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1.Product Description:What is it?
Thank you KV4P for his great contribution to this project.Turn your Android phone into a modern ham radio transceiver.
kv4p HT is a homebrew VHF radio that makes your phone capable of voice and text communication completely off-grid with at least a Technician class amateur radio license.
The radio simply plugs into the USB C port on your Android smartphone and transforms it into a fully-fledged handheld radio transceiver. It's completely open source (GPL3): the Android app, ESP32 firmware, PCB designs, and 3D printer files.
It's small enough to fit in your pocket and take anywhere, and since it has no internal battery it's the perfect radio to put in a go-bag or your car's glove compartment.
2.Features:
-100% ham radio, always completely off-grid
-Crystal-clear 44kHz 8-bit ADC/DAC audio, with filters and squelch
-Texting with notifications just like SMS — radio-based APRS messaging (not just location) with built-in 1200 baud modem
-Scan through unlimited memories and groups
-No battery means nothing to charge except your phone
-1 watt transmit can go miles yet sips your phone's battery
-Accessibility options: live closed captions (on supported phones), turn off animations, sticky PTT with haptic feedback
3.Firmware Version:
Android app update v1.73, ESP32 firmware v5
-Add new mic gain option to settings
-Add new settings to control rx and tx sampling rates
-Add setting to change bandwidth, narrow or wide
4.Test results:
KV4P:tested harmonic filtering with a TinySA spectrum analyzer to ensure it meets FCC part 97 spurious emissions requirements (which for VHF must be at least -40dBc for 2nd harmonic and below 10uW).
5.Package list(Assembled with case):
- kv4p HT Module*1
- ESP32 Module*1
- Short Micro USB to USB C Cable*1
- Adapter Micro USB to USB C*1
- SMA Female*1
-Dual Band VHF UHF 136-174MHz 400-470MHz Ham Radio Antenna*1
-3D Print Case(PETG-CF)*1
Omayka Gutierrez
Reviewed in the United States on May 9, 2025
Excelente me funciono muy bien
JW
Reviewed in the United States on March 27, 2025
The KV4P is a very interesting toy if it works for you. It is a project device that is like a beta release video game that is not ready for the masses. I have bought this device two separate times now and have tried each one with 3 separate android devices and it has never, not once been able to actually pick up any signals. The KV4P will connect to the device after much frustration and multiple firmware flashes via their website. It will transmit (it seems), but it cannot hear at all!. I even hooked this up to a VHF UHF antenna 30 feet up and it couldn't pick up a single signal. Not a single one! For the price they charge you can get 2 or 3 cheap Chinese radios that have exceptionally far better performance. I've been a ham for a very long time and am very tech savvy with the hobby as well as Android. Unfortunately, this is a hard pass. The included instructions are absolutely atrocious and they leave it to you to actually figure out how to get it up and running. If you want support, you have to join their discord group (like most beta devices) and try to get help that way. I will be returning both of these KV4P's and will put that money towards something else. I hate to sound harsh to a startup as I always want to encourage the ham radio hobby. But this needs a ton of work (likely on the firmware end) and shouldn't be sold as a finished product. (Additionally, one of the included USB cables was bad leading to a lot more headache). I have spent way too many hours on what is advertised as plug and play.
Customer
Reviewed in the United States on April 10, 2025
Hey, no kidding here...I have NO idea why anyone would have problems with this KV4P Radio Module for Android. I read the ONE review for this and for the money - geez, $40 - I took the gamble and I think I hit the jackpot! All I had to do is reload the KV4P Radio Module firmware with the latest version using the supplied CLEAR INSTRUCTIONS FROM THE BOX and within 10 minutes I was receiving local repeaters here in Pittsburgh (actually Washington and I'm located in Canonsburg). Shortly after that I put all the repeater splits in, tones, and within 15 minutes of unboxing this i had it fully running on voice receive and transmit, operating normally through the local repeaters. What's more, I discovered this isn't just a VHF radio module - IT CAN DO UHF REPEATERS TOO!! So I loaded those and they work great too! BONUS!! Now I did discover that the supplied USB cable is cheap and can give you fits in transmit because the RF in transmit is interfering with that cable. No big deal - I ordered a short shielded cable and a snap on ferrite bead from Amazon that set me back a whopping $20 (come on, it's pocket change) so it'll be bullet proof. The developer of this radio module is on Discord and I spoke to him directly about some if my observations and he was VERY RESPONSIVE AND HELPFUL. So they didn't just make this thing and run away - THEY'RE CONSTANTLY IMPROVING IT. Final thoughts: I'M SUPER HAPPY WITH IT AND THIS WORKS GREAT ON VHF AND UHF. BUY ONE!!!!
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