kv4p HT

Turn your Android phone into a modern ham radio transceiver

Open source hardware & software for makers and tinkerers, 1 watt VHF or UHF

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Radio for the modern maker

kv4p HT is a homebrew 1 watt radio available in VHF or UHF that plugs into your Android phone's USB-C port, transforming it into a fully-featured handheld transceiver. Completely off-grid. Completely open source.

Note: kv4p HT is an open source project you build yourself. It has absolutely no warranty, or guarantees on functionality or reliability! Requires at least a Technician class amateur radio license to use. That said, have fun. :)

Why kv4p HT?

Designed for hams who code, makers who solder, and anyone who wants a radio they can truly own.

Inexpensive Build

Just a few components to solder, buy the parts yourself or get a kit.

Android Powered

Leverages your phone's screen, GPS, and battery. No separate charging needed.

Full-Featured APRS

Built-in 1200 baud modem for SMS-like text messaging plus position beaconing, unlike most radios that only offer beaconing.

Fully Open Source

GPL3 licensed: Android app, ESP32 firmware, PCB designs, and 3D printer files.

No Internal Battery

Sips power from your phone. Perfect for go-bags or glove compartments.

Accessible Design

Live closed captions, sticky PTT with haptic feedback, and animation controls.

Build Your Own

From parts to on-air in six steps. No deep experience required, just basic soldering skills.

Watch the complete build walkthrough on YouTube

1

Get the Parts

Order a convenient kit with everything you need, or source components yourself.

Halibut Electronics

Chelegance

Building from scratch?

Custom PCB from GitHub designs v2.0e (order from PCBWay/JLCPCB)
SA818-V or SA818-U radio module (or DRA818V/U can be used)
SMA male antenna of your choice, such as pocket-size or 1/4 wave Signal Stick
U-shaped USB-C adapter (AliExpress, select "C female-C-C")
Sticky gel pads to mount to your phone

2

Solder the Board

Solder the radio module and any through-hole components to your PCB
Trim the SMA connector legs flush so they won't contact your phone
If you bought a kit, this may already be done for you

3

Print the Case

Find a case matching your PCB version (1.x or 2.x) on Thingiverse
Pro tip: Use 2-color printing for a professional look (learn how)

4

Assemble

Snap the PCB into the 3D printed case
Cut a thin strip from the sticky gel pad to attach kv4p HT to your phone
Screw on the antenna

5

Flash Firmware and NVS

If you bought a kit, the vendor likely already did this step. Otherwise, you'll need to flash the ESP32:

Open Firmware Flasher

6

Install the App

Requires Android 8+ (2017 or newer).

Get it on Google Play

QR code for kv4p HT app