Build a Zero-Solder Solar Repeater
This guide walks you through building a fully waterproof, zero-soldering solar repeater using the RAK WisBlock 4631. Perfect for extending range across the Berkshires without any soldering experience required.
Time Required: Approx 60 minutes
Prerequisites: RAK WisBlock 4631, 6000mAh LiPo battery, USB-C solar panel, waterproof enclosure, mesh knowledge.
Total Cost: ~$80-120
Required Components
- RAK WisBlock 4631 — Core LoRa node
- 6000mAh LiPo Battery (JST PH2.0) — Power source
- USB-C Solar Panel (6W+) — Direct charging via USB-C port
- IPEX to Type-N Adapter + Cable — External antenna connection
- 5.8dBi Type-N Antenna — High-gain external antenna
- Waterproof Enclosure (IP65+) — With cable glands
- Waterproof Cable Gland (USB-C) — Sealed cable entry
- Pressure Relief Valve — Allows air out without letting moisture in.
- 100% Silicone Caulk — Ensures waterproofing around glands and valves.
- Polyimide Heat Tape — Useful for wrapping battery or cables inside the enclosure for safe attachment.
- Step Drill Bit — Significantly easier for drilling the plastic enclosure.
- Marine Heat-Shrink Tubing — Helps tidy cables and add thickness to cables through glands.
Optional Supplies
Instructions
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Prepare the Enclosure.
Drill three holes in your waterproof enclosure:
- Top hole: For the Type-N bulkhead antenna adapter
- Bottom holes: For the USB-C cable gland and pressure relief valve.
Install the Type-N bulkhead adapter on top and thread the cable gland and valve into the bottom holes. Seal with silicone if needed for extra protection. Leave the outer section of the cable gland disassembled until the solar panel cable is fed through.
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Connect the Antenna Feedline.
Identify the antenna connections on the RAK board. They are U.FL/IPEX connectors, which are very small, circular gold connectors with a pin in the middle. The 4631 board will have two of them, labeled as LoRa and BLE (Bluetooth Low Energy). When connecting IPEX antenna leads, make sure to have the cable end perfectly centered over top of the connector on the board, and then press straight down. Sometimes it is helpful to use a sturdy plastic tool to press down, but be sure that it doesn't slip and damage the board. These connectors are strong when pressed straight on, but can be fragile when wiggled or bent. So once these are connected, try to keep them from moving or disconnecting as much as possible.
Connect the IPEX to Type-N adapter to the LoRa terminal.
Route the Type-N bulkhead through the top hole and thread the washer and nut on from the outside. Secure tightly to prevent water ingress.
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Wire the Battery.
Plug the 6000mAh LiPo battery's JST PH2.0 connector directly into the
BATTERYport on the WisBlock 4631. Double-check polarity before connecting — reversed polarity can permanently damage the board.JST PH2.0 connectors are very common power connectors on dev boards, but they are not universal with their polarity. Luckily, they are very easy to swap. Each cable is held into the connector by a tiny plastic tab that catches on a barb on the pin. Lift this plastic tab ever so gently with a toothpick or plastic tool (to avoid the risk of shorting the positive and negative leads), and carefully pull the cable out of the connector. Make sure that the red goes to red and black goes to black. JST connectors are keyed, so they will only plug in one way.
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Route the Solar Input.
Feed the USB-C solar panel cable through the bottom cable gland. Tighten the gland to create a waterproof seal around the cable. Plug the USB-C end directly into the WisBlock 4631's USB-C port.
If the USB-C cable is too thin and the cable gland won't tighten down on it, use some 4:1 marine heat-shrink on the cable to fill the space. This will keep it water-tight and prevent the gland from wrinkling or remaining loose.
The solar panel can be mounted:
- Option A: Directly to the enclosure exterior (shorter cable, less loss)
- Option B: Nearby in a sunnier location (more flexible placement)
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Secure Components Inside.
Use double-sided foam tape, velcro, cleverly placed screws (through the RAK holes) or zip ties to secure the RAK board and battery inside the enclosure. Leave some slack in cables to avoid stress on connectors when closing the lid. Close the enclosure and ensure all seals are tight.
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External Antenna Connection.
Screw the Type-N antenna onto the external bulkhead adapter. Hand-tighten firmly but don't overtighten (The bulkhead can spin and twist/disconnect the feedline from the board). Position the antenna vertically for optimal omnidirectional coverage.
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Flash & Configure Firmware.
Connect the assembled node to your computer via USB-C and flash MeshCore firmware using the Official Flasher. Configure settings per the Recommended Settings in the Wiki:
- Preset: US/Canada 910.525MHz
- Hash Mode: 2-byte, 32 hop
- Bandwidth: 62.5kHz
- Spreading Factor: 7
Testing & Deployment
Before mounting permanently, verify everything works:
- All connections secure and waterproof
- Solar panel getting direct sunlight
- Node powered on (LED indicator visible)
- MeshCore app detects the node
- GPS lock acquired (if enabled)
For maximum range in the Berkshires, mount at elevation (rooftops, trees, mountaintops), face the solar panel south for all-day charging, and keep metal objects away from the antenna to reduce interference and noise floor.
Troubleshooting
Node won't power on?
Check battery connection polarity. Ensure the battery isn't depleted — connect to USB-C power charger temporarily to wake the protection circuit.
Solar not charging?
Verify the USB-C cable is fully seated in the WisBlock 4631. Check that the cable gland isn't pulling on the cable when tightened.
Weak signal despite high placement?
Ensure the Type-N antenna is fully connected. Check that the IPEX connector inside is fully seated. Check the MeshCore app for noise floor (how much nearby radio frequency activity is impacting the signal) and SNR (Signal-to-Noise Ratio) statistics.
Enclosure condensation?
Add a waterproof breather valve to equalize pressure. Include silica gel packets inside to absorb moisture.