TPU Linked EFHW Antenna Wire Link

Currently Untested. Will update once I print a few of these out and build an antenna with it. If you're ambitious and want to try it out yourself, please let me know how it goes.

This is a highly durable wire link designed specifically for QRP and portable End-Fed Half-Wave (EFHW) or Linked Dipole antennas. Optimized for field operations (POTA/SOTA), this design features a 3-hole strain relief system that completely isolates mechanical wire tension away from your electrical connections.

This hardware offers a 100% toolless field experience that won't strip, spin, or fail in extreme environments.

Two variants are supported by adjusting the outer hole diameters: 24 AWG silicone wire and 26 AWG silicone wire.

Features

• Toolless Field Operation: Change bands or isolate antenna links instantly using standard M3 wingnuts—no screwdrivers required in the cold or rain.

• Streamlined & Snag-Free: Generous fillets and fully rounded edges ensure the link glides smoothly through tree branches during deployment and pack-up.

• Captive Hardware: The bottom of the link features a precise hexagonal recess that locks the M3 bolt head in place, preventing it from spinning while you tighten the wingnut.

• Anti-Twist Ring Terminal Pocket: A shallow 0.5mm recess on the top face locks the ring terminal in place, preventing your electrical wire from twisting or shearing.

Required Hardware (Per Link)

• 1x M3 x 10mm (or 12mm) Stainless Steel Hex Head Machine Bolt

• 1x M3 Stainless Steel Wingnut

• 1x M3 Stainless Steel Flat Washer (placed under the wingnut to protect the ring terminals)

• 2x M3 Soldered or Crimped Ring Terminals (for the incoming and outgoing antenna wire elements)

Recommended Print Settings

For maximum durability under load, this part must be printed flat on the build plate. Printing flat ensures the filament strands run the entire length of the link, meaning the wire tension pulls along the grain rather than pulling the layers apart.

• Material: Hard TPU (95A or 98A) or Nylon. (PLA or PETG are not recommended, as they can crack or snap when snapping against tree branches under tension).

• Perimeters/Walls: 4 to 6 walls. (With a 0.4mm nozzle, this will make the center core 100% solid plastic to prevent squishing under clamp load).

• Infill: 100% (or 50%+ Gyroid).

• Layer Height: 0.2mm.

• Supports: None required. The captive hex pocket on the bottom is small enough to clear via standard bridging.

• Cooling: 100% fan speed after the first layer to ensure the overhang fillets print perfectly smooth without stringing.

Wire Fitting Guide

• 24 AWG Variant: Uses 2.0mm holes with a 3.5mm pitch to accommodate standard 1.6mm OD silicone insulated wire.

• 26 AWG Variant: Uses 1.8mm holes with a 3.2mm pitch to accommodate standard 1.4mm OD silicone insulated wire.

• Tip: Weave the wire through the three strain relief holes first, leaving a slack tail to solder onto the M3 ring terminal.