. When I switch to a wire or a full-size whip, the distance doubles or triples. I could speculate on the propagation mechanics, but I don’t really know for sure.

  9. Thank you for sharing this activation Thomas!
    I was delighted to see my callsign in the log (WD4MSM) for February 7.
    It’s great to see your setup and the nice Carolina weather (it’s still winter up here in northern Indiana!).
    The Penntek you used shows up well in both the pictures and the excellent audio; that is one handsome radio with an internal battery and antenna tuner.

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