Kv4p HT – A homebrew 1W radio (VHF or UHF) that plugs into an Android phone
kv4p.com97 points by krupan 3 days ago
97 points by krupan 3 days ago
Previous discussion on 14-oct-2024 https://news.ycombinator.com/item?id=41818609 191 comments
I used to use SDR for DAB radio in the nexus 7 in the dash of my BMW E46. It didn’t work very well but was closer to being some kind of radio receiver (not trans at least)
Is it so difficult to have schematics and pcb exported as PDF so that people do not need to fire up KiCAD to view the stuff?
Is it still worth it to mess around with older full duplex handhelds ?
> 1 watt transmit can go miles yet sips your phone’s battery
How far can such a device reach in a typical urban environment with the longer antenna?
VHF is effectively line-of-sight, and no antenna size can change that (although it does improve efficiency for both sending and receiving), so for two handheld radios, you are limited to about 10 km.
The only thing that really helps extend the range is elevating the antenna, and repeaters allow you to do that even between two mobile stations.
You can extend the reach using repeaters. This free app is handy for that https://hearham.com/repeaters
1w seems a little limited? A cheap baofeng is 8w.
Those cheap baofeng's are illegal to use where I live on most of the spectrum they can operate on. Illegal to press the talk button anyway.
So maybe the 1w is also a regulatory issue.
How does the FCC enforce this sort of thing? Are they listening in to certain frequencies nationally with the ability to triangulate a handheld down to actually identifying someone?
They mostly don't. They send scary letters and maybe eventually fine someone. They have a handful of triangulation vans for the entire US. The barely respond to complaints that are revenue impacting and generally don't respond to complaints from hams that a non ham is using their equipment. Once a quarter they make an example of someone so that it appears they enforce things. The people they make examples of are usually trying really hard to troll them or doing something highly disruptive and these will end up on a few websites and magazines.
People tinkering and staying away from ham bands will generally be fine and for the cheap ham gear that made easy by design usually by doing a factory reset or worst case having to clip a diode to widen their frequency ranges. Most ham gear is designed to be highly hackable.
Most of the time they get a complaint, and they investigate.
https://www.fcc.gov/reports-research/guides/fcc-enforcement-...
Wow, you mail them the complaint? No reason to worry about accidentally hitting the talk button I guess. Probably nothing happening unless you spam the frequency for weeks I'd guess.
Someone complained, they send someone to check and triangulate, verify that the operator doesn't have the license, then issue a warning or fine.
I wonder how close they can triangulate? I'd guess they are SOL if I am in an apartment building with 200 other units.
I mean, if you're deliberately being a dick about it, they will ask for a warrant and have the LEO accompanying them while triangulating, they can easily figure out which unit and even room you're in by walking around in the building with directional receiver.
But in general, yeah, unless you do it regularly, living near sensitive facilities (airport, military base, hospital, factories, research labs etc) or deliberately transmitting at/near emergency frequencies (police, paramedic etc) at most you'll get yelled by a pissed off operator (at that point, stop, they could be already coordinating with someone else to triangulate you)
1w is usually okay and using 8w from a phone is probably way too much power demand
I loved it, amazing work, thanks for sharing it!
This doesn't turn your phone into a ham transceiver at all. It turns your phone into a transceiver controller. Given that a cell phone is a transceiver, this headline is rather disappointing clickbait.
Agree.
We need a compact short wave transceiver device actually.
Baofeng is 20 dollars? How much cheaper and compact do you need?
And I know, I know, Baofengs are notorious for going over the allowed noise limits… but still…
A compact CB transceiver would be fun.
Fun, but short range. A quarter wave CB antenna is about 2.7 meters long. Without that, you're making more heat than radio.
I don't see it as clickbait since the realities of the Android ecosystem is a shared context.
Most people know that just about every Android phone has a restricted hardware design, not an expandable one.
So, "turn your phone into X" is bound to automatically evoke images of another device that plugs into the phone via common connectors like USB or the audio jack and an app on the phone to control that device. That's what the phrase means to most people in the context of Android.
"Turn your phone into a ham radio transceiver controller" is neither needed nor entirely accurate, because then people will assume it can control _any_ ham radio transceiver.
The article is chiefly about a radio circuit you can "build", plus some controller software that happens to run on an Android phone. Meanwhile the headline is 100% focused on describing something that your phone can be made to do (which you have admitted that it can't).
The two don't add up, and your apologetic analysis doesn't convince me otherwise. It's still clickbait. An Android cell phone has radio guts, and that headline is just gutless.
"Turn your phone into a nuclear reactor (by plugging it into a wall outlet served by a nuclear power plant)"
Why do some people get so hung up about minor things in life. The OP has done a fantastic job, not just building it, but both the delivery and mechanics.
I agree, it is a fantastic job!
The title is still misleading to me. Not terribly so – hence my not quite serious reply – but I was expecting something like https://timestation.pages.dev/, which actually transmits using included hardware only.