Elecraft KX3 Kneeboard

v2 Updates

Standard version

• Softer edges throughout: a 1 mm chamfer on the bottom (which also prevents elephant’s foot) and a 1 mm round-over on top. The walls beside the KX3 foot pockets stay square so the feet still lock in.

• Shock cord keyholes narrowed to 2.0 mm so 3 mm shock cord grips firmly, with a chamfered entry and a knot seat underneath.

• Chamfered strap slots and cord holes, so they’re easier on webbing and cord.

• Light bevel on the washer pocket rim.

• Cleaned-up model: one watertight solid, single color, prints flat with no supports.

Battery version (new)

• Same board, with the plate extended 62 mm behind the radio (190 x 222 mm overall). It’s the same 5 mm plate, with no walls, so it’s no taller to print.

• Two ways to hold it, use either or both:

  • Strap: one 1.5 in hook-and-loop strap through a front slit and one of three rear slits, positioned for the Anker Prime A1340 (27,650 mAh), TalentCell 12V 6Ah LiFePO4, and INIU P512 (20,000 mAh).

  • Shock cord: two cords from front holes into rear grip slits that are open to the back edge. The cord wedges in wherever the back of the pack lands, so it fits packs roughly 26 to 58 mm thick, including ones not listed here.

Summary

This is a leg-mounted kneeboard for the Elecraft KX3. The radio lays flat on the board and is held firmly by 3 mm shock cord routed across the rig and anchored through holes at the board edges. The board straps to your thigh, so you sit down, cinch it on, fire up the radio, and you are on the air. No table required.

Designed for real portable operating: POTA activations, SOTA summits where flat ground is scarce, and any grab-and-go field setup. It also works well for sitting in a car and operating. Requires grip handles to retain the shock cord, and works with or without heat sink upgrades.

How It Works

•     The KX3 sits flat on the board. Cutouts provide clearance for the radio's feet and the screw heads on the bottom of the case, so the rig seats tightly and does not shift.

•     3 mm shock cord passes through holes at the board edges and tensions across the body of the radio, pressing it down against the board.

•     The board attaches to your leg with a 1.5 in strap threaded through printed slots.

•     A 1/2 in x 2 in fender washer glues into the board to create a magnetic mount, so a key or paddle with a magnetic base snaps onto the board right next to the radio with an extra shock cord to prevent movement (optional).

Bill of Materials & Links

•     3 mm shock cord — 2 ft required. Link

•     1/2 in x 2 in fender washer — 1 required, plus super glue or adhesive of choice. Link

•     1.5 in cable strap — 3 ft required. Link

Print Settings

•     Material: PETG, PCTG, ASA, or similar. Do not use PLA — it will warp and soften in heat (hot car, direct sun).

•     Layer height: 0.20 mm

•     Walls / perimeters: 4

•     Infill: 25%

•     Supports: None needed (flat board with edge holes).

•     Board footprint: 190 x 170 x 6.5 mm — fits a standard 220 mm bed and larger.

Assembly

1.  Glue the 1/2 in x 2 in fender washer into its pocket in the board and let the adhesive cure.

2.  Thread the 1.5 in strap through the printed side slots.

3.  Route the 3 mm shock cord through the edge holes, lay the KX3 flat on the board, tension the cord across the radio, and secure. Adjust so the rig is snug but the side connectors stay accessible. I like to use a little bit of heat-shrink tubing to make the end of the cords easier to grip.

4.  Snap your magnetic-base key or paddle onto the fender washer.