Getting my hardware sorted

Before I plugged anything in or installed a single package, I wanted to make sure I had everything I needed on the bench and that I understood the legal framework I’m operating within. Running LoRa in the EU isn’t complicated, but there are real limits I need to respect — and getting them wrong doesn’t just risk a fine, it directly affects whether my mesh actually works well in practice.

Here’s what I’m working with:

Item	Notes
2× Heltec WiFi LoRa 32 V4 boards	Confirm they’re the standard V4, not the Expansion Kit or Touch variant — those are different flash targets
2× antennas (868MHz!)	Must match the actual frequency I’m using. A 915MHz US antenna won’t perform correctly here
2× USB-C cables	Must be data-capable, not charge-only cables. This trips people up constantly — cheap cables often carry power only and the Pi simply won’t see the device
Raspberry Pi 3	With its usual PSU, SD card, and case. You could use a newer model.
(Later) Pi Zero 2 W + power supply	For the remote node compute — not needed yet, just on order

The antenna rule I’m treating as non-negotiable

The very first thing I learned about these boards: always attach the antenna before powering on. Transmitting into an open port with no antenna can destroy the SX1262 RF frontend almost instantly — it’s not a maybe, it’s a when. So my rule is simple: antenna on, every single time, before any USB plug-in or power-up. I’m making this a reflex now so it never becomes a mistake later.

EU 868MHz — what I actually need to know

This is where it gets interesting from a regulatory standpoint, and as someone interested in RF I actually wanted to understand this properly rather than just copy settings from a tutorial. The 863–870MHz band we’re operating in isn’t technically an ISM band in the ITU sense — it’s a Short Range Device (SRD) band, governed by EC regulation with ETSI EN 300 220 as the harmonised technical standard. Two limits matter for my build:

Transmit power: carrier power is capped at ≤25mW ERP on the relevant sub-bands. The Heltec V4 is technically capable of much higher output at the chip level — I must not run it at full power on a licence-free EU channel. 25mW ERP works out to roughly 14dBm, which becomes my target TX power setting when I get to Chapter 6.

Duty cycle: the band is divided into sub-bands with different duty cycle limits. The two I care about are:

Sub-band	Frequency range	Duty cycle	My take
M	868.0–868.6MHz	1%	Home to the three standard channels (868.1, 868.3, 868.5MHz) — heavily used, only 36 seconds of TX per rolling hour
P	869.4–869.65MHz	10%	Less crowded, 6 minutes of TX per rolling hour — much more breathing room for a mesh

I’ve decided to run on 869.525MHz (P sub-band) for exactly this reason. The 10% duty cycle gives my mesh room to actually function — periodic announces, message traffic, and the occasional file transfer — without constantly bumping into the legal ceiling. On a 1% channel, a busy mesh starts throttling itself into near-uselessness surprisingly quickly.

Why this isn’t just a legal checkbox

This is the part I find genuinely important to understand: getting the duty cycle configuration wrong isn’t just a regulatory problem, it’s a practical one. RNode firmware enforces duty cycle limits in software once I tell it the correct region and parameters. If I configure things incorrectly — say, too aggressive an announce interval on a 1% channel — the firmware will throttle my own transmissions and the mesh will feel sluggish or drop packets entirely. Setting this right in Chapter 6 directly determines whether my network performs well, not just whether it’s legal.

One thing worth noting: some EU member states have national variations on top of the ETSI baseline. Since I’m in Germany, the Bundesnetzagentur is the relevant authority — but for the power and duty cycle limits above, the ETSI EN 300 220 baseline keeps me safe and compliant. Worth a quick check against your own national regulator if you’re following along from elsewhere in the EU.

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Hardware is on the bench, antenna rule is locked in, and I understand the regulatory framework I’m operating within. In Chapter 3, I’ll start getting the Raspberry Pi 3 ready — OS, Python, and installing the Reticulum tools I’ll need before anything gets plugged in.