Building a Solid MeshCore Node

 

Practical hardware and enclosure notes

1. The Enclosure

Material

A polycarbonate enclosure is a great default choice. It's strong, weather-resistant, and widely available. Since many boards also carry a Wi-Fi radio, a plastic enclosure lets that signal pass through without the shielding problems a metal box would introduce. A clear or semi-clear lid is a nice bonus, since it lets you glance inside and debug or check LEDs without opening anything up.

Example: Hammond 1554UPL, with inner-panel

Don't chase full waterproofing

Making an enclosure genuinely watertight is hard, and — more importantly — you have no practical way to verify that your design actually achieves it. Rather than chasing a seal you can't test, aim for something simpler and more robust:

• Keep the enclosure closed so that direct rain can't get in.

• Where cables enter at the bottom, make the openings slightly larger than they need to be. If any moisture ever does find its way in, it can drain back out through the same gap instead of pooling.

If insects or spiders become a real nuisance inside the box, a bit of mosquito net fitted on the outside of the enclosure (around the cable entries, not inside) can help — but only reach for this if it's an actual problem you're experiencing, not as a precaution.

2. The Backplane and PCB

Inside the box, build on an aluminium backplate. It doesn't rust, it's easy to mount things to, and it gives the whole build a clean, professional look and feel.

A small custom PCB

A simple custom PCB mounted to that backplate makes a big difference to maintainability. Put the radio module on a pin header rather than soldering it directly — that way it can be swapped out later without any rework.

Power supply: skip the switching regulator

It's tempting to reach for a switch-mode power supply (SMPS) to save a bit of power. In this application, that trade-off usually isn't worth it. SMPS designs generate wideband RF noise that raises the noise floor right where your radio is trying to listen — and just as seriously, they produce conducted and radiated spurious emissions that are genuinely difficult to predict or fully suppress at the design stage. This is not a minor caveat: those emissions can desensitize your own receiver, and depending on layout, grounding, and shielding, can also couple onto the antenna cable or the DC wiring and radiate from there, affecting other nearby equipment as well. Properly verifying that an SMPS design is truly "clean" requires access to an EMC lab, with testing across the full range of expected temperatures, input voltages, and RF loading conditions — a lot to ask for a hobby project. Put plainly, an unverified SMPS design is a gamble with your radio's performance, and potentially with your neighbors' reception too.

A simple, old-fashioned linear regulator (something in the LM7805 family) sidesteps all of this. These parts have been around for decades, are thoroughly proven, and simply don't generate RF noise the way a switcher does. Pair the regulator with proper bypass capacitors on the PCB and you have a clean, quiet, easily-trusted power supply.

And more generally, avoid putting any charging electronics or switching circuitry up at the mast itself — that's right next to your antenna and coax, and switching noise there can radiate straight out through them. This doesn't just hurt your own node's reception; on a site with a good, clear view, it can end up interfering with other people's equipment too.

A helpful side effect: heat

A linear regulator dissipates more energy as heat than a switcher would — and inside an outdoor enclosure, that's actually useful. Somewhere in the range of 1–3 W of dissipation helps keep the inside of the box a little warmer than the outside air, which keeps you further from the dew point (the temperature at which condensation starts to form on internal surfaces). Mounting the regulator's package to the aluminium backplate lets that heat spread out and dissipate efficiently, rather than creating a hot spot.

3. RF Filtering

If you need a filter, use a cavity filter — steer clear of other filter types for this purpose. A cavity filter is really only necessary when your node sits close to a GSM mast, and "close" here means line-of-sight close: if you can see the mast with your own eyes from the node's location, it's worth considering. These filters run around €100, so it's best treated as a targeted fix rather than something to add by default.

4. Antenna Placement and Cabling

At 868 MHz, coax cable is both expensive and a real source of loss if you're not careful. From a system-design perspective, it's much better to mount the node itself right at (or as close as practical to) the antenna, rather than running a long coax feed. This saves money and avoids the losses that add up quickly at this frequency.

5. Power Cabling to the Node

A standard 12 V cable works fine from the node, but make sure it's rated for UV exposure so it doesn't go brittle outdoors over time. It's also a good idea to route this cable through a ferrite core in the enclosure. This does double duty: it acts as a common-mode filter, and it also functions as a strain relief, so an accidental tug on the cable outside doesn't pull the cable loose from the PCB inside.

At the power supply end, use the Fair-Rite P/N 0431177081 core a solid choice here, and one that works especially well in HF-heavy environments (such as near ham shacks). The table below shows how impedance and attenuation scale with the number of turns through the core, which can help you pick a turn count that fits your situation:

Highlighted cells mark the stronger-performing turn counts at each frequency — more turns generally buys more impedance and attenuation.

6. Battery Backup and Charging

Most nodes benefit from a battery backup, and there's no need to overthink the starting point:

• A regular car (lead-acid) battery is cheap, easy to charge, and tolerates cold environments well. Pair it with a simple linear trickle charger running off the grid.

• If you'd like to upgrade, a LiFePO4 battery (SOK for example) is a great step up. These are easy to charge, hold a large amount of energy, and are reasonably priced, giving the node a long runtime on battery alone.

• For charging from the grid or from solar, Victron Energy chargers are a reliable, high-quality option.

One important placement note: batteries dislike temperature extremes, so it's better to keep them indoors rather than mounting them high up on a mast.

Layout is such that the USB port is still accessable.