u/MeshDaddySD

Proof of concept for anyone building a mountaintop Meshtastic node.

My first attempt failed.

I used an aluminum IP67 enclosure, but I made penetrations into the box without accounting for pressure equalization. With hot/cold thermal cycling and some rain, the pressure changes slowly drew moisture into the enclosure. Condensation formed when the sun heated the box and eventually killed the RAK board.

So… second attempt.

This new build survived: • Simulated hurricane rain • Hot/cold thermal cycling • Direct sun exposure • Outdoor overnight humidity testing

Environment: • 1550 ft elevation • High RF site with 100+ radios • Cellular, TV, microwave backhaul links (~22 GHz nearby) • Temperatures from ~50°F to 95°F • Direct sunlight year round

Build details:

1. Enclosure Grounded aluminum enclosure used to help shield the radio from excessive RF spillover in a very noisy RF environment.

• Metal bulkhead antenna connector • Metal solar power input connector

2. Pressure Equalization Vent Added a waterproof membrane pressure vent specifically designed for enclosure equalization. This was probably the single most important improvement.

3. Cable Management Very short antenna coax to reduce loss.

Added a drip loop so any water intrusion from a seal failure drips away from the electronics instead of onto the board.

4. Condensation Protection The LoRa board is coated with electronics safe silicone conformal protection.

Purpose: If the vent, seals, and silica pack ever all fail simultaneously, condensation is less likely to short the board.

5. Dual Battery Design • External solar battery: 5200 mAh • Internal backup battery: ~10,000 mAh

The internal battery is reserved as emergency backup only.

If the solar system fails or is vandalized, the node remains online long enough for me to remotely identify the failure condition.

6. Physical Security • U-bolt mounted directly to pole • Mounting hardware inside enclosure • Stainless tamper resistant screws • Mounted ~12 feet high

It’s also a 4 mile hike to reach the site, so casual theft risk is pretty low.

7. Labeling Labeled as a community network device with: • Operating frequency • FCC Part 15 compliance notice • Contact number

8. Solar • 5 watt solar panel • 5V DC output • USB-C powered

9. Radio Hardware RAK4631 / RAK4632 based system

10. Antennas • 2.4 GHz antenna for Bluetooth • 5.8 dBi omni directional 915 MHz antenna

Total cost: Approximately $225

Biggest lesson learned: An IP67 box alone is NOT enough for outdoor thermal cycling. Pressure equalization and condensation management matter just as much as waterproofing.

If people want the exact parts list and Amazon links here you go! ; https://amzn.to/4fhT3HO

Feel free to ask any questions!

PS. My third potential router location (Palomar Mountain, is a snow capped summit at nearly 6000 feet in the winter. With think Ice build up.) ❄️ I need advice from people who live in cold places!!

Sharing for others who may someday build a mountain top router.

Deployed the Mountain top node, only to have discovered after a not typical rain storm in SoCal, that the modifications to the NEMA 67 metal box compromised the weather proofing.

I learned that rain can track through the threads of a bolt and bypass rubber sealing gaskets.

Also, that when you use a “sealed box” any moisture in the box, will condensate when the box heats and cools.

You can see this in the attached photos. The condensation killed the RAK board as you can see in the picture. (Yes I tried cleaning the board to no avail).

Next steps:

1.Double rubber gaskets on U bolt hole entrances on the back of the box with thread sealer.

2. Silica moister absorbing pack inside.

3. Breathing vent specific designed to not let moisture flow in.

4. Full direct prolonged water test.

We’ll get there San Diego.