My first POTA activation with the Mountain Topper MTR-4B V2

As you might have noticed from past field reports, I’m a big fan of the LnR Precision Mountain Topper MTR-3B. It’s a wee CW-only transceiver that is almost perfectly designed for summit and park activating. It’s so lightweight and compact, you barely notice it in your backpack.

Thing is, the MTR-3B is no longer produced and I’m not sure if it ever will be again, but Steve Weber (KD1JB) hasn’t stopped making iterative improvements to the Mountain Topper design and LnR hasn’t stopped producing them.

In late 2020, LnR introduced the new MTR-4B which replaced the MTR-3B and added a few extra features that many of us had been asking for including:

  • Easy access to sidetone volume control (with a dielectric screwdriver)
  • A built-in SWR meter
  • A wider voltage range and higher output power (up to 5 watts)
  • And the 80 meter band in addition to 40, 30, and 20 meters

The MTR-4B also has an attractive red gloss chassis.

And the right and left sides of the chassis even protrude a bit to better protect the front panel buttons and switches when the unit is flipped over on its face. Nice touch!


One of the great things about being me is I am often at the receiving end of incredibly generous people who like supporting what I do. is a pure labor of love and I’d do what I do without any compensation, but it’s an honor when anyone goes out of their way to thank or support me.

Seriously: the kindness I feel here restores my faith in humanity.

In January, a reader (who wishes to remain anonymous) approached me with a deal I simply couldn’t refuse. He is a very seasoned and accomplished field operator but has only recently been upping his CW game. I believe as a reward to himself for starting CW activations later this year, he told me he wished to order a new MTR-4B.

What he proposed was to purchase the radio from LnR and have it drop-shipped to me. He wanted me to have the opportunity to review this little radio and log field time with it as well. He told me I could use it for months before shipping it to him and not to worry about it getting scratched or showing other signs of field use.


I loved this idea because, as a reviewer, it isn’t financially viable to buy each and every radio I would like to review. I do like asking manufacturers for loaner radios, but LnR is a small manufacturer and make these units to order. I know them quite well and they simply don’t have extra loaner units lying around the shop–much like new automobiles these day, each one produced is already spoken for.

I accepted his offer with gratitude. I looked forward to getting my hands on the MTR-4B!

But that wasn’t all: this kind reader has actually been sending me coffee fund contributions that will add up to half the price of a new MTR-4B should I decide to purchase and add one to my own field radio arsenal! I tried, but I couldn’t talk him out of it.

So there you go. I’m so incredibly grateful.


As LnR Precision states on their website, there’s roughly a 6-8 week lead time on the MTR-4B. I took delivery of this unit in early March.

As with all LnR Precision products, it was packed amazingly well.

I wasn’t sure what to expect in terms of size, but the MTR-3B is only slightly bulkier than the MTR-3B (indeed, in my activation video below, I compare the two).

I love the hotrod red paint job!

This unit arrived during what turned out to be a crazy time for me–one where there was nearly a four week period with no field activations. That’s how crazy!

I did play with the MTR-4B in the shack, however, during that time and logged numerous POTA, WWFF, and SOTA activators. I even had a couple of 80 meter rag chews.

Many field ops were surprised that the MTR-4B didn’t use the forth band position for 17 or 15 meters and I tend to agree. In the field, efficient 80 meter antennas are a bit bulky for the likes of a summit activator. Then again, when in the shack or for extended camping trips? I find 80 meters a brilliant band for evening rag chews and late night DXing.

Not sure how much I’ll use 80M in the field, but I do appreciate this additional band!

Of course, the MTR-4B is built for playing radio outdoors and that’s exactly what I had in store for it on April 13, 2022.

Tuttle Educational State Forest (K-4861)

I decided to take the MTR-4B to one of my favorite spots for its maiden activation. I love Tuttle because it has so many brilliant locations to deploy pretty much any type of antenna.

As I pulled into Tuttle’s parking lot, I noticed several school busses. There were at least fifty middle school students in the picnic area listening to the tail end of forestry presentations.

I picked an activation site far away from the school group so I didn’t distract anyone when fishing for tree limbs with my arborist throw line!

You can *just* see the EFHW winder and feed point in this photo!

For this activation, I chose the antenna that happened to be in my backpack at the time: MW0SAW’s 40 meter end-fed half-wave.

Since the MTR-4B has no built-in ATU, pairing it with an antenna that’s resonant on two of its four bands (40 and 20 meters) meant I wouldn’t need anything to match impedance. If I decided to hit 30 meters, I would have reached into my pack and attached the Elecraft T1 external ATU which would have easily found a match. I doubted this would be necessary and I was correct about that.

By the time I finished setting up, the school buses rolled out of the park. I actually enjoyed hearing so much activity at Tuttle–what a brilliant resource for local schools.


Set up was quick and easy!

On the air

These days, I’m trying to always fit in a bit of the higher bands, so I started this activation by calling CQ on 20 meters where I worked four stations in about 4 minutes: N0VRP, KE1AK, K5PE, and K1RDD.

My activations are always pretty short, so if I call CQ POTA a few times without a reply, I’ll often use it as an opportunity to QSY.

Shortly after moving to 40 meters, I started logging chasers–40M was much more active that day. Within 15 minutes, I logged 14 stations: K3ES, KZ4KX, N8PEM, K8RAT, W8WX, WB1LLY, KZ3L, WX8J, N4CLY, KA2F, N8RVE, K2KS, and KE8PX.

It was brilliant working so many familiar callsigns during this maiden MTR-4B activation! Many thanks to all of the hunters out there!


Here’s what 5 watts into a 40 meter EFHW yielded during this short activation:

Activation video

Here’s my real-time, real-life activation video. This being the inaugural outing with the MTR-4B, I spent a bit of time at the beginning of the video talking about my initial impressions of this wee radio wonder:

Click here to view on YouTube.

MTR-4B initial impressions?

Oh yeah, I love this little radio!

Frankly, I knew I would. Steve and LnR have been making incremental upgrades to the Mountain Topper series radios for years now. They’re solid performers and optimized for low-impact QRP fun.

Get this: the MTR-4B uses only 27 ma of current in receive! I think I could do a multi-day, multi-summit activation expedition on one charge of my 3aH LiFePo4 battery. It’s mind-blowingly efficient.

To my ear, the MTR-4B sounds indistinguishable from my MTR-3B. That’s high praise in this QRPer’s world.

I look forward to taking the MTR-4B out many more activations and then sending it on to its proud owner.

If you’ve been thinking about purchasing the MTR-4B, I say go ahead and bit the bullet. As with a number of other US-based manufacturers, there’s a decent lead time, but I think it’s worth the wait.

Thank you

As I said at the beginning of this post, I feel so fortunate and humbled to be the recipient of others’ generosity. I’m so thankful to have this MTR-4B on loan for a proper vetting and review.

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 which allows me to open up my work life to write more field reports and film more activation videos. Simple as they are, it takes hours of dedicated time to publish each one.

Here’s wishing everyone an amazing week!

To those of you who are in the process of learning CW? You’ve got this. Keep up the listening practice by doing a little every day. You’ll soon be on the air enjoying this wonderful mode.

Let’s go play radio!

Cheers & 72,

Thomas (K4SWL)

12 thoughts on “My first POTA activation with the Mountain Topper MTR-4B V2”

  1. Please describe how you generate your contact map. Great and well done report. Thanks

    Pete WK8S

    1. Hi, Pete,

      I simply use It’s a great resource and makes it super easy to create a map. Simply upload your ADIF file and choose the style of map!


  2. That’s fantastic! Our ham community is the greatest. Enjoy your time with it.

    I have had mine for several months now and carry it with me in my gear every day. It is my first LNR radio and surely not my last. Ive been on the lookout for a MTR3B but find I just miss out on the sale by seconds as they tend to go fast!

    I have used it to activate parks and connected at home also. It is reminiscent of the old CW keyer kits offered by Kenga where you had to listen for the correct character to tell which menu item you wanted. The combination of this, the N0SA SOTApaddles along with a multi band EFHW or Linked Dipole make a fantastically small and lightweight kit.

    I have been testing battery life and various antennas in preparation for a late June wilderness backpacking trip to North Manitou Island off the NW coast of Michigan. Me and several other friends (one is a ham) along with my 12yr old son are going to spend three nights on the island and I’ve set aside plenty of time for a POTA/SOTA activations while there. My MTR4B kit is what I’m taking so I have been trying to use it as much as possible.

    Nice quick review and I look forward to your thoughts as you go along.

    1. Wow! Your wilderness backpacking trip sounds amazing! The MTR-4B should serve you very well indeed.

      I would love it if you take a few photos along the way and maybe write up a little report of trip to share with us! (Hint, hint!)


  3. Nice blog today, thank you. I’ve been interested in the Mountain Topper though it will have to wait. I haven’t been out lately, but hope to change things this week. Been too busy at Church, all kinda calm down now.

    Again thanks.

    Fr Richard

  4. Thanks for another great writeup. I did a first mountain top activation (albeit a small one), with my MTR 4B V2 the weekend before last and it performed very well. Both the MTR and the TR-35 have quickly become my mountain favorites, allowing me to have a sub 3lb radio kit for SOTA (I can get it down to pretty close to 2lbs if needed). It is amazing the performance that you get with these radios, for so little weight and space.

  5. Thomas
    Thanks for another great video! Mountain Topper is probably going on my wish list.
    Could you talk a bit about the computer you are using on site? In fact, a discussion about what your experience with portables for activations or in the shack would be great. Also, what programs you use on the computer for logging?

  6. The following is printed on a wall wart would it be safe to use to power the MTR 4 while in the shack?
    MODEL: IVP1200-2500
    INPUT: 100-240VAC 50/60Mz O.8A
    OUTPUT: 12.0V === 2.5A

  7. Hello Thomas,
    Great review I have recently acquired one and look forward to using it in the field. In the meantime would a wall plug that had the following printed on it be safe to use with it while in the shack?
    MODEL: IVP1200-2500
    INPUT: 100-240VAC 50/60Mz O.8A
    OUTPUT: 12.0V === 2.5A

  8. Thank you for all the amazing videos and field reports.

    I am awaiting my Mtr4b and am trying to decide what battery to get. LNR Precision’s website indicates that using the Bioenno 12V batteries requires a voltage drop. Did you use a voltage drop with the battery you used for this, did you use a partially discharged battery, or did you find that the Mtr4b could handle a fully charged Bioenno Mtr4b?

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