Quansheng UV-K5

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Ron Parks

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Apr 30, 2024, 1:01:08 PM4/30/24
to AZTHunt
Out at Saturday's T-Hunt there were several of the Quansheng UV-K5 radios that have now turned up on Amazon and other sources for the whopping price of about $30. The real enticement of this small handheld is its firmware can be easily completely replaced so the radio's personality can be modified. The open source community has risen to this task and there is a complete firmware replacement on line that requires nothing more than a Baofeng cable to load up. I ordered one of these radios several weeks ago, immediately replaced the firmware, and have been tinkering with it. I put together a reference PDF for it based on several different pages on the github website and will provide a link below to download it.

When I went to order mine the UV-K5 version was out of stock and they were selling the "UV-K6 UV-K5(8)" version. Looks about the same, a few differences, and takes the same firmware and supposedly has better audio. I have ordered a second one to tinker with as well as it was just about as cheap as ordering a second battery haha! 

The most interesting function that the firmware adds is a "Spectrum Analyzer" mode that is more accurately a "Spectrum Sweeper." This lets you view the channel spectrum above and below your current frequency similar to other radios however, it has a "Detail Monitor Screen" mode that presents a much more granular signal strength meter than most any portable I have seen. This looks to be a real plus for t-hunting. 

I also like that the transmitter can be disabled. I immediately did this to prevent accidently hitting the PTT and burning out attenuators, TDOA, and other devices I might attach to the radio. I really only care about receiving on this radio anyway. 

Speaking of transmitting, it can be enabled to transmit outside the ham bands. Very bad idea. Aside from being illegal and a radio not type accepted by the FCC, spectrum analysis shows the transmitter is extremely dirty out of band. It will put out milliwatts (sometimes microwatts) on the intended frequency while blasting watts out on harmonics all over the spectrum. Not all that uncommon for ham radios "unlocked" for out of band transmit (or Baofengs), the transmitters were never designed for this and can go non-linear real fast. 

This radio will receive AM and SSB in addition to FM. I have not tried anything on SSB yet (you can set the tuning steps down to 1 Hz) but AM on the aircraft bands is excellent. I live adjacent to the SE practice area used by private pilots and like to listen to them and this little radio works very well. From what I can tell experimenting the radio covers from 18 MHz to about 1 GHz receive but I am guessing sensitivity is not all that great across that range.

Anyway, it will be interesting to see what the open source community comes up with for these. They have already done a fantastic job with the "egzumer" firmware and I believe there are some things here that might apply well to t-hunting as well as other things. The radio also will program channels and functions using CHIRP and it does not disturb the new firmware.

Here is a link to my PDF reference. Mostly I pulled things from the github web pages (links included) because I was lazy and didn't want to have to keep jumping around. The table at the top of the first page is how I set my side keys and such up, that is customizable so you can do something different if you want. If you look through the menus that are listed you get an idea of the scope of the many functions this firmware has. I don't claim to be an expert but I will be glad to help anyone who has one of these. 

You can download the PDF here:


73!
Ron
WB5DYG



Gordon Young

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May 3, 2024, 11:09:49 AM5/3/24
to Ron Parks, AZTHunt
The receive capability of this little radio with modified firmware and appropriate antennas, LNB's etc is a lot of fun.

I've discovered that Transmit (with a dummy load of course)
is limited to roughly the 2 meter & 70 cm bands as a limitation of the amplifier & band-pass filters: as you would expect.
In all it's fun to load the hacked firmware and try to hear stuff all the way down on 10 & 12 meters :-)

Happy hacking!
~G

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Ron Parks

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May 4, 2024, 1:27:39 PM5/4/24
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This week I took some more time with this radio and discovered some more interesting things, especially with the Detail Monitor Screen which could be described as the Expanded Signal Strength Meter. One thing that was a bit frustrating was going into the Spectrum Sweep mode did not land exactly on the VFO or memory frequency in use (since it is sweeping). This results in the Detail Monitor Screen not being exactly on frequency either when pressing PTT to enter it. I discovered that the same button that sets the starting point of the sweep in the sweep mode will allow direct entry of the frequency on the Detail Monitor Screen. Once there, press 5, enter any frequency, and you are all set. From that screen several of the same controls still work as well such as changing modulation types, bandwidth, and squelch level. The really nice function though is you can adjust the top end of the scale for the meter, which makes it more or less sensitive, making it work somewhat like a variable attenuator. This looks to be a great feature for t-hunting.

I have updated my reference document, it is available here:


Two other things I have noticed. The radio will live decode DTMF and display it on the screen. It also seems to think the tones from our t-hunt transmitters need to be decoded (secret messages???) and displays random numbers. This can be turned off at menu #55. One other thing I recommend is to go into the hidden menu #67, measure the battery voltage on the back of the radio and set the calibration value. I found this makes a big difference in the accuracy of the battery meter. If you plan on using attenuators or other accessories it is not a bad idea to disable transmit in the hidden menu as well so you don't inadvertently hit the PTT and take something out. 

All in all a very interesting little radio when updated with the egzumer firmware. I have updated two of them now with no issues at all. If anyone discovers anything else let me know, no telling what else is under the hood on these things.

73
Ron
WB5DYG

Gordon Young

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Jul 2, 2024, 11:43:05 AM7/2/24
to Ron Parks, AZTHunt
It's been a few months since this post however: There's an interesting HF receive modification for this little radio:

by adding an si4732 https://www.skyworksinc.com/-/media/Skyworks/SL/documents/public/data-shorts/Si4732-A10-short.pdf
new audio amplifier, better filtering & firmware upgrade:

All in this little flex PCB
https://www.youtube.com/watch?v=ARlpLA-wjpQ

You can reliably listen to HF

Cheers!
~Gordon
WA8Q

On Tue, Apr 30, 2024 at 10:01 AM Ron Parks <wb5...@gmail.com> wrote:
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