Thinking of getting a Mountain Topper (MTR-3B)

I’m thinking of getting a Mountain Topper 3B while I continue to learn CW. Do I need an antenna tuner for this radio? Or just a good antenna?

Should I hold off on ordering the Mountain Topper 3B while I am still learning CW?
( I hear of a 5 bander coming?)

I also really would like to use a straight key as I am still learning and a paddle seems kind of overwhelming. I hear I would need a special plug to do so? Where can I get one?

I do not have any CW equipment at the moment. I do have a home made CW key made from a clothes pin hooked up to a raspberry pi though, so I can practice transmitting.

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The Mountain Toppers are a neat little radio although to my mind 2.5W is a bit under powered.
There is quite a bit of sunspot activity and I would lean towards a 5W CW qrp rig. I built Steve Webers KD1JV tribander which has given good results for my SOTA activations.
I use a KM2 tuner with the tribander and suspect the M Topper will need a tuner as well.
Unless your aerials are well tuned which sometimes may be a bit difficult to do at random settings up at different summits.
Have read of the 5 bander which is in the pipeline, keep in mind they are a surface mount component radio which may be a bit daunting for some home constructors. Don’t know whether the 5 bander can be bought assembled. Should be a interesting qrp radio when they do become available.
On keys if you are still in the process of learning morse suggest a simple straight key for a start.
Get to know the code, have a few on air contacts and when you feel comfortable with your cw then make the transition to a paddle.
I don’t know about the key’s plugs for the M Topper but suspect they would be the same as the Tri Bander. A 3.5 mm mono plug for a straight key and a stereo plug for the paddle.
Paddles are really a thing for fast cw like 18 wpm or more. Palm Radio in Germany make the Pico Paddle which is a small lightweight key which in some cases can be fitted to the case of your radio with adapter cradles.
The Pico’s come with a made up plug and have seen a number of SOTA activators using these keys.

73’s, Nick

Hi Casey -
You can find a construction manual for the MTR series transceivers on the AT Sprint yahoo group:

The MTR transceivers require the 50 Ohm load of a resonant antenna. An automatic antenna tuner would weigh several times the MTR and so I doubt that many use one. EFHW is often a choice.

There’s an article on learning CW in the latest W7O newsletter - check it out here:


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I would suggest that you make a good antenna.
Like Etienne said an antenna tuner would be bigger and heavier than the MTR-3
One way to overcome this is to build a dipole with traps.
The pico traps from Sotabeams are awesome for that.

The MTR’s connectors are in wide use. So, no problem.

BTW: I love the MTR-3. It’s my pocket radio station (with the trapped dipole)…

73 de Pedro, CT1DBS/CU3HF

The other option is a linked dipole (versions for various band combinations also available from SOTABeams or design and build your own using the calculator in the EXTRAS section of the Sota mapping project page). The key point is the antenna should be resonant and hence not need an ATU (or more correctly stated Antenna Coupling Unit ACU).


Just a couple two band link dipoles made and tuned to the cw frequency of choice or close too. Maybe 1 for 20/40 and the other for 15/30 or 15/17 depends on what bands you are most likely to score contacts on to qualify the summit. or as has been suggested a well know G operator makes a great assortment of SOTA antennas or can supply you the gear to home grow one or two .
Ed’s suggestion of the Extras section on SMP page is a great calculator for making link dipoles that way no tuner required or extra loss as well at qrp. Just make then up and tune them something like they may be deployed out on SOTA. As Nick said not all hilltop are nice and flat and clear but as long as you get your antenna height much the same every time and the inverted V something like at home in the yard it should do ok. Have fun and hope you learn heaps proving all the theories HI.
Ian vk5cz …

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Indeed Ed.
While it works FB I find the disadvantage of the linked dipole is the need to lower the antenna to switch bands.
The pico trap, from Sotabeams, at 5 gr each, are the “automated antenna band switch”!
5 gr is less wheight than the hardware to make a linked dipole, I guess.
And 10W max it’s more than enough for most of qrp radios, including MTR, KX’s or 817.

73 de Pedro

Agreed, but if you want convenience go for the Aerial-51 UL-404 from Spiderbeam - this is an off centre fed dipole with a balun but there’s the disadvantage of this design, the Balun adds more weight to the pack than either the links in a linked dipole or indeed the qrp traps.


I would wait for the 5-bander, and couple it with an Elecraft T1 tuner.

Barry N1EU

Since 2008 happy with my KX1.
Build in ATU and 80-, 40-, 30- and 20 m band.
Antenna W3EDP = 84 ft aerial an 17 ft counterpoise.
With the 6 AA batteries in the KX1 about 1.5 W output and that was sufficient power for a QSO last autumn from a summit in Germany to Phil VE1WT in Nova Scotia.
With an external 12 V power supply, about 3 W output. On receive 34 mA.

hny es 73 de geert pa7zee

Agreed, the KX1 with built-in tuner is a fantastic SOTA radio.

Barry N1EU

The only way to currently get either of these radios is prebuilt.
Steve has made it known that he is unlikely to do another run of the MTR5 and the 3 has already been outsourced to LNR.

The only way you’re going to get a kit is by hanging around on the ATSprint group and hope someone sells one that they are sitting on. (It happens - there was an ATS3 going quite recently).

If you are in no rush, i’d wait for LNR to start rolling out the 5, it gives 2 extra bands in virtually the same footprint and weight. It also has a nice digital display which makes chasing S2S much slicker IMHO.

Straight key is selected by closing the key contact at switch on. It uses the same plug.
I’d recommend the ubiquitous EFHW, it will outperform the dipole, is easier to deploy and and requires next to no feeder :smile:

Whichever of the ATS/MTR rigs you get, you won’t be disappointed.


Luckily the MTRs are quite capable of double that :smile:



The Mountain Toppers quite happily do 5W they just need 12.0v to do it. The quoted 2.5W is from a 9v supply.

Colin G8TMV

The tuning encoder option on the new MTR-5 is also very slick for those of us who don’t much like the up/down tuning switches. I’m curious whether the assembled MTR-5’s will support that feature or purchasers will be left to add it on their own.

Barry N1EU

Thanks for all of the suggestions everyone. I am in no rush, so I will see if a MTR 5 bander comes on the market in the next few months (hopefully assembled). I thought about going with a radio with the built in tuner (less stuff to carry is nice), however I think I like the versatility of using an antenna tuner for different radios if the need arises, rather than having to keep buying them.

Does anyone have any experience with this tuner?

If that is no good, then I will get the Elecraft T1.

Any suggestions on a light weight (not super expensive) straight key?

Thanks :slight_smile:

The MTR series of rigs are good performers. Personally, I tend use a linked dipole with 4m /12ft pole as a support. With about 2 to 3 watts out, the system works nicely in Europe. With the antenna so low, it’s easy to adjust links without lowering the antenna :smile:

A tuner and end fed would work fine, but note that the PA is not robust when it comes to reactive loads. The 3B MTR has a built in protection system I believe that slowly ramps up the power output in ‘tune’ setting, but other rigs in the series do not. The tuner Stavebnice Altoids L Tuner | would seem to be ideal for an MTR.

The MTR-5B works well, using the 5B on 15m and 17m has provided DX contacts (>2000 miles) on every outing. The display adds a great deal of convenience.

One thing about the LNR Precision MTR that seems to be widely reported is that the power o/p is often low due to the PA inductors not being properly tweaked into their sweet spot.

73, Colin M1BUU

Hi Casey,
Yes I built this tuner and have used it on a couple of activations with my end fed half wave wire antennas. It works fine (“does what it says on the box”). Not sure if it will work with any other types of antennas though - for example with an off centre fed dipole you would need to run ladder line to the antenna and then connect the other end of the ladder line onto the unit. I haven’t tried this.

I still recommend using a resonant dipole of some kind so that you don’t need an ACU, as a more efficient emitter but it will depend on your own particular requirements and the summits you go to. Having end-fed half wave antenna that you can throw one end over a tree branch, means you don’t need to take a telescopic fibreglass support pole, so you save weight. If there aren’t any trees on a summit however you’re stuck.


I use the MTR3b with a SOTA tuner. The tuner works FB as a small, light EFHW tuner. It doesn’t do other types of antennas so I you want to do some type of center fed or OCF dipole you’ll need something else to tune it with. In my humble opinion, the EFHW is among the best antennas for SOTA. It only needs one support, little to no feed line, very small and light when roled up, probably the quickest and simplest to deploy, very efficient, very versatile. It can be deployed as a sloper, inverted vee, inverted L, vertical. The vertical comonents of some of these configurations give you a lower takeoff angle than a flattop dipole giving you some extra range.

The MTR3 is a nice small radio. It’s main handicap is its display. It makes it very inconvenient to tune around and look for a QSO. This isn’t a problem for SOTA activations usually as you pick your op freq.
as for power, well I’ve only use it on 20 meters for SOTA but all my activations have given me a pile up of about 12 people before I’ve exhausted all the people who could hear me. The average range of people I’ve spoken with is the same as my 100 watt shack rig with a dipole on 20 meters but my average sig report was more around 559 on MTR as aposed to 779 on shack rig.

Hi § Personnaly, for my MTR-3B i use a [Trapped EFHW Antenna 40/30/20m QRP](http://Trapped EFHW Antenna 40/30/20m QRP) from It’s a very good device at low price. for only 30€ shipping included you have an antenna accorded to all MTR-3B Bands.