Hardware
Parts
The small things that decide whether a node works well or barely works at all.
SMA and RP-SMA are not the same
They look nearly identical and they are not compatible. Check which one your board has before ordering an antenna. Most Meshtastic hardware uses SMA; the LILYGO T3 S3 uses RP-SMA.
Antennas
The antenna matters more than the radio. A cheap board with a decent antenna outside beats an expensive one with a stub antenna indoors, every time.
The Gizont 868 MHz is cheap, widely used locally and good enough for most fixed nodes. Whatever you buy, make sure it is cut for 868 MHz — a 433 MHz or 915 MHz antenna will work badly and can damage the radio.
Never transmit without an antenna
Powering up a LoRa board with nothing attached can destroy the transmitter. Connect the antenna before you connect power.
Adapters
Boards that only expose a u.fl connector need a pigtail to take a normal antenna. Check the SMA gender and polarity at the antenna end before ordering.
The u.fl connector itself is fragile and rated for very few mating cycles. Fit the pigtail once and leave it alone.
Putting a node outside
Anything mounted outdoors in Pirkanmaa needs to survive from about −30 °C to +30 °C, plus driven rain and ice. A sealed enclosure with a downward-facing cable gland, and silicone tape over the antenna connector, covers most of it.
Lithium cells do not charge below freezing. If the node is outside over winter, either keep the battery indoors or use a charger that stops when cold.