KXUSBC2 – Unofficial Internal USB-C charger for the Elecraft KX2

Credit

All credit for this fantastic innovation goes to Manuel, HB9DQM. Manuel has made the hardware and firmware freely available under the CERN-OHL-W-2.0 license.

Introduction (by Manuel, HB9DQM)

Have you ever forgotten to bring your KX2 charger on a trip, accidentally torn the speaker wires after countless battery removals, or found yourself with a dead phone battery on a summit while the KX2 still had plenty of power? I’ve managed all three. Each time, I wished the KX2 simply had a USB-C port — no more removing the battery, no special charger to pack, and the ability to top up a phone.

External power banks are awkward when operating handheld with the AX1 and may cause QRM. The KXIBC2 option still requires a specific AC adapter, charges very slowly, and cannot supply power to a phone. Perhaps the best solution until now was to bypass the KX2's built-in reverse-power diodes and connect an external USB-C charger. But with all of these solutions, you can forget something at home that you can’t buy on the go.

I prefer fully integrated things that are simple and foolproof to use. So I set out to design an option PCB that installs in place of a KXIBC2 or KXIO2 and adds a bidirectional (dual-role) USB-C port for charging and discharging the internal battery. In homage to Elecraft’s naming convention for KX2 options, I call it the KXUSBC2 — an unofficial option.

Features

• Adds a bidirectional USB-C charging port to the KX2
• Charges the internal 3S Li-Ion battery at up to 30 W
• Dual-Role Port (DRP/OTG): Can also charge an external device (phone, GPS, HT etc.) through the same USB-C port at up to 30 W (5…15 V)
• Dual input: can charge from USB-C or DC jack
• Supports PD 3.0, QC, BC1.2
• Real-Time Clock (RTC)
• RGB status LED and config button
  
• Battery voltage monitor in KX2 menu (like KXIBC2)