New SOTA Station Design: Mountain Topper Go Box and TinySOTA

Dear all:

Now that the summer activation time is mostly over and the skitouring has not yet started, I took the time to continue working on my SOTA station. The newest project is a “MTR-5B GoBox” which has everything I need included in a sturdy case.

The project is still pending, because I am waiting for a few components, but here is already an outlook of its features:

  1. Based on the MTR-5B, so 40, 30, 20, 17, and 15 m.
  2. DC-DC Boost converter with input and output filters for 6 - 9 - 12 V from 4 AA NiMH cells (internal)
  3. TinySWR indicator
  4. Control monitor and Zero Beat Indicator based on the LMC567 IC.
  5. Volume control
  6. Rotary Encoder for VFO
  7. Battery monitor with two LEDs
  8. Palm Pico Single mounted on top with magnets from the rear (allows two different angles).
  9. Lightweight LED lamp with constant current circuit that can be plugged into the charging connector, so you have a handy little light for logging.

This time, I had the front panel made by Schaeffer; not cheap, but very satisfying in terms of look and feel.

As usual, I will put all files an instructions on GitHub.

73 de Martin, DK3IT


Very nice. Love how professional it looks.


This is fantastic. I am hoping to use just this kind of case setup to house my ubitx radio. Would you mind giving me some details about the construction? I could ask questions, but I think they’d be more easily answered if you had a photo of the interior of the radio.

Many thanks!


Dear Joe:
Apologies for the late reply!

The basic construction principle is as follows:

a) I use 3D-printed stand-offs that exactly match the inner geometry of the Peli cases. They contain a M3 thread, which I manually cut into the printed parts (cutting threads into PLA material works pretty well).

b) The panel is made by Schaeffer AG Ihr Experte für Frontplatten und Gehäuse. Since their service is not exactly cheap, I start with 3D-printed prototypes until everything works and looks as needed. You can design the front-panels with the free tool that Schaeffer provides:

However, what I do is export the cutouts from the 3D design and import them into their tool. I only use their tool for fine-tuning, like the countersinks.

The text and drawings are created in a graphics program and imported as an image into the Schaeffer tool. This is less work than using engravings, gives you more freedom in terms of design, and is multi-color.

All the materials will eventually be put up on GitHub, but I will need some time to finalize this.

Main Project and 3D-printable parts: GitHub - mfhepp/gobox: Mechanical parts and assembly instructions for turning the Mountain Topper MTR-3B or MTR-5B into a compact all-in-one station for SOTA or other ham radio operations in the outdoors.
DC-DC Boost Converter: GitHub - mfhepp/gobox-power: A 6-9-12V DC-DC boost converter for QRP rigs from 4 NiMH cells (or 2S LiPo with minor mods), e.g. Mountain Topper MTR-3B and MTR-5B.
TinySWR Indicator: GitHub - mfhepp/tinyswr: A tiny SWR and RF power indicator for QRP transceivers
Audio Amplifier and Zero Beat Indicators: GitHub - mfhepp/gobox-audio: A small PCB with a LM386-based audio amplifier for a control monitor, and a zero-beat indicator for QRP rigs, like the Mountain Topper MTR-3B and MTR-5B. (currently a mere stub)

For your own project, you will likely only need

a) the stand-offs from gobox/standoffs at master · mfhepp/gobox · GitHub
b) the front-panel from gobox/frontpanel at master · mfhepp/gobox · GitHub

Hope that helps!

73 de Martin, DK3IT


Here are a few pictures:



Oh, I have one more :wink:

Now that the MTR-5B box is completed, I had the courage to take a apart my MTR-3B-based predecessor and complete the smaller version, which I call “TinySOTA” (will also be on GitHub).

It is a Mountain Topper 3-Bander PCB plus

The total weight is 315 g including battery, charger, paddle and earphone. The box is watertight and should allow for 2 - 3 hrs of SOTA activity.

Attached, please find a few pictures. The front panel will eventually also be made in aluminium.

This one is a much trickier project than the MTR5B GoBox, because you have to do quite a few mods on the MTR PCB. For instance, reusing the power switch requires unsoldering the Q5 transistor which serves as a polarity protection. Also, space is so tight that I had to shorten the wires of the four push-button switches, etc.

73 de Martin, DK3IT


This is exceptionally helpful Martin, so thank you! As it turns out, I have had zero time to work on the ubitx over the holidays so, I’ll be using this information for sure.

Again, many thanks!

73 de Joe KD9JLV (or possible N0MAP. I’ll know when the FCC database starts functioning again)

Nice Work, Martin!

Ken, K6HPX

Martin, very interesting and successful concept!
Really fantastic work!
I use a similar “box” for backpacking:

Based on the “Piligrim SMD/PRO” project. (DCR)
Many thanks!


Here is a better photo of the actual construction. The batteries I use are these:

Much cheaper iPhone 2G batteries like these;ARTICLE=90647;SEARCH=akku%202g

might also work, but I wanted to use a brand product with a complete datasheet. Also, the wires on iPhone battery replacements might be too thin for the ca. 1.5 A peak currents.


PS: An essential aid was SOTAbeams’ “liquid electrical tape”: Buy Performix Liquid Electrical Tape Black Online | Amateur Radio Accessories and Equipment.


Today, the CNC-milled and color-printed front panel for the TinySOTA station arrived from Schaeffer AG. I can’t wait to put it into place :wink:

73 de Martin, DK3IT


That looks terrific, you should have a big smile when it all goes in!

Nice work

Thanks for all your kind feedback!

Today, I managed to mount everything on the new front panel. The total station weight is now 329 g including the MTR-3B, TinySWR indicator, 2S 1000 mAh Lipo battery, DC-DC- boost converter for 9 and 12 V, Palm Pico Single, retractable earphones, volume control, and balanced charger that can be powered by a simple MicroUSB port; all in a watertight and extremely robust enclosure.

Attached, please find a few snapshots of the final result.

73 de Martin, DK3IT

PS: The red and green LED are misplaced; will fix that asap.


Perfect hit, Martin!

That is an enviable radio!

Thanks for all of your nice feedback!

As promised, I will put instructions and files for 3D printing and front panel on a Github repository, but it will take a few weeks or so.

73 de Martin, DK3IT

This is just AMAZING. I might have to do this with my MTR someday. Very nicely done!

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Complimenti! Surely if you went with plastic screws you can get it down below 325g

German craftsmanship at it’s best

John ve3ips

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Beautiful Martin.
Keep up the good work :slight_smile: