Tag Archives: Mountain Topper MTR-3B V4 Currahee

Steve’s MTR3B-V4 Field Kit in a Rothco Shoulder Bag

June 2, 2025 Thomas Witherspoon 7 Comments

Many thanks to Steve (KV4AN), who shares the following article about his portable field radio kit, which will be featured on our Field Kit Gallery page. If you would like to share your field kit with the QRPer community, read this post.

KV4AN’s MTR3B-V4 Field Kit

by Steve (KV4AN)

The convergence of Solar Cycle 25, lots of great new equipment offerings, many active participants in Parks on the Air (POTA), Summits on the Air (SOTA), and compatible family outdoor activities make this a great time to be a portable High Frequency (HF) QRP ham radio operator. To take advantage of this happy situation, I was recently able to purchase a MTR3B-V4 “Currahee” Mountain Topper transceiver, shown in figure (1). The MTR3B-V4 is a miniature three band (40, 20, and 15 meters) CW only QRP transceiver made by LNR Precision.

Figure 1. MTR3B-V4 “Currahee” QRP Transceiver.

Naturally, I had to form a kit around the new radio. My three goals for the kit were: small size, lightweight, and self-contained. Let’s see how I did. You can comment below if I left something out or if there’s a better choice.

The kit consists of the following items, as shown in figure (2)–links to these items are at the bottom of the page:

MTR3B-V4 “Currahee” Transceiver – 40, 20, and 15 meter QRP CW Transceiver.
Custom Faceplate Cover – A practical and reasonably priced custom faceplate protective cover. I accidentally ordered the cover for the previous version of the radio, but Joshua had no problem with me changing the order to the new one.
Morse Code paddle – This is a reasonably priced paddle with a fairly good feel that I had lying around when the capacitive knobs didn’t work out. I plan to replace it in the future with the CW Morse SP4 POTA/SOTA N0SA design paddle, which is smaller and field proven.
3.5mm Stereo Cable – A 1.5 foot, 3.5mm to 3.5mm stereo (TRS) cable.
Koss Earbuds – Nice quality stereo earbuds.
Earbud Cord Organizer – I hated to add the extra item, but I got tired of untangling the wires of my earbuds. This clever item has solved that problem and is color coordinated with the slick line.
All-Weather Notebook – All-weather notepad for copying QSO information in the field.
Miniature Pen – This is a miniature pen that says it writes on waterproof paper. It will also write upside down, although that may not be a feature you need during normal activations.
Koss In-line Volume Control – An in-line volume control for use with the earbuds. The MTR3B-V4 has a rudimentary volume control, primarily used to set the maximum volume level.
Battery Pack Pouch – A small pouch that perfectly holds the battery pack and keeps all the components together and protected. If you use Icom BP-307 or BP-272 battery packs, they fit perfectly too.
Battery Cell Holder – An eight “AA” cell holder with a 9V-style clip. Eight “AA” NiMH batteries will provide a nominal 9.6V to the transceiver.
AA NiMH batteries – Eight 1.2V “AA” NiMH 2800 mAh Low Self Discharge (LSD) battery cells.
9V Snap Clip – These are good quality 9V snap connectors that also have the coaxial power connector required by the MTR3B-V4 already attached. They are more durable than the ones with exposed thin red and black wires.
Coaxial Adapter – SO-239 to BNC adapter for use when using other antennas with coaxial cables which have a PL-259 connector.
Reliance EFHW “Bugout” Antenna – A very small and sturdy 40, 20, 15, and 10 meter End-Fed Half Wave (EFHW) resonant antenna.
Slick Line – High visibility slick line, which ties to the arborist throw bag to get the antenna into a tree and then suspends it.
Arborist Throw Bag – A well-made arborist throw bag with a good all-around weight.
Gerber Mullet Keychain – An all-in-one minimalist tool kit. Better than a sharp rock, as they say.
Rothco Shoulder Bag – A military-style shoulder bag, just large enough to hold all the kit components.
Battery Charger – The battery charger (not shown) is an eight cell NiMH charger. It does not fit in the shoulder bag and is left at home.

Of course, it all had to fit in a tacticool bag. I selected the small Rothco Excursion Organizer, The shoulder bag, shown in figure (3), has all the items from figure (2) in it (trust me). Use the orange pen as a reference for the size of the bag. Clipped to the “D” ring on the left side is the Gerber “tool kit”. The pocket on the front left has the CW Morse paddle, the pen is in its place, and the zippered pocket on the right has the earbuds. The back zippered pocket has the antenna and battery pack, and safely nestled in the main area is the MTR3B-V4 and an arborist throw bag. There is a zippered sleeve in the main pocket that contains the cable for the keyer paddle, an adjustment Allen wrench, and the SO-239 to BNC adapter.

Conclusion

One thing you may have asked yourself is why I included a Morse Code paddle when the MTR3B-V4 has a set of capacitive touch knobs. The answer is simple – they didn’t work for me. I really wanted them to, but the pad of my thumb will not activate the “dit paddle” without moistening it first. Even then, I have to press the knob hard at a point almost to the joint, which is not a natural code sending motion or feel and results in very sloppy code.

Another item I purchased, but decided not to use was a pair 9V 500 mAh Lithium Ion rechargeable batteries. The voltage of this battery right off the charger is below the specified input voltage for the MTR3B-V4.

The battery is the area in which I am most concerned. I’m concerned that the 9.6V NiMH pack may not provide enough voltage over an activation to keep the voltage above the specified minimum voltage of 9V. I may have to go to a 12V LiFePO4 battery, but that will not fit in the current shoulder bag. I may have to go with a larger bag or use a MOLLE system where I can strap together several pouches.

I think I’ve came close to achieving my three goals of: small size, lightweight, and self-contained. I’ve not completed an activation with this kit yet, so I’ll see how it all works together in a few weeks. I’m also looking forward to reading your comments and suggestions.

72,

Steve

KV4AN

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News, QRP Radios

New MTR-3B V4 Manual Now Available on LNR Precision Website

May 24, 2025 Thomas Witherspoon 3 Comments

If you own the popular MTR-3B V4 transceiver, you’ll be pleased to hear that a new and greatly improved manual is now available on the LNR Precision website.

If you’ve recently picked up an MTR-3B V4—or if you’ve had one for a while and want clearer documentation—I highly recommend grabbing this updated guide.

Click here to view or download the new manual.

Field Reports, Morse Code, New Products, News, Portable, POTA, QRP, QRP Radios, Videos

Chilly Morning, Hot Pileups: Testing the New MTR-3B “Currahee”

January 24, 2025 Thomas Witherspoon 12 Comments

In late December, I received a much-anticipated package from LnR Precision: my new MTR-3B V4 “Currahee.”

Life has been hectic, so I didn’t get the opportunity to take it to the field until Thursday, January 9, 2025, when I carved out some time in my schedule.

It was a chilly morning, with temperatures hovering around 20°F (-7°C). Still, I wanted the full field portable experience with the new Currahee, so I bundled up in my winter gear and headed out.

Pisgah National Forest

Rather than doing another activation on the Blue Ridge Parkway, I checked the Pisgah National Forest website and was pleasantly surprised to find that the Lake Powhatan recreational area was open.

When I arrived, the park employee at the entrance gate informed me that I was the only guest that morning. And what a morning it was! Despite the cold, the clear skies and full sunshine made it a glorious day.

The best part? No competition for picnic tables! Woo hoo! (We must embrace the positives, right?)

Quick field kit

About 10 minutes before leaving the house, I hastily put together a quick field kit for the Currahee in my Pelican Micro M50 waterproof case.

This was a trial run to see how I might organize a fully self-contained kit for the Currahee, similar to what I’ve done for my other MTR-3B radios. While I didn’t have time to finalize all the kit components, I wanted to gauge the space available and determine what antenna, throw line, and other accessories would fit best.

Tufteln Cover

Joshua (N5FY), a good friend, sent me a package over the holidays containing some of his latest Tufteln protective radio covers. To clarify, these were gifts; I didn’t pay for them. Among the covers was a brand-new design specifically for the Currahee.

Like all of his covers (you’ve probably seen the ones I use for my KX2, KX1, CFT1, QMX, and others), this one fits brilliantly. In fact, it might be my favorite! The Currahee cover provides a durable, low-profile solution that complements the radio perfectly. Makes it a very durable little package.

Break-In Activation

In the near future, I plan to create a more in-depth video about the Currahee, but my goal for this outing was to get it on the air and give it a solid break-in.

Although the Currahee features built-in capacitive touch paddles, they require contact with bare skin. I wasn’t keen on exposing my fingers to the cold, so I opted to use my trusty TP-III paddles instead. By the end of the activation, my fingers were still getting sluggish, but I managed to log plenty of QSOs.

For audio, I paired the Currahee with my Anker Soundcore Mini speaker and connected it to a 40-meter End-Fed Half-Wave antenna. This antenna is an ideal match for the Currahee since all three of its bands—40, 20, and 15 meters—are resonant. Kudos to LnR and Steve for these excellent band choices!

For power, I used my 9V Bioenno battery. While the Currahee can handle over 13VDC (making it compatible with a “12V” LiFePO4 battery), I prefer running my Mountain Toppers with 9V, which yields about three watts of output power.